Novel Vegetable Protein Fractionization Process And Compositions

Abstract

According to the invention a novel vegetable protein fractionation procedure is disclosed which includes a straightforward process to obtain 7S-rich (β-conglycinin-rich) and 11S-rich (glycinin-rich) isolated protein fractions with unique functional and nutritional properties desired by the food industry. The process is much simplified compared to the art and avoids multiple steps in the usual fractionation of soy protein and uses very small amounts of salts avoiding the necessity of excessive washing and desalting steps. The process yields high amounts of protein fractions with high isoflavone contents and improved functional properties.

Description

FIELD OF THE INVENTION

The present invention relates to the field of protein extraction and purification from vegetable sources, particularly soybean.

BACKGROUND OF THE INVENTION

World soybean production has grown 400% over the last 30 years. Consumer acceptance of soybean protein products has been growing and the perception of soybean products as a healthy food is strong. The number of new soy-protein-based products in the food marketplace has increased 11.2% per year for the past 3 years. The market has become more specific and the challenge is to produce new soy-protein-based food ingredients to enhance consumer acceptance and health.

Soybeans provide a good source of low-cost protein and have become an important world commodity because they are ubiquitous, have unique chemical composition, good nutritional value, versatile uses, and functional health benefits. Yet, less than about 5% of the soybean protein available is used for food, but this percentage is likely to grow. One of the main bodies of research in recent years has focused on studying individual storage proteins (glycinin and β-conglycinin) and relating them to industrially important functional properties and functional health benefits. In spite of this extensive research these individual proteins or enriched fractions thereof are not widely available at competitive costs.

Recently, there has been increased interest in obtaining purified β-conglycinin fractions, mainly to study its health beneficial properties such as cholesterol lowering and prevention of certain types of cancer. β-Conglycinin is a trimeric protein with a molecular weight of about 180 kDa. It is composed of three subunits: a′ (˜71 kDa), a (˜67 kDa), and β (˜50 kDa).

Geneticists have been trying, with mixed success, to develop soybean lines high in glycinin and others high in β-conglycinin. Soy protein isolates have >90% of protein on dry weight basis (N×6.25). Commercial yields of soy protein isolate are approximately 33% of the starting solids in defatted white flakes, corresponding to approximately 60% of the total protein recovered in the soy protein isolate (Sathe, 1989). In general, defatted soybean flour is extracted with water under alkaline conditions and then the extract is acidified to a pH between 4 and 5 to precipitate much of the protein. The precipitate collected is the isolated soy protein. This curd can be spray-dried or neutralized and spray-dried. Some soy protein isolate processes may use a combination of salts (Saio, 1975), reducing agents (Hirotsuka et al., 1988), electro-acidification (Bazinet et al., 2000), membrane filtration (Lawton et al., 1979), high-temperature short-time thermal treatments, but the details of these commercial processes are usually not fully disclosed and vary among manufacturers.

Soy proteins are not a homogeneous group. Soy proteins have been traditionally classified by their sedimentation coefficients as analyzed by ultracentrifugation into four large groups 2S (largely albumins and enzymes), 7S (largely β-conglycinin), 11S (largely glycinin), and 15S (largely dimers of glycinin) with peak molecular weights of approximately 25,000, 160,000, 350,000, and 600,000 respectively. A typical commercial process would yield approximately 22% 2S, 37% 7S, 31% 11S, and 11% 15S proteins as extracted by water, but these amounts may vary significantly depending on variety, crop year, handling and previous thermal treatment.

There have been complex laboratory procedures developed to fractionate these proteins from each other. Such techniques cannot be practically applied for commercial scale production. Some of these techniques are also difficult to reproduce because small variations in the procedures significantly alter the final composition of the fractions. There are also several patents filed for different fractionation processes, none of them are of practical use (Howard et al., 1981; Lehnhardt et al., 1983; Masahiko et al., 1994; Samoto et al., 1996; Savolainen, 1999; and Kohno et al., 2001).

Among the known methods developed for fractionating soybean proteins, one of the first attempts is a method using low temperatures (Wolf, 1956). Wolf recovered a fairly pure 11S fraction and used the name of cold-insoluble fraction (CIF) to define it. This method is further reported as cryoprecipitation and some authors name glycinin as the cryoprotein from soybeans (Wolf and Sly, 1967). These approaches are focused on the recovery of the 11S fraction and most of them do not discuss the 7S protein fraction.

Probably the most widely utilized procedure for fractionating glycinin and β-conglycinin is the one described by Than and Shibasaki in 1976. The fractionation of 7S and 11S globulins of soybean protein was achieved by extracting soybean meal with a Tris-buffer solution containing beta-mercaptoethanol at pH 7.8, centrifuging to remove the insoluble materials (primarily fiber), adjusting the pH of the supernatant to 6.6, dialysing, centrifuging to fractionate into crude 11S-rich precipitate and 7S-rich extract, adusting the pH to the isoelectric point (˜4.6) to precipitate the 7S-rich fraction, washing, and freeze-drying. To complete this purification of each fraction several column chromatography steps are required, which make this procedure far too expensive for industrial application.

The Japanese Patent Laid Open Publication No. 55010224 discloses a method utilizing the difference in reactivity with calcium wherein a small amount of calcium salt is added during extraction, allowing a 7S-rich fraction to be extracted. A similar method was reported by Saio et al. (1973, 1974, and 1975), where the calcium salt is added as the extraction buffer and the flour is first extracted to obtain a 7S-rich supernatant and the precipitate is redisolved and centrifuged to obtain a 11S-rich fraction. These methods have several drawbacks that make them impractical for industrial application. Beyond the processing drawbacks, the purities reported on an ultra-centrifugal basis (a less accurate method than we employ) are about 60%, which are lower than the purities obtained by our invention.

Further, other experimental methods to fractionate soy proteins have been reported by Roberts et al., 1965; Eldrige et al., 1967; Nagano et al., 1992; and Thiering et al., 2001. These methods for fractionating soy proteins are too expensive for industrial purposes, especially for the industrial production of soy protein isolates, and in some cases utilize chemicals that are not food-grade.

Recently, another method was developed by Saito et al. (2001), where the soy protein extract is treated with the enzyme phytase in order to hydrolyze phytic acid. They claim that by means of adjusting the pH, two fractions are obtained. The first fraction is rich in glycinin and the second rich in β-conglycinin. They claim that they obtain purities of about 80% for both fractions. The method requires incubation times and temperatures that make it impractical for industrial purposes and difficult to reproduce (Aldin, 2004). because of long process times and potential for microbiological growth and activity. Another drawback is that, it uses enzymes that add to the cost of the process.

Some attempts have been made to scale up some of these processes from the laboratory and to adapt them to pilot-plant production. Wu et al. (1999) successfully scaled up a method developed by Nagano et al. (1992) to obtain kg quantities of the individual soy storage proteins. But, the fraction yields are very low and the procedure is extremely costly and complicated for industrial production. Later, this procedure was improved (Rickert et al., 2003) obtaining three protein fractions, one β-conglycinin-rich, one glycinin-rich, and an intermediate mixture of the former two proteins plus a significant amount of lipoxygenase. Two waste stream products were produced, the spent flakes and the whey. This process was successfully scaled up to pilot-plant production, but its commercial application is questionable since it requires several extraction, centrifugation, and desalting steps.

It is therefore a primary objective of the present invention to provide a method of producing two separate vegetable protein isolates and/or products—one enriched for β-conglycinin and another enriched for glycinin.

It is another objective of the present invention to provide a method which avoids multistage fractionations steps and uses very small amounts of salts avoiding excessive washing and desalting steps.

It is still another objective to provide soy protein products that are highly functional in their performance as ingredients and, when possible, deliver high contents of naturally occurring healthy phytochemicals.

These and other objectives will become apparent from the following description.

SUMMARY OF THE INVENTION

The present invention provides a straightforward and commercially useful procedure to fractionate soy proteins to obtain β-conglycinin-rich and glycinin-rich isolated protein fractions with unique functional and nutritional applicability in the food industry. The present invention avoids multistage fractionation steps and uses very small amounts a f salts avoiding the necessity of excessive washing and desalting steps, it also avoids managing large volumes of liquid since the invention utilizes a single extraction step and does not need dilution steps, which are common operations in previous attempts of the art. The protein isolates and products of the invention are highly soluble and dispersible, usually higher in isoflavone content, are better emulsifiers and foaming agents than are traditional soy protein products, and have unique viscosity control properties.

The present invention is a simple method to produce fractionated vegetable proteins, which comprises extracting the proteins from the vegetable source, such as soybeans (defatted white flakes with high protein dispersibility index preferred), soybean flour that is partially de-fatted or even with full fat may also be used according to the invention. Generally, proteins are extracted with a dilute alkali at pH values between 7.0 and 11.0, at temperatures between 4° C. and 80° C.; obtaining a protein extract that is a mixture of different proteins naturally present in the soybean source; and subsequently subjecting the resulting extract to a fractional precipitation by adding small amounts of one or more multivalent cationic salt, such as calcium, magnesium or zinc, or by adding one or more multivalent anions, such as ethylene diamine tetraacetic acid (EDTA), and a food-grade reducing agent, such us sodium bisulfite, sodium sulfite, or other reducing agent; adjusting the pH of the slurry to between 7.0 and 5.0 and the temperature to between 2° C. and 35° C. in order to obtain a precipitate that is mainly comprised of glycinin, and a supernatant that is enriched in β-conglycinin. The resulting supernatant can be adjusted to a pH between 6.0 and 3.0 in order to obtain a β-conglycinin-rich precipitate and a supernatant that will be rich in lipoxygenase and trypsin inhibitors. The protein precipitates can be dried by any conventional method with or without previous neutralization with dilute alkali. These precipitates are single-protein-enriched isolates and/or products with unique compositions and superior functional properties that enhance the performance of the protein in food or industrial systems. The products obtained by this invention are usually enriched in naturally occurring isoflavones and have significant process cost advantages over alternative soy protein fractionation processes.

The combination of a multivalent salt and a reducing agent in combination with pH adjustment, with or without temperature reduction, in order to precipitate two protein fractions is a unique approach. The combination of these factors is new to the art. The resulting protein fractions can be used for a number of different processes and products, which are further detailed herein.

DETAILED DESCRIPTION OF THE FIGURES

FIG. 1 is a flow chart showing the method of the invention.

FIG. 2 is a flow chart showing the steps of a control procedure (Modified Nagano).

FIG. 3 is a flow chart showing the steps of traditional soybean protein isolate manufacture.

FIG. 4 is a diagram showing the biosynthetic pathway of oligosaccharide synthesis in soybeans. Adapted from Wilson (2001). UGE denotes UDP-glucose-4′-epimerase; GS, galactinol synthase; RS, raffinose synthase; SS, stachyose synthase; and MI-1PS, myo-inositol phosphate synthase.

FIG. 5 is a flowchart showing the initial steps of the invention.

FIG. 6 is a flowchart showing the modification where the reducing agent is added during the initial protein extraction.

FIG. 7 is a flowchart depicting modifications including membrane filtration.

FIG. 8 is a flow chart depicting modifications including hydrolyzing, jet-cooking homogenizing and drying.

FIG. 9 is a flow chart showing the production of an isoelectric soy protein isolate.

FIG. 10 is a flow chart showing the membrane-filtered soy protein hydrolyzate.

FIG. 11 is a flow chart showing the preparation of high-sucrose soy products.

FIG. 12 is a flow chart showing the preparation of products from partially de-fatted or fall-fat soy flour.

FIG. 13 is a flow chart showing the invention using defatted soy flour where both the reducing agent and calcium salt are added to the extraction step in order to produce a glycinin-rich flour and a β-conglycinin-rich extract.

FIG. 14 is a flow chart showing the invention using partially defatted or full-fat soy flour.

FIG. 15 is a flow chart showing the process when the starting material is soy flour.

FIG. 16 shows the products of the invention further modified to produce soymilk products.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The process of the invention gives an alternative to genetic modification to produce soy protein isolates high in either glycinin or high in f-conglycinin from traditional soybean lines. This is of particular interest for exports of these products to Europe and Japan, where there is resistance to consuming genetically modified products. The process of the invention obtains two high value products by using a single protein fractionation step. This is a significant benefit compared to previous approaches. One of the problems associated with protein fractionation is that there are usually large losses of protein to less valuable fractions. Phytochemical recovery (specifically but not limited to isoflavones) is significantly higher in this invention, since the process does not require desalting steps nor excessive washing, which are two critical points of phytochemical loss in previous approaches. Additionally, the salts used in our process are healthier than the traditionally used ones. An added benefit of this invention is that it produces highly functional food ingredients that make them appealing for industrial applications.

The invention is superior to the previously known procedures to the art, since it utilizes all food-grade chemicals, fewer operating steps, achieves higher yields of fractionated protein products, is more cost effective since the process utilizes less water and washing steps, and the products have superior functional properties and higher isoflavone contents. Over all, our invention is less expensive, less complicated, and produces less waste than previously known processes.

The present invention is a simple method to produce fractionated vegetable proteins. In a preferred embodiment the vegetable source is soybeans. This can include normal or naturally occurring soybean varieties, or soybeans modified by tradtitional breeding methods and/or genetic engineering (e.g. lipoxygenase-null, low-phytate, high-oleic, high-β-conglycinin, high-glycinin, high-cysteine, low-linolenic, etc.). First the proteins are extracted from the vegetable source. The protein source is preferably defatted, but with minor modifications as described herein, partially defatted or even full-fat soy material can be used. Defatted soybean white flakes with high protein dispersibility index are most preferred. The vegetable protein source is extracted with a dilute alkali at pH values between 7.0 and 11.0, at temperatures between 4° C. and 80° C.; thereby obtaining a protein extract that is a mixture of different proteins naturally present in the vegetable source. The resulting extract is then subjected to a fractional precipitation by adding small amounts of a multi-valent cationic salt, such as calcium, magnesium, zinc, etc. This step can also be performed with a multi-valent anionic salt, such as ethylene diamine tetraacetic acid and/or any of its salts. A food-grade reducing agent, such as sodium bisulfite, sodium sulfite, ascorbic acid, erythorbic acid, L-cysteine, or other reducing agent is also added. The reducing agents can be added during the protein extraction step (before or after alkali conditions) rather than added to the protein extract. Next, the pH of the slurry is adjusted to between 7.0 and 5.0 and the temperature to between 2° C. and 35° C. in order to obtain a precipitate that is mainly comprised of the glycinin, and a supernatant that is enriched in β-conglycinin. The resulting supernatant can be adjusted to a pH between 6.0 and 3.0 in order to obtain a β-conglycinin-rich precipitate and a supernatant rich in lipoxygenase and trypsin inhibitors. The glycinin and β-conglycinin protein extracts and/or curds can be further processed in any of a number of ways depending upon the desired use. Several of such processes and uses are further detailed herein.

The precipitates can be dried by any conventional method with or without previous neutralization with dilute alkali. These precipitates are single protein enriched isolates with unique compositions and superior functional properties. The products obtained by this invention are usually enriched in isoflavones and have significant process cost advantages over alternative soy protein fractionation processes.

In a further embodiment (see FIG. 7), the β-conglycinin-rich precipitate can be redissolved by neutralizing the precipitate with dilute alkali to obtain a neutralized β-conglycinin-rich protein slurry. The neutralized slurry can then be membrane filtered and neutralized to obtain a concentrated β-conglycinin-rich protein slurry retentate and a filtrate composed mostly of water and minerals. This process can also involve steps of jet-cooking or any other thermal processing of the neutralized β-conglycinin-rich protein slurries and subsequently homogenizing and/or drying to obtain a β-conglycinin-rich soy protein isolate powder. Lecithin and/or any other food-grade functional additives may be added prior to or after the thermal processing step as desired to said β-conglycinin-rich slurries, which may be followed by homogenizing and/or drying said mixture to obtain a β-conglycinin-rich soy protein product.

In another embodiment (FIG. 8), the said β-conglycinin-rich slurry may be hydrolyzed to obtain a β-conglycinin-rich hydrolyzed slurry. The β-conglycinin-rich hydrolyzed slurry may then be supplemented with lecithin or other food-grade functional additives and thermally processed and/or homogenized and/or dried to obtain a “hydrolyzed” β-conglycinin-rich soy protein isolate powder or a “hydrolyzed” β-conglycinin-rich soy protein product, or a “hydrolyzed” β-conglycinin-rich soy protein isolate product as desired.

In yet another embodiment (FIG. 9), the β-conglycinin rich curd can be jet-cooked or otherwise thermally processed and subsequently homogenized and/or dried to obtain an “isoelectric” β-conglycinin-rich soy protein isolate powder. Lecithin and/or other food-grade additives may also be added either before or after the thermal processing the protein slurry then may be homogenized and/or dried to obtain an “isoelectric” β-conglycinin-rich soy protein product.

In yet another embodiment (FIG. 10), the β-conglycinin-rich supernatant is membrane filtered to obtain a β-conglycinin-rich retentate and a filtrate that is mainly composed of salts and sugars. The retentate may then be subsequently homogenized and/or dried to obtain a “membrane filtered” β-conglycinin-rich soy protein isolate powder. Lecithin and/or any other food-grade additive may be added either before or after jet cooking or other thermal process, which may be followed by homogenizing and/or drying to form a “membrane filtered” β-conglycinin-rich soy protein isolate product.

In yet another embodiment (FIG. 8), the β-conglycinin-rich supernatant may be hydrolyzed to obtain a β-conglycinin-rich hydrolysate extract. The pH of the extract may then be adjusted to between about 4 and about 6 to obtain a hydrolyzed β-conglycinin-rich precipitate and a supernatant that is mainly composed of minerals and sugars. The precipitate may then be re-dissolved and neutralized with dilute alkali to obtain a neutralized hydrolyzed β-conglycinin-rich slurry, which may be membrane filtered said to obtain a concentrated hydrolyzed β-conglycinin-rich slurry retentate and a filtrate that is mainly composed of water and salts. As before, the neutralized hydrolyzed β-conglycinin-rich protein slurry may be j et-cooked or otherwise thermally processed, and/or homogenized and/or dried to obtain a hydrolyzed β-conglycinin-rich soy protein isolate powder. A hydrolyzed β-conglycinin-rich soy protein isolate product may be formed by adding lecithin or any other food-grade additive either prior to or after thermal processing.

In yet another embodiment (FIG. 10), the β-conglycinin-rich hydrolysate extract may be membrane filtered to obtain a hydrolyzed β-conglycinin-rich retentate and a filtrate that is mainly composed of minerals and sugars. The retenate may then be jet cooked or otherwise thermally processed, and/or homogenized and/or dried to obtain a hydrolyzed β-conglycinin-rich soy protein isolate powder. Lecithin or other additives may be added prior to or subsequent to the thermal processing to form a hydrolyzed β-conglycinin-rich soy protein product.

In yet another embodiment (FIG. 7), the glycinin-rich precipitate may be re-dissolved by neutralizing with dilute alkali to obtain a neutralized glycinin-rich slurry. The slurry may then be membrane filtered to obtain a concentrated glycinin-rich slurry retentate and a filtrate that is mainly composed of water and minerals. The neutralized glycinin-rich protein slurries may then be jet cooked or otherwise thermal processed, and/or homogenized and/or dried to obtain a glycinin-rich soy protein isolate powder. Lecithin or other food-grade additives may be added just before or after thermal processing to produce a glycinin-rich soy protein product.

In still another embodiment (FIG. 8), the glycinin-rich slurry may be hydrolyzed to obtain a hydrolyzed glycinin-rich slurry. As before, the slurry may then be jet cooked, or otherwise thermally processed, and/or homogenized and/or dried to obtain a “hydrolyzed” glycinin-rich soy protein isolate powder. To obtain a “hydrolyzed” glycinin-rich soy protein product, lecithin or other food-grade additives may be added just before or after thermal processing.

In yet another embodiment (FIG. 9), the glycinin-rich precipitate slurry may be jet-cooked or otherwise thermally processed and/or subsequently homogenized and/or dried to obtain an “isoelectric” glycinin-rich soy protein isolate powder. Lecithin and other food-grade additives may be added prior to or after thermal processing to form an “isoelectric” glycinin-rich soy protein product.

In yet a further embodiment, the soybean source may be High-sucrose/Low-stachyose soybeans (FIG. 11) and the method includes further steps of jet cooking or any other thermal processing said enriched β-conglycinin extract and/or subsequently, homogenizing, and/or drying said extract to obtain a β-conglycinin-rich high-sucrose protein product. Lecithin and other food additives may be added prior to or subsequent to the thermal processing to from a β-conglycinin-rich high-sucrose protein product.

In still another embodiment, the defatted vegetable source is obtained through organic solvent or supercritical CO₂ extraction of the fat from the soybean matrix (FIG. 10). The defatted vegetable source may also be obtained through screw pressing and/or Gas-Supported Screw Pressing (GSSP) and/or other mechanical oil extraction method, such as the Extruding-expelling Process, that produces a partially defatted soybean source. In this embodiment the partially defatted soybean source is subsequently extracted with a dilute alkali of approximately pH 7 to approximately pH 11 to form a mixture of proteins present in said vegetable source, and then centrifuged to obtain a supernatant oil-rich “cream” fraction and a supernatant protein extract from said mixture, then the protein extract is subjected to fractional precipitation and reducing agents as described previously. The resulting product may then be jet cooked or otherwise thermally processed and/or thereafter homogenized and/or dried to obtain a dried high-oil/high-protein product.

In yet another embodiment (FIG. 13), the method for obtaining a β-conglycinin-rich isolated protein fraction and/or a glycinin-rich fiber-rich flour/concentrate fraction from a soybean source comprises, obtaining a defatted soybean source; extracting said source with dilute alkali or acid of pH of about approximately 6 to approximately 10 to form a mixture of proteins present in said vegetable source; subjecting said mixture to fractional precipitation with a multi-valent salt and a reducing agent to form a slurry; adjusting said slurry to a pH of approximately 7 to approximately 5 to obtain a precipitate, which is enriched in glycinin and fiber, and a supernatant, which is enriched in β-conglycinin as compared to percentage protein in the original mixture. The extract may be treated as described earlier to form protein isolates and products. Multi-valent cationic salts useful in the foregoing can include but is not limited to calcium, magnesium or zinc, and their mixtures, or in as alternative, the multi-valent anion EDTA and/or any of its salts may be used. Reducing agents may include but is not limited to sodium bisulfite, sodium sulfite, ascorbic acid, erythorbic acid, L-cysteine or other food-grade reducing agents. Soybean sources can include normal or naturally occurring soybean varieties, genetically modified soybeans such as High-sucrose/Low-stachyose soybeans, which are processed as described earlier. The vegetable source may also be obtained through hexane extraction of the fat from the vegetable matrix or through supercritical CO₂ extraction or through screw pressing and/or Gas-Supported Screw Pressing (GSSP) and/or other mechanical oil extraction method, such as Extruding-expelling, that produces a partially defatted soybean source and is processed as described earlier. As shown in FIG. 14, partially defatted car full-fat soy flour may also be used according to the invention.

When the partially defatted soybean source is replaced by a full-fat soybean source comprising the processing steps therein described and obtained, the product and processes thereafter described have products that differ in that the products obtained will have higher oil content, a protein content of less than 90%, and a higher yield of oil-rich cream fraction. See FIGS. 14 and 15.

In yet another embodiment (FIG. 16), additional steps of deodorizing and/or packaging and/or sterilizing and/or packaging are shown to obtain a β-conglycinin-rich defatted soymilk, which may be dried to form powder or which may have lecithin or other food-grade additives added as described herein and shown in FIGS. 15 and 16.

In yet another embodiment, the β-conglycinin-rich extract/supernatant may be subjected to chemical modification, such as but not restricted to acylation, phosphorylation, and deamidation, to obtain a chemically modified β-conglycinin-rich extract. The extract may also be enzymatically modified by phytase and/or glycosidase, or any other enzyme to obtain an enzymatically modified β-conglycinin-rich extract.

The redissolving step and/or dispersing said glycinin-rich precipitate may also be subjected to chemical an enzymatic modification such as but not restricted to acylation, phosphorylation, and deamidation, to obtain a chemically modified glycinin-rich slurry. enzymatic modification such as but not restricted to phytase, and/or glycosidase and/or pectinase and/or cellulase to obtain an enzymatically modified glycinin-rich slurry which is then processed as described.

Since soybeans is an inexpensive commodity, methods to process it cannot be too sophisticated in order to preserve economical feasibility. Our invention addresses the following problems and solves them adequately:

• • (1) The starting extracts are obtained by using similar technologies to any other aqueous-alkali extraction; the process does not need new equipment.
  • (2) The chemicals utilized are food-grade to allow the use of the products in the food industry; the process not only uses food-grade chemicals, but also may employ calcium, a “healthy” salt.
  • (3) The method does not use excessive amounts of water (for dilutions or extractions) to increase the efficiency of the production; and is successful with single-stage extraction of protein and uses no dilution or desalting steps. This is a significant advantage compared to previous method, and the process is thus more environmentally friendly.
  • (4) The use of low temperatures should be avoided to reduce costs; the process of the invention has proven to be efficient without holding protein slurries at low temperatures, which almost all of the previous fractionation procedures require. This significantly reduces processing costs and speeds up production.
  • (5) The yields and purities of the fractions should be manageable to obtain consistency and uniformity of production; the invention achieves this goal, since it is a simple process, which in turn facilitates control and makes it reproducible. These two factors (production control and reproducibility) are of great importance when producing soy protein fractions on industrial scale.
  • (6) The invention allows us to produce different compositions of β-conglycinin and glycinin globulin proteins in arbitrary proportions giving a range of unique soy protein isolates and/or products, each with unique compositions and functionalities, by adjusting the multi-valent ion concentration and the pHs used to precipitate the fractions. None of the processes previously described in the art are able to do this.
  • (7) The process must be a simple straightforward procedure, avoiding multi-stage separations and precipitations. The invention is the simplest of all fractionation procedures known to the art.
  • (8) The process of the invention not only fractionates the β-conglycinin and glycinin globulins effectively, but also renders healthy products with broad applicability and superior functional properties compared to products previously known to the art. While the methods disclosed herein specifically reference soybean, the invention is not so limited, it will be understood by those of skill in the art that any vegetable source can be used according to the invention to isolate and purify proteins therefrom with no more that routine experimentation according to the teachings herein.

EXAMPLE 1

The process of the invention was carried out in duplicate. Means of solids yields, protein yields and purity data are reported in Tables 1, 2 and 3, respectively.

All processes started from the same material, defatted soybean flour from IA 2020 variety, 1999 harvest, and defatted in our pilot plant in January 2000. The meal had a PDI of 93.8. The following flow charts are provided: the method of the invention (FIG. 1), control procedure (Modified Nagano, FIG. 2), and traditional soybean protein isolate procedure (FIG. 3).

All processes had the same starting step, the meal was extracted with de-ionized water at flour-to-water ratio of 1:15; the pH was adjusted to 8.5. The resulting slurry was stirred at 25° C., and after 1 hour the slurry was centrifuged at 14,000×g and 25° C. for 30 minutes to separate the spent flour (largely fiber) from the protein extract. The resulting protein extract, comprising 78.6% of the protein originally present in the flour, was divided in twelve aliquots.

To each of these aliquots a combination of CaCl₂ and NaHSO₃ was added at different concentrations, the pH was adjusted to 6.4, and stirred for 15 minutes. After this initial stirring, all samples were placed in a cold room at 4° C. overnight. The next day the extracts were stirred again and centrifuged at 14,000×g and 4° C. for 30 minutes, obtaining a glycinin-rich precipitate and a β-conglycinin-rich supernatant. The supernatant was adjusted to pH 4.8 and centrifuged again under the same conditions, recovering a β-conglycinin-rich curd, and an extract that is normally termed whey by those skilled in the art.

Additionally, two of these aliquots, in duplicate, were processed according to methods reported in the literature as a control, and an additional control was performed by not adding any chemicals to the extract (identified as Treatment #2 in the tables).

Treatments were as follows:

• • Treatment #1 control modified Nagano method, previous method (FIG. 2)
  • Treatment #2 control fractionation for only pH adjustment.
  • Treatment #3 fractionation with addition of 5 mM of SO₂ and 5 mM of Ca²⁺ (FIG. 1, invention)
  • Treatment #4 fractionation with addition of 5 mM of SO₂ and 10 mM of Ca²⁺. (FIG. 1, invention)
  • Treatment #5 fractionation with addition of 10 mM of SO₂ and 5 mM of Ca²⁺. (FIG. 1, invention)
  • Treatment #6 fractionation with addition of 10 mM of SO₂ and 10 mM of Ca²⁺. (FIG. 1, invention)

Solids and Protein Mass Balances were Performed and Purities were Assessed by urea-SDS-PAGE gel electrophoresis. Significant differences between different treatments were revealed by using paired t-tests at α=0.05.

TABLE 1
Solids yield for each fraction and treatment
	Glycinin	β-conglycinin
Treatment	(%)	(%)
Treatment #1 (prior method)	12.96 a, b	10.06 a
Treatment #2 (control with no chemicals)	11.29 a	26.56 d
Treatment #3 (new)	16.05 c	22.32 c
Treatment #4 (new)	18.22 d	19.40 b
Treatment #5 (new)	14.13 b	23.70 c
Treatment #6 (new)	17.76 d	18.86 b
N = 2. Means in the same column followed by different letters are statistically different at α = 0.05.

From the data shown in Table 1, it can be seen that the new processes give significantly higher solids yields in the products obtained compared to the prior method. These yields are in some cases more than 100% better for the β-conglycinin fraction; this is the fraction that current research and industry attention are focused on because of its potential health beneficial properties.

TABLE 2
Protein yield for each fraction and treatment
	Glycinin-rich	β-conglycinin-rich
	Fraction	Fraction
Treatment	(%)	(%)
Treatment #1 (prior method)	24.76 a	18.51 a
Treatment #2 (control, with no	21.23 a	48.38 b
chemicals)
Treatment #3 (new)	27.97 a, c	40.16 c
Treatment #4 (new)	31.46 c	35.45 d
Treatment #5 (new)	25.81 a	41.48 c
Treatment #6 (new)	32.44 c	34.46 d
Means in the same column followed by different letters are statistically different at α = 0.05.

From the data shown in Table 2, it can be seen that the new processes have significantly higher protein yields in the products compared to the prior method. These yields are in some cases more than 100% better for the β-conglycinin fraction than achieved by methods previously known to those skilled in the art.

TABLE 3
Fraction purity for each fraction and treatment
		Lipoxygenase	β-Conglycinin	Glycinin	Others
Product	Treatment	(%)	(%)	(%)	(%)
Protein Extract		4.52	41.36	50.70	3.42
Glycinin-rich	Trt. #1 (prior method)	6.96 a	14.19 d	72.38 b	6.47 b
fraction	Trt. #2	3.33 c	28.62 a	62.72 d	5.32 c
	Trt. #3 (new)	0.00 d	25.09 b	74.91 a	0.00 e
	Trt. #4 (new)	4.27 b	29.48 a	57.65 e	8.60 a
	Trt. #5 (new)	0.00 d	20.36 c	75.20 a	4.45 d
	Trt. #6 (new)	4.31 b	28.33 a	67.35 c	0.00 e
β-Conglycinin	Trt. #1 (prior method)	5.07 c	81.26 a	13.67 d	0.00
rich fraction	Trt. #2	7.01 a	64.76 d	27.76 a	0.00
	Trt. #3 (new)	5.25 c	76.95 b	17.81 b, c	0.00
	Trt. #4 (new)	5.84 b, c	78.94 a	15.22 c, d	0.00
	Trt. #5 (new)	5.13 c	74.65 c	20.22 b	0.00
	Trt. #6 (new)	6.35 b	78.38 a, b	15.27 c, d	0.00
N = 2. Means in the same column, for a given fraction, followed by different letters are statistically different at α = 0.05.

From the data provided in Table 3, it can be seen that the new processes have similar or better purities to the ones obtained by Treatment #1 (prior method).

Treatment #3 was selected for scale up at a lab level in order to produce enough samples for further characterizing these new products.

The procedures were as follows: 100 g of defatted soybean meal (IA 2020 variety, 1999 harvest, defatted in our pilot plant in January 2000) was treated according to the conditions explained for Treatment #3 (FIG. 1), in addition to this, Treatment #3 was repeated without the chilling step, and from the same flour we produced two controls, a traditional isolated soy protein (FIG. 3), and the modified Nagano procedure (FIG. 2).

Once the products were obtained, they were dried and stored in sealed containers until analyzed. All procedures were replicated in duplicate. Solids and ash contents were determined according to standard methods. Protein was determined by using the Dumas method. Protein composition was measured by using urea-SDS-PAGE according to a method reported by Wu et al. (1999). Isoflavones were analyzed according to the method described by Murphy et al. (1999). Thermal behaviors of these samples were determined by using differential scanning calorimetry (DSC) (Rickert et al., 2004). Solubility was measured according to Dias et al. (2003). Surface hydrophobicity was measured according to methods described by Wu et al. (1999). Emulsification properties were determined according methods described by Rickert et al. 2004. Foaming properties were determined according methods described by Bian et al. (2003). Rheological behavior was determined by using a cone and plate viscometer (Rickert et al., 2004). All measurements were made at least in triplicate.

Statistical analysis was performed with SAS program, LS means, GLM, Analysis of variance and least significant differences (LSD) were determined to analyze the data.

Yields were determined as follows:

Yield %=(mass of a component in the given fraction/total mass of the same component in the initial material)*100. All yields were calculated on a dry weight basis.

TABLE 4
Yields of solids, protein and isoflavones for traditional isolate, modified
Nagano's procedure, and the new process
			Yield	Yield of
		Yield of Solids	of Protein	Isoflavones
Process	Product	(%)	(%)	(%)
Traditional	Isolate	40.70 a	69.71 a	54.41 a
Nagano's	Glycinin	11.60 e	24.76 f	9.60 f
	Intermediate	18.16 c	26.76 e	20.91 d
	β-Conglycinin	11.51 e	18.51 g	3.28 g
New 4C	Glycinin	15.51 d	24.41 f	20.55 d
	β-Conglycinin	23.10 b	37.16 b	37.50 b
New RT	Glycinin	15.70 d	29.92 d	15.86 e
	β-Conglycinin	23.34 b	32.41 c	34.83 c
LSD		2.18	1.92	2.59
LSD = least significant difference, means followed by different letters in the same column are statistically different. N = 2.
Nagano's = Treatment # 1 (prior method)
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 4, we concluded that our invention yield a similar amount of solids to the traditional isolated soy protein. The new process yielded significantly higher amounts of solids when comparing the sum of yields of the glycinin and β-conglycinin-rich fractions against the similar sum of the control procedure. The control procedure, previous method, yielded a significant amount of solids in the so called “intermediate” fraction. Our process does not produce this lower quality fraction. The new process consistently yielded 62% of the protein originally present in the meal in the valuable fractions, whereas the control procedure only yielded 43%. The yields of isoflavones in our products were also significantly superior to the yields produced by the control procedure. The β-conglycinin-rich fraction yielded ten times more isoflavones using our invention, compared to the prior method; and our glycinin fraction yielded between 1.5 and 2 times more isoflavones compared to the control. Our invention has proven to yield more solids, more protein and more isoflavones compared to the control fractionation procedure (prior method).

TABLE 5
Protein, total isoflavone and ash contents of traditional soy protein isolate,
modified Nagano's procedure, and our new processes
		Protein	Total Isoflavones	Ash
Process	Product	(%)	(μg/g)	(%)
Traditional	Isolate	91.35 c, d	2570 c	4.24 e
Nagano's	Glycinin	96.68 b	1591 g	3.89 f
	Intermediate	80.26 e	2213 e	14.27 a
	β-Conglycinin	92.19 c	548 h	10.14 b
New 4C	Glycinin	98.89 a	2547 d	3.22 g
	β-Conglycinin	90.04 d	3120 a	6.05 c
New RT	Glycinin	96.55 b	1942 f	2.99 g
	β-Conglycinin	91.19 c, d	2868 b	5.30 d
LSD		1.43	192	0.24
LSD = least significant difference, means followed by different letters in the same column are statistically different. N = 2.
Nagano's = Treatment # 1 (prior method)
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 5 it can be seen that all of our products contained at least 90% protein, the industrial standard for isolated soy protein. The total isoflavone contents were superior compared to the prior method, and the ash contents were significantly lower than the ash contents of the control procedure (prior method).

TABLE 6
Fraction purity for each fraction and treatment
		Lipoxygenase	β-Conglycinin	Glycinin	Others
Process	Product	(%)	(%)	(%)	(%)
Traditional	Isolate	3.92 c, d	35.91 d	52.73 b	7.43 a
Nagano's	Glycinin	3.58 c, d	17.31 f	74.20 a	4.90 c
	Intermediate	9.24 a	48.86 c	41.90 c	0.00 d
	β-Conglycinin	4.12 c	80.30 a	15.57 e	0.00 d
New 4C	Glycinin	0.00 e	17.91 f	76.32 a	5.77 b
	β-Conglycinin	6.82 b	82.17 a	11.01 f	0.00 d
New RT	Glycinin	0.00 e	26.85 e	73.15 a	0.00 d
	β-Conglycinin	3.53 d	75.00 b	21.47 d	0.00 d
LSD		0.58	2.41	3.52	0.79
LSD = least significant difference, different letters in the same column are statistically different. N = 2.
Nagano's = Treatment #1 (prior method).
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 6, we concluded that the products obtained by our invention had, with a much simpler process, similar purities to the control process (prior method).

TABLE 7
Temperatures and enthalpies of denaturation
		β-Conglycinin		β-Conglycinin	Glycinin	Total
		Td	Glycinin Td	Enthalpy	Enthalpy	Enthalpy
Process	Product	(° C.)	(° C.)	(mJ/mg)	(mJ/mg)	(mJ/mg)
Traditional	Isolate	73.4 b, c,	91.9 a, b	1.18 d, e	7.25 c	8.43 d
Nagano's	Glycinin	74.7 a, b	89.1 d	0.32 e	15.65 b	15.97 b
	Intermediate	74.8 a, b	93.1a	1.48 d	2.91 d	4.31 f
	β-Conglycinin	75.1 a	88.9 d	10.64 a	0.06 f	10.70 c
New 4C	Glycinin	73.3 c, b	91.0 b, c	0.61 d, e	19.23 a	19.84 a
	β-Conglycinin	75.1 a	89.8 c, d	6.47 b	0.55 e, f	7.01 e
New RT	Glycinin	72.8 c	91.3 b, c	0.81 d, e	19.33 a	20.15 a
	β-Conglycinin	74.7 a, b	90.8 b, cc	4.96 c	1.19 e	6.15 e
LSD		1.58	1.55	0.93	1.06	1.23
LSD = least significant difference, means followed by different letters in the same column are statistically different. N = 2.
Nagano's = Treatment # 1 (prior method).
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 7, it can be seen that the glycinin-rich fractions obtained by our process had a significantly higher enthalpies of denaturation, making this protein more functional.

TABLE 8
Solubility and surface hydrophobicity
			Surface
		Solubility at pH 7	Hydrophobicity
Process	Product	(%)	(dimensionless)
Traditional	Isolate	90.97 a, b	351.1 a
Nagano's	Glycinin	88.09 b, c	159.8 c
	Intermediate	39.70 f	156.2 c
	β-Conglycinin	93.79 a	177.7 c
New 4C	Glycinin	85.16 c	161.3 c
	β-Conglycinin	71.76 e	226.4 b
New RT	Glycinin	79.27 d	153.4 c
	β-Conglycinin	80.52 d	187.1 c
LSD		3.90	39.2
LSD = least significant difference, means followed by different letters in the same column are statistically different. N = 2.
Nagano's = Treatment #1 (prior method).
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 8, it can be seen that the products obtained by our invention had slightly lower solubilities, but still were highly soluble. The surface hydrophobicities of the new products were similar to those of the control.

TABLE 9
Emulsification properties
		Emulsification	Emulsification	Emulsi-
		Capacity (g of	Activity	fication
		oil emulsified/g	(absorbance	Stability
Process	Product	of product)	at 500 nm)	Index
Tradi-	Isolate	583.1 d	0.283 b	175.4 a, b
tional
Nagano's	Glycinin	350.7 e	0.152 d, e	84.3 c
	Intermediate	232.0 f	0.168 d	62.0 c
	β-Conglycinin	585.9 d	0.306 a	194.0 a
New 4C	Glycinin	876.1 a	0.140 e	73.1 c
	β-Conglycinin	678.2 b	0.276 b	192.3 a
New RT	Glycinin	683.7 b	0.149 d, e	68.8 c
	β-Conglycinin	647.0 c	0.244 c	151.5 b
LSD		30.3	0.022	32.1
LSD = least significant difference, means followed by different letters in the same column are statistically different. N = 2.
Nagano's = Treatment # 1 (prior method).
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data provided in Table 9, it can be seen that the products obtained by our invention had significantly better emulsification properties. In some cases, the improvement was 2.5 times more than those achieved by employing the prior method. This very important functional property is fundamental in food applications such as salad dressings, frozen disserts, and mayonnaise. Since the emulsification activity and stability of these new products were similar to those of the control, but had much superior emulsification capacity, we concluded that the products produced by the new process are superior to the prior method.

TABLE 10
Foaming properties
			Foaming
		Foaming	Stability	Rate of
		Capacity	(k = 1/	Foaming
Process	Product	(mL/mL)	(mL*min))	(vi = mL/min)
Traditional	Isolate	1.096 c	0.013 c, d	11.1 d
Nagano's	Glycinin	0.964 d	0.089 a	2.0 f
	Intermediate	0.958 d	0.004 d	17.2 c
	β-Conglycinin	1.069 c, d	0.018 c	12.4 d
New 4C	Glycinin	1.428 b	0.075 b	8.4 e
	β-Conglycinin	1.597 a	0.008 d	32.0 b
New RT	Glycinin	1.654 a	0.068 b	10.3 d, e
	β-Conglycinin	1.648 a	0.007 d	34.5 a
LSD		0.130	0.009	2.3
LSD = least significant difference, means in the same column followed by different letters are statistically different. N = 2.
Nagano's = Treatment #1 (prior method).
New 4C = Treatment #3 with chilling step.
New RT = Treatment #3 at room temperature.

From the data shown in Table 10, it can be seen that the new products have superior foaming capacities, superior foaming stabilities (the foaming stability as it is expressed in this table, the lower the better), and similar rates of foaming to those achieved by employing prior methods. Foaming capacities were in some cases between 50 and 60% better for our products than for the control (prior method) and the traditional soybean protein isolate.

TABLE 11
Dynamic viscosity behavior
		Consistency	Flow Behavior
Process	Product	Coefficient (k)	Index (n)
Traditional	Isolate	0.1507	0.7282
Nagano's	Glycinin	N/A	N/A
	Intermediate	N/A	N/A
	β-Conglycinin	N/A	N/A
New 4C	Glycinin	0.0110	0.8673
	β-Conglycinin	0.5211	0.5854
New RT	Glycinin	0.0103	0.9167
	β-Conglycinin	0.0700	0.7886
LSD		N/A	N/A
N=2.
Nagano's Treatment #1 (prior method).
New 4C Treatment #3 with chilling step.
New RT Treatment #3 at room temperature.

From the data provided in Table 11, it can be seen that the β-conglycinin-rich fractions were more viscous than the glycinin-rich fractions, and that the traditional isolate gave an intermediate value. We could not compare the new processes to the control (prior method), since the control process did not yield enough sample to test this functional property.

EXAMPLE 2

Starting material: Air-desolventized, hexane-defatted white flakes (IA 2020 variety, 1999 harvest) were produced in the pilot plant of the Center for Crops Utilization Research, Iowa State University. The defatted flakes were milled with a Krups grinder achieving 100% of the material passing through a 50-mesh screen. The protein content of the flour was 57.3% on a dry weight basis, protein PDI (Protein Dispersibility Index) of the flour was 93.8 as determined by Silliker Laboratories (Minnetonka, Minn.).

Soy protein fractionation (Wu procedure, prior method): The soy protein fractionation procedure utilized as the control in this study is one reported by Wu and others (1999) and is a modification of Nagano and others (1992). About 200 g of defatted soy flour was extracted with de-ionized water at 15:1 water-to-flour ratio, the pH was adjusted to 8.5 with 2N NaOH, and the resulting slurry was stirred for 1 hour. After centrifuging at 14,300×g for 30 minutes at 15° C., the protein extract (first extract) was decanted and the amount of insoluble fiber residue was determined and sampled for proximate composition. Sufficient NaHSO₃ was added to the resulting protein extract to achieve 10 mM SO₂ and the pH was adjusted to 6.4 with 2N HCl. The resulting slurry was stored at 4° C. for 12-16 hour and centrifuged at 7,500×g and 4° C. for 20 minutes. A glycinin-rich fraction was obtained as the precipitated curd. This fraction was redisolved with de-ionized water and adjusted to pH 7 with 2N NaOH, sampled, and stored in sealed containers at −80° C. until freeze-dried. The supernatant, second protein extract, was adjusted to 250 mM NaCl and pH 5 with 2N HCl, and the slurry was stirred for 1 hour. The slurry was then centrifuged at 14,000×g and 4° C. for 30 minutes. An intermediate fraction (a mixture of glycinin and β-conglycinin) was obtained as the precipitated curd; this fraction was treated as previously described. The supernatant, third protein extract, was diluted with de-ionized water in a ratio of two times the volume of the third protein extract, and the pH adjusted was to 4.8. The resulting slurry was centrifuged at 7,500×g and 4° C. for 20 minutes. The β-conglycinin-rich fraction was obtained as the precipitated curd. This fraction was treated as previously described, and the amount of supernatant (whey) was determined and sampled for proximate composition.

Calcium effects on the Wu soy protein fractionation procedure: To show the effects of replacing NaCl with Ca²⁺ salts the overall fractionation scheme was followed was described previously. The second protein extract, starting point for this example, was divided into nine aliquots of ˜150 g each. To each of these aliquots we added sufficient CaSO₄ or CaCl₂ to obtain 5, 10, 20, 50, 100, 200, 500, and 1000 mM Ca²⁺ and the previously described fractionation procedure was carried out. All procedures for both calcium salts were duplicated.

Modified Wu soy protein fractionation procedure: The soy protein fractionation procedure previously described was modified by introducing changes after obtaining the glycinin-rich fraction and starting with the second extract. The second protein extract was divided into nine aliquots of ˜150 g each. One aliquot had no salt and the fractionation procedure was followed as described before with the exception that no dilution step was employed to precipitate the β-conglycinin-rich fraction. The other eight aliquots were divided into two groups; CaCl₂ was added to obtain concentrations of 5, 10, 20, and 50 mM Ca²⁺ in one group and the fractionation procedure was followed as was previously described with the exception that no dilution step was employed to obtain the β-conglycinin-rich fraction; in the second group CaCl₂ was added to obtain concentrations of 5, 10, 20, and 50 mM Ca²⁺ and the pH was adjusted to 6.4 and the slurry was stirred for 1 hour. The slurries were centrifuged at 14,000×g and 4° C. for 30 minutes. An intermediate fraction (mixture of glycinin and β-conglycinin) was obtained as the precipitated curd. The supernatant, third protein extract, was adjusted to pH 4.8 with 2N HCl and without the addition of extra water. The resulting slurry was centrifuged at 7,500×g and 4° C. for 20 minutes. A β-conglycinin-rich fraction was obtained as the precipitated curd. This fraction was treated as was previously descried and the amount of supernatant (whey) was determined and sampled for proximate composition. Each treatment was duplicated.

New simplified soy protein fractionation procedure: Based on results obtained by the previously described fractionation method we developed a second soy protein fractionation procedure. About 200 g of defatted soy flour was extracted with de-ionized water at 15:1 water-to-flour ratio, the pH was adjusted to 8.5 with 2N NaOH, and the resulting slurry was stirred for 1 hour. After centrifuging at 14,300×g and 15° C. for 30 minutes, the protein extract (first extract) was decanted and the amount of insoluble fiber residue was determined and sampled for proximate composition. This extract was divided into eight aliquots of about 250 g each. A different treatment was applied to each of these extracts.

One aliquot was treated as described by the traditional modified Nagano process previously described (Wu and others 1999). The second extract was treated with no salts and pH adjusted to 6.4 with 2N HCl. The resulting slurry was stored at 4° C. for 12-16 hours and centrifuged at 14,000×g and 4° C. for 30 minutes. A glycinin-rich fraction was obtained as the precipitated curd and was neutralized and treated as above. The supernatant, second protein extract, was adjusted to pH 4.8 with HCl and the slurry stirred for 1 hour. The slurry was then centrifuged at 14,000×g and 4° C. for 30 minutes. A β-conglycinin-rich fraction was obtained as the precipitated curd. This fraction was treated as was previously described, and the amount of supernatant (whey) was determined and sampled for proximate composition. This process was designated as the 00 control.

The remaining six aliquots were treated as was previously described for the simplified fractionation procedure (00 control) but with the following modifications introduced before adjusting to pH 6.4. A third aliquot was treated with no NaHSO₃ and sufficient CaCl₂ to obtain 5 mM Ca²⁺; a fourth aliquot was treated with no NaHSO₃ and sufficient CaCl₂ to obtain 10 mM Ca²⁺. A fifth aliquot was treated with NaHSO₃ to achieve 5 mM SO₂ and CaCl₂ to obtain 5 mM Ca²⁺. A sixth aliquot was treated with sufficient NaHSO₃ to achieve 5 mM SO₂ and CaCl₂ to obtain 10 mM Ca²⁺. A seventh aliquot was treated with sufficient NaHSO₃ to achieve 10 mM SO₂ and CaCl₂ to obtain 5 mM Ca²⁺. An eighth aliquot was treated with sufficient NaHSO₃ to achieve 10 mM SO₂ concentration and CaCl₂ to obtain 10 mM Ca²⁺. All fractions obtained were adjusted to pH 7.0 with 2N NaOH and stored at −80° C. until they were freeze-dried. All treatments were duplicated.

Calcium effects on the Wu soy storage protein fractionation process: The solids yields of the glycinin-rich fraction were 13.1±0.6% and 12.9±0.3% for CaSO₄ and CaCl₂ examples, respectively, and the total protein yields for this fraction were 23.5±2.1% and 24.8±1.3% for CaSO₄ and CaCl₂ examples, respectively. The starting point for both examples was the second extract, which had a solids yield of 55.9±2.1% and 56.2±2.8%, and total protein yields of 53.1±1.2% and 53.0±2.0% for CaSO₄ and CaCl₂ examples, respectively.

TABLE 12
Yields of solids and total protein (%) for the Wu soy protein
fractionation procedure replacing NaCl with CaSO4 and CaCl2a
	Treatment
	CaSO4		CaCl2
	Fraction	Solids	Protein	Solids	Protein
	Intermediate
	0 mM Ca2+	25.9e	41.8a,b	26.7a,b	42.2b
	5 mM Ca2+	27.8e	42.4a	23.9b,c	46.6a
	10 mM Ca2+	28.5e	42.3a	27.7a	46.0a,b
	20 mM Ca2+	31.9d,e	41.4a,b	24.2b,c	44.6a,b
	50 mM Ca2+	32.1d	42.6a	25.0a,b,c	44.8a,b
	100 mM Ca2+	35.7c	42.1a	25.1a,b,c	45.3a,b
	200 mM Ca2+	37.2b,c	42.3a	23.3c	43.9a,b
	500 mM Ca2+	40.2b	40.1b	19.4d	42.7b
	1000 mM Ca2+	45.4a	42.7a	15.5e	42.8b
	LSD	3.6	2.0	2.9	3.5
	β-Conglycinin-rich
	0 mM Ca2+	3.1a	3.3a	4.5a	2.9a
	5 mM Ca2+	2.0b	0.3b	1.9b	0.4b
	10 mM Ca2+	1.6b,c	0.4b	1.6b	0.4b
	20 mM Ca2+	1.1b,c	1.1b	1.4b	0.5b
	50 mM Ca2+	1.0c	0.1b	0.9b	0.5b
	100 mM Ca2+	0.8c	0.2b	1.1b	0.7b
	200 mM Ca2+	0.9c	0.2b	0.7b	0.6b
	500 mM Ca2+	1.6b,c	1.2b	1.7b	1.2b
	1000 mM Ca2+	1.7b,c	1.1b	2.0b	1.1b
	LSD	1.0	1.1	1.4	0.9
	Whey
	0 mM Ca2+	29.7a	9.4e	28.1f	9.9b
	5 mM Ca2+	27.9a	11.2b	30.7e	10.5a,b
	10 mM Ca2+	29.5a	11.1b	31.2e	11.6a,b
	20 mM Ca2+	25.1b	11.2b	32.0d,e	11.6a,b
	50 mM Ca2+	24.8b	11.2b	31.9e	12.1a
	100 mM Ca2+	23.3b	12.0a,b	33.3d	11.9a
	200 mM Ca2+	20.9c	11.2b	34.8c	10.5a,b
	500 mM Ca2+	17.9d	12.2a,b	39.3b	12.0a
	1000 mM Ca2+	13.1e	13.5a	42.6a	11.9a
	LSD	2.4	1.9	1.4	2.0
	aN = 2.
	Means within a column for each fraction followed by different superscripts are significantly different at p < 0.05.
	LSD denotes least significant difference at p < 0.05.

Modified Wu soy protein fractionation procedure: To further show how Ca²⁺ can be used as a soy protein-fractionating agent we introduced several changes to the method of Wu and others (1999). Because of its higher solubility, we continued our examples using CaCl₂. Two different pHs were used (5.0 and 6.4) to precipitate the intermediate fraction. We also eliminated the dilution step prior to precipitating the β-conglycinin-rich fraction. As in the previous example the starting point for Ca²⁺ addition was the second extract obtained after the glycinin-rich fraction was precipitated.

TABLE 13
Yields (%) of solids and protein and protein composition (%) of fractions
obtained with the modified Wu soy protein fractionation procedurea.
Fraction	Flour	First Extract	Glycinin-rich	Second Extract
Yields
Solids	100.0	67.6 ± 1.2	12.5 ± 0.5	56.3 ± 1.8
Protein	100.0	75.0 ± 1.4	22.7 ± 0.4	52.9 ± 0.9
Storage Protein yield and protein composition
Storage protein	72.9 ± 0.4	77.8 ± 0.6	91.8 ± 0.2	79.8 ± 1.3
Glycinin	61.6 ± 0.4	57.3 ± 4.2	83.5 ± 0.2	31.7 ± 1.4
Acidic	60.1 ± 1.4	61.0 ± 0.7	52.4 ± 1.6	43.2 ± 0.6
Basic	39.9 ± 1.4	39.0 ± 0.7	47.6 ± 1.6	56.8 ± 0.6
β-Conglycinin	38.4 ± 0.4	42.7 ± 4.2	16.5 ± 0.2	68.3 ± 1.4
α′	33.6 ± 1.5	30.1 ± 0.3	0.0 ± 0.0	29.1 ± 1.9
α	33.5 ± 2.2	34.5 ± 1.4	48.7 ± 1.0	33.6 ± 0.8
β	32.9 ± 0.7	35.4 ± 1.1	51.2 ± 1.0	37.3 ± 0.7
aN = 2.
Means ± one standard deviation

TABLE 14
Yields (%) of solids and protein and protein composition (%) of fractions
obtained using the modified Wu soy protein fractionation procedurea
		Storage Proteins Yield
Fraction/Treatment	Fraction Yields	and Composition
(CaCl2, pH of int. fr. ppt)	Solids	Protein	Total	β-Conglycinin	Glycinin
Intermediate
0 mM CaCl2, pH 5.0	25.8c	41.8c	79.5a,b	64.1c,d	35.9c,d
5 mM CaCl2, pH 5.0	28.0a,b,c	46.2a	76.7b	61.4d,e	38.6b,c
10 mM CaCl2, pH 5.0	28.4a,b	46.0a	76.3b	65.2b,c	34.8d,e
20 mM CaCl2, pH 5.0	27.5a,b,c	44.5a,b	75.8b	63.6c,d	36.4c,d
50 mM CaCl2, pH 5.0	29.1a	44.0b	77.2b	63.4c,d	36.6c,d
5 mM CaCl2, pH 6.4	15.1e	22.8f	82.5a	37.7f	62.3a
10 mM CaCl2, pH 6.4	19.3d	28.1e	80.9a	59.5e	40.5b
20 mM CaCl2, pH 6.4	26.5b,c	38.6d	81.3a	68.7a,b	31.3e,f
50 mM CaCl2, pH 6.4	27.4a,b,c	40.8c	82.2a	70.2a	29.8f
LSD	2.3	2.0	3.3	3.7	3.7
β-Conglycinin-rich
0 mM CaCl2, pH 5.0	3.2d,e	2.9d	82.2b	89.9b	10.1d
5 mM CaCl2, pH 5.0	2.2e,f	0.6f	58.8g	72.5c	27.5c
10 mM CaCl2, pH 5.0	1.8e,f	0.6f	59.6g	70.1d	29.9b
20 mM CaCl2, pH 5.0	1.6e,f	1.6e,f	69.4f	62.7e	37.3a
50 mM CaCl2, pH 5.0	1.0f	0.5f	85.1a	89.2b	10.8d
5 mM CaCl2, pH 6.4	15.2a	24.7a	75.8d	100.0a	0.0e
10 mM CaCl2, pH 6.4	11.1b	18.0b	78.1c	100.0a	0.0e
20 mM CaCl2, pH 6.4	5.1c	7.2c	75.1d,e	100.0a	0.0e
50 mM CaCl2, pH 6.4	4.2c,d	5.5c	73.0e	100.0a	0.0e
LSD	1.9	2.1	2.2	1.6	1.6
Whey
0 mM CaCl2, pH 5.0	28.3c	9.2c	60.0f	23.4b	76.6c
5 mM CaCl2, pH 5.0	30.2a,b,c	10.1b,c	73.1d	11.3d	88.7a
10 mM CaCl2, pH 5.0	31.1a,b	11.6a,b	74.1c,d	10.4d	89.6a
20 mM CaCl2, pH 5.0	31.0a,b	12.1a	74.4c,d	11.4d	88.6a
50 mM CaCl2, pH 5.0	31.1a,b	12.1a	88.4a	19.7c	80.3b
5 mM CaCl2, pH 6.4	29.1b,c	9.7c	69.5e	10.7d	89.3a
10 mM CaCl2, pH 6.4	29.4a,b,c	9.4c	69.5e	11.2d	88.8a
20 mM CaCl2, pH 6.4	31.2a,b	9.8b,c	75.0c	9.0d	91.0a
50 mM CaCl2, pH 6.4	31.8a	9.9b,c	81.8b	30.4a	69.6d
LSD	2.5	1.9	1.9	3.1	3.1
aN = 2. Means within a column for each fraction followed by different superscripts are significantly different at p < 0.05.
LSD denotes least significant difference at p < 0.05;
int. fr. ppt. denotes intermediate fraction precipitation pH.

TABLE 15
Glycinin and β-conglycinin subunit composition (%) of
fractions obtained when using the modified Wu soy
protein fractionation procedurea
	β-Conglycinin Subunit	Glycinin Subunit
Fraction/Treatment	Composition	Composition
(CaCl2; pH of int. fr.ppt)	α′	α	β	Acidic	Basic
Intermediate
0 mM CaCl2, pH 5.0	28.0d	34.8a	37.2b,c	45.9b,c	54.1c,d
5 mM CaCl2, pH 5.0	29.5c,d	32.8a,b	37.7b,c	50.5a	49.5e
10 mM CaCl2, pH 5.0	30.2c,d	33.7a,b	36.1c	49.7a,b	50.3d,e
20 mM CaCl2, pH 5.0	30.6c,d	32.5b,c	36.9c	48.7a	51.3e
50 mM CaCl2, pH 5.0	29.9c,d	30.7c	39.3b	45.2c	54.8c
5 mM CaCl2, pH 6.4	32.1b,c	26.2d	41.7a	52.0a	48.0e
10 mM CaCl2, pH 6.4	33.9a,b	26.8d	39.3b	39.3d	60.7b
20 mM CaCl2, pH 6.4	34.9a,b	29.6c	35.5c	35.8d,e	64.2a,b
50 mM CaCl2, pH 6.4	36.0a	27.2d	36.8c	35.3e	64.7a
LSD	3.0	2.2	2.3	3.9	3.9
β-Conglycinin-rich
0 mM CaCl2, pH 5.0	19.2e,f	64.3a	16.5g	100.0a	0.0d
5 mM CaCl2, pH 5.0	20.3d,e	52.6b	27.1c,d	32.9c	67.1b
10 mM CaCl2, pH 5.0	20.9d	53.2b	25.9e	26.2d	73.8a
20 mM CaCl2, pH 5.0	18.2f	50.0c	31.8b	45.1b	54.9c
50 mM CaCl2, pH 5.0	32.1c	42.4e	25.5e	44.8b	55.2c
5 mM CaCl2, pH 6.4	34.7b	29.1g	36.2a	0.0e	0.0d
10 mM CaCl2, pH 6.4	37.4a	33.6f	29.0c	0.0e	0.0d
20 mM CaCl2, pH 6.4	38.7a	34.9f	26.4d,e	0.0e	0.0d
50 mM CaCl2, pH 6.4	32.3c	48.0d	19.7f	0.0e	0.0d
LSD	1.7	2.0	2.0	2.7	2.7
Whey
0 mM CaCl2, pH 5.0	0.0b	0.0c	100.0a	60.8a	39.2d,e
5 mM CaCl2, pH 5.0	0.0b	0.0c	100.0a	45.5e	54.5a
10 mM CaCl2, pH 5.0	0.0b	0.0c	100.0a	44.1e	55.9a
20 mM CaCl2, pH 5.0	0.0b	0.0c	100.0a	54.7b,c	45.3c,d
50 mM CaCl2, pH 5.0	0.0b	51.6a	48.4b	55.0b,c	45.0c,d
5 mM CaCl2, pH 6.4	0.0b	0.0c	100.0a	51.3c,d	48.7b,c
10 mM CaCl2, pH 6.4	0.0b	0.0c	100.0a	51.4c,d	48.6b,c
20 mM CaCl2, pH 6.4	0.0b	0.0c	100.0a	47.2d,e	52.8a,b
50 mM CaCl2, pH 6.4	25.8a	45.0b	29.2c	56.0b	44.0d
LSD	1.0	1.4	1.5	4.4	4.4
aN = 2. Means within a column for each fraction followed by different superscripts are significantly different at p < 0.05.
LSD denotes least significant difference at p < 0.05;
int. fr. ppt. denotes intermediate fraction precipitation pH.

New simplified soy storage protein fractionation procedure: We developed a new simplified fractionation method using mM amounts of CaCl₂ and sulfites as a reducing agent. The principal advantage of this new procedure is that it does not have an intermediate fraction, which is a mixture glycinin and β-conglycinin.

TABLE 16
Yields of solids and protein (%) and storage protein compositions (%) of
fractions obtained when using the new simplified fractionation procedurea
		Storage Proteins Yield
Fraction/Treatment	Fraction Yields	and Composition
(SO2 and CaCl2)	Solids	Protein	Total	β-Conglycinin	Glycinin
Flour	100.0	100.0	73.2 ± 0.2	38.1 ± 0.2	61.9 ± 0
First extract	69.9 ± 1.6	78.6 ± 2.0	78.5 ± 0.2	42.8 ± 0.7	57.2 ± 0.
Glycinin-rich
Wu	13.0d,e	27.8c	86.4a,b	16.2d	83.8b
Control	12.1e	21.2d	84.8b	26.0b	74.0d
0 mM SO2, 5 mM CaCl2	15.1c,d	25.1c	84.5b	26.0b	74.0d
0 mM SO2, 10 mM CaCl2	28.6a	47.1a	83.8b	35.3a	64.7e
5 mM SO2, 5 mM CaCl2	15.5c	27.8c	88.1a	14.8d	85.2b
5 mM SO2, 10 mM CaCl2	18.2b	31.2b	86.6a,b	24.4b	75.6d
10 mM SO2, 5 mM CaCl2	14.0c,d,e	25.5c	85.5a,b	11.9e	88.1a
10 mM SO2, 10 mM CaCl2	18.5b	31.9b	84.5b	20.5c	79.5c
LSD	2.3	3.1	2.9	1.9	1.9
Intermediate
Wu	7.8 ± 0.5	6.8 ± 0.2	77.1 ± 1.5	45.7 ± 1.1	54.3 ± 1.
β-Conglycinin-rich
Wu	10.1e	18.5f	85.1a,b	81.9a	18.1d
Control	26.6a	48.4a	81.1c	65.9c	34.1b
0 mM SO2, 5 mM CaCl2	25.5a,b	43.2b	86.8a	58.9d	41.1a
0 mM SO2, 10 mM CaCl2	13.3d	21.6e	83.5b	64.3c	35.7b
5 mM SO2, 5 mM CaCl2	23.6b	39.7c	79.8c	80.9a	19.1d
5 mM SO2, 10 mM CaCl2	21.5c	35.7d	77.6d	80.4a	19.6d
10 mM SO2, 5 mM CaCl2	24.9a,b	41.2b,c	80.5c	75.3b	24.7c
10 mM SO2, 10 mM CaCl2	21.2c	34.8d	77.5d	80.3a	19.7d
LSD	2.0	2.1	2.1	2.9	2.9
Whey
Wu	36.9a	12.8a	72.5b	30.9a	69.1e
Control	28.2d	9.2b	78.3a	16.0e	84.0a
0 mM SO2, 5 mM CaCl2	31.2b,c	9.8b	66.9c	24.3b,c	75.7c,d
0 mM SO2, 10 mM CaCl2	29.9c,d	10.5a,b	62.6d	23.5b,c,d	76.5b,c
5 mM SO2, 5 mM CaCl2	32.7b	10.5a,b	59.3e	25.8b	74.2d
5 mM SO2, 10 mM CaCl2	32.0b,c	11.8a,b	61.7d	21.0d	79.0b
10 mM SO2, 5 mM CaCl2	32.8b	11.6a,b	61.8d	24.0b,c	76.0c,d
10 mM SO2, 10 mM CaCl2	32.1b,c	11.8a,b	61.8d	22.8c,d	77.2b,c
LSD	2.8	2.8	1.9	3.0	3.0
aN = 2. Means within a column for each fraction followed by different superscripts are significantly different at p < 0.05.
LSD denotes least significant difference at p < 0.05.
LSD denotes least significant difference at p < 0.05;
Wu, Wu process;
Control, 0 mM SO2 and 0 mM CaCl2.

TABLE 17
Glycinin and β-conglycinin subunit compositions (%) of fractions
obtained using the new simplified fractionation procedurea
Fraction/Treatment	β-Conglycinin	Glycinin
(SO2 and CaCl2)	α′	α	β	Acidic	Basic
Flour	33.5 ± 0.3	35.0 ± 0.2	31.5 ± 0.1	58.9 ± 0.3	41.1 ± 0.3
First extract	30.1 ± 0.1	34.7 ± 0.3	35.2 ± 0.2	58.0 ± 1.6	42.0 ± 1.6
Glycinin-rich
Wu	0.0d	49.3a	50.7a	56.0d	44.0a
Control	28.6a,b	32.0c	39.4d	60.3c,d	39.7a,b
0 mM SO2, 5 mM CaCl2	27.7b,c	32.2c	40.1d	60.8b,c	39.2b,c
0 mM SO2, 10 mM CaCl2	30.1a	34.7b	35.2e	58.7c,d	41.3a,b
5 mM SO2, 5 mM CaCl2	28.7a,b	27.3d	44.0c	62.6b,c	37.4b,c
5 mM SO2, 10 mM CaCl2	29.3a,b	26.6d,e	44.1c	65.0a,b	35.0c,d
10 mM SO2, 5 mM CaCl2	26.1c	27.7d	46.2b	68.6a	31.4d
10 mM SO2, 10 mM CaCl2	28.3a,b	25.3e	46.4b	68.3a	31.7d
LSD	1.9	2.1	1.8	4.4	4.4
Intermediate
Wu	26.0 ± 1.0	32.2 ± 0.8	41.8 ± 1.2	44.4 ± 0.9	55.6 ± 0.9
β-Conglycinin-rich
Wu	28.7d	37.1b	34.1a	45.5c	54.5b
Control	33.6a	33.8c	32.6a	33.6d	66.4a
0 mM SO2, 5 mM CaCl2	30.2c,d	39.5a	30.3b	43.5c	56.5b
0 mM SO2, 10 mM CaCl2	32.5a,b	40.1a	27.4c	41.9c	58.1b
5 mM SO2, 5 mM CaCl2	30.9b,c	35.8b	33.3a	54.2a,b	45.8c,d
5 mM SO2, 10 mM CaCl2	29.9c,d	37.5b	32.6a	52.2b	47.8c
10 mM SO2, 5 mM CaCl2	31.1b,c	35.7b	33.2a	45.0c	55.0b
10 mM SO2, 10 mM CaCl2	32.4a,b	37.1b	30.5b	57.0a	43.0d
LSD	2.0	2.0	1.9	4.8	4.8
Whey
Wu	0.0d	46.8a	53.2e	57.8a	42.2d
Control	0.0d	0.0b	100.0a	49.2b	50.8c
0 mM SO2, 5 mM CaCl2	45.8a	0.0b	54.2d,e	38.6d	61.4a
0 mM SO2, 10 mM CaCl2	42.1b	0.0b	57.9c	38.6d	61.4a
5 mM SO2, 5 mM CaCl2	43.3b	0.0b	56.7c,d	44.2c	55.8b
5 mM SO2, 10 mM CaCl2	42.8b	0.0b	57.2c	39.9d	60.1a
10 mM SO2, 5 mM CaCl2	41.3b	0.0b	58.7b,c	39.6d	60.4a
10 mM SO2, 10 mM CaCl2	38.7c	0.0b	61.3b	37.7d	62.3a
LSD	2.1	0.4	2.6	3.3	3.3
aN = 2. Means within a column for each fraction followed by different superscripts are significantly different at p < 0.05.
LSD denotes least significant difference at p < 0.05;
Wu, Wu process;
Control, 0 mM SO2 and 0 mM CaCl2.

These examples clearly show calcium can be effectively used to fractionate soybean storage proteins. The fractionation process with CaCl₂ is highly pH dependent. CaCl₂ can be effectively used to precipitate the remaining glycinin from solution in a three steps fraction process when this precipitation is made at pH 6.4. No additional dilution is needed to obtain the β-conglycinin-rich fraction. The addition of sulfites plays an important role in the effectiveness of Ca²⁺ as a fractionating agent. A new procedure was developed, avoiding an intermediate fraction, for a two-step fractionation process that yielded significantly higher amounts of glycinin-rich and β-conglycinin-rich fractions with similar purities to those obtained by previous soy protein fractionation procedures.

EXAMPLE 3

Materials: Samples were prepared from air-desolventized, hexane-defatted white flakes (from IA2020 variety, 1999 harvest) produced in the pilot plant of the Center for Crops Utilization Research, Iowa State University. These flakes had 57.3% protein, and 1922 μg/g total isoflavones as determined in our laboratory and 93.8 protein dispersibility index (PDI) as determined by Silliker Laboratories (Minnetonka, Minn.). The flakes were milled until 100% of the material obtained passed through a 50-mesh screen by using a Krups grinder.

Modified Nagano's (Wu) soy protein fractionation procedure: The soy protein fractionation procedure utilized the same control as is described in the previous example.

New simplified soy protein fractionation procedure: About 100 g of defatted soy flour was extracted with de-ionized water at 15:1 water-to-flour ratio, the pH was adjusted to 8.5 with 2N NaOH, and the resulting slurry was stirred for 1 hour. After centrifuging at 14,300×g and 15° C. for 30 minutes, the protein extract (first extract) was decanted and the amount of insoluble fiber residue was determined and sampled for proximate composition. This extract was combined with sufficient NaHSO₃ and CaCl₂ to obtain 5 mM SO₂ and 5 mM Ca²⁺ and the pH was adjusted to 6.4 with 2N HCl. The resulting slurry was stored at 4° C. for 12-16 hour (this treatment is denoted as New 4C) in one case, and stirred for 1 hour at ˜25° C. (this treatment is denoted as New RT) in the other case. In both cases, protein fractionation was continued by centrifuging the slurry at 14,000 kg and 4° C. for 30 minutes. A glycinin-rich fraction was obtained as the precipitated curd; this curd was neutralized and treated as described before. The supernatant, second protein extract, was adjusted to pH 4.8 with HCl and the slurry was stirred for 1 hour. The slurry was centrifuged at 14,000×g and 4° C. for 30 minutes. A β-conglycinin-rich fraction was obtained as the precipitated curd. This fraction was treated as previously described, and the amount of supernatant (whey) was determined and sampled for proximate composition. Both treatments (New 4C and New PT) were replicated in duplicate and means reported.

Protein profile results were calculated as % composition; total storage protein in a given fraction=[(sum of storage protein subunit bands)/(sum of all bands)]×100, fraction purity/composition=[(sum of subunit bands)/(sum of storage protein bands)], and subunit composition of a specific protein=[(subunit band)/(sum of subunits for the specific protein)]. All measurements were replicated at least four times and means were reported.

TABLE 18
Yields and compositions (dry basis) of soy protein fractions prepared by using
the Wu and new proceduresa.
			Isoflavone	Protein		Isoflavone
	Solids	Protein	Yield	Content	Ash	Content
Fraction/Treatment	Yield (%)	Yield (%)	(%)	(%)	(%)	(μg/g)
Wu glycinin	11.6b	22.3c	9.6c	96.7b	3.9a	1591c
N4C glycinin	15.5a	24.4b	20.5a	98.9a	3.2b	2547a
NRT glycinin	15.7a	29.9a	15.9b	96.6b	3.0c	1942b
LSD	1.2	1.8	2.0	0.9	0.2	155
Wu intermediate	18.2 ± 1.0	26.8 ± 1.3	20.9 ± 1.2	80.3 ± 1.2	14.3 ± 0.2	2213 ± 130
Wu β-conglycinin	11.5b	18.5c	3.3c	92.2a	10.1a	548c
N4C β-conglycinin	23.1a	37.1a	37.5a	90.0b	6.0b	3120a
NRT β-conglycinin	23.3a	32.4b	34.8b	91.2a	5.3c	2868b
LSD	2.4	1.7	2.5	1.2	0.3	184
LSDb	2.2	1.9	2.6	1.4	0.2	192
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05.
Wu denotes fractions produced with the Wu procedure;
N4C, fractions produced with the new fractionation procedure with a chilling step;
NRT, fractions produced with the new fractionation procedure without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD, least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 19
Protein compositions and subunit profiles of the protein fractions
prepared by using the Wu and new proceduresa.
	Storage
	Protein	β-Conglycinin	Glycinin
	in		Subunit		Subunit
Fraction/	Fraction		Composition (%)		Composition (%)
Treatment	(%)	%	α′	α	β	%	A	B
Wu glycinin	89.0a	16.3b	0.0b	49.5a	50.5a	83.7a	54.1b	45.9a
N4C glycinin	94.2a	19.0b	26.9a	25.0c	48.1b	81.0a	64.1a	35.9b
NRT glycinin	93.8a	28.6a	28.0a	30.7b	41.3c	71.4b	57.1b	42.9a
LSD	7.2	5.2	1.5	2.2	2.3	5.2	5.6	5.6
Wu intermediate	79.1 ± 2.0	45.3 ± 2.3	23.7 ± 1.2	31.7 ± 2.1	44.6 ± 1.0	54.7 ± 2.3	46.3 ± 4.0	53.7 ± 4.0
Wu β-conglycinin	85.2a	83.8b	28.7a	36.7a	34.6a	16.2b	43.5a	56.5c
N4C β-conglycinin	81.9b	85.6a	27.3a	38.0a	34.7a	14.4c	39.8b	60.2b
NRT β-conglycinin	84.3a	78.6c	29.4a	38.5a	32.0b	21.4a	31.9c	68.1a
LSD	2.2	0.4	2.8	3.6	2.2	0.4	1.8	1.8
LSDb	4.5	2.6	3.4	2.1	3.8	2.6	3.7	3.7
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05.
Glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction;
A, acidic subunits of glycinin;
B, basic subunits of glycinin;
Wu, fractions produced by using the Wu procedure;
N4C, fractions produced by using the new fractionation procedure with a chilling step;
NRT, fractions produced by using the new fractionation procedure without a chilling step; and LSD, least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 20

Isoflavone profiles of protein fractions prepared by using the Wu and new proceduresa.

Isoflavone Profile (μmol/g)

Fraction/Treatment

Din

MDin

AcDin

Dein

Glyin

MGly

Glyein

Gin

MGin

AcGin

Gein

Total

Flour

0.73

2.18

0.05

0.13

0.22

0.25

0.00

1.01

2.44

0.08

0.10

7.20

Wu glycinin

0.20a

0.73b

0.03a

0.59b

0.13a

0.22a

0.25a

0.66a

1.69c

0.36a

0.96c

5.92c

N4C glycinin

0.24a

1.42b

0.05a

0.84a

0.09b

0.17b

0.11b

0.69a

3.99a

0.09c

1.34a

9.52a

NRT glycinin

0.22a

1.91a

0.05a

0.60b

0.07b

0.13c

0.08c

0.57a

2.85b

0.17b

1.09b

7.26b

LSD

0.08

0.10

0.13

0.02

0.03

0.01

0.01

0.19

0.05

0.02

0.10

0.28

Wu intermediate

0.44

0.90

0.05

1.09

0.25

0.25

0.31

1.31

1.82

0.15

1.60

8.26

Wu β-conglycinin

0.07b

0.20c

0.03c

0.33c

0.05b

0.07b

0.09b

0.17b

0.36b

0.07b

0.58c

2.05b

N4C β-conglycinin

0.40a

2.48a

0.05b

1.13a

0.11a

0.22a

0.11a

1.11a

4.20a

0.08b

1.79a

11.68a

NRT β-conglycinin

0.42a

2.25b

0.09a

0.88b

0.12a

0.21a

0.09b

1.13a

4.02a

0.18a

1.33b

10.73a

LSD

0.06

0.21

0.01

0.19

0.01

0.01

0.02

0.26

0.58

0.04

0.38

1.39

LSDb

0.15

0.13

0.07

0.10

0.06

0.02

0.02

0.37

0.30

0.02

0.19

0.82

aN = 2. Means within a column followed by different superscripts are significant different at p < 0.05.

Din denotes daidzin;

MDin, malonyldaidzin;

AcDin, acetyldaidzin;

Dein, daidzein;

Gly, glycitin;

MGly, malonylglycitin;

Glyein, glycitein;

Gin, genistin;

MGin, malonylgenistin;

AcGin, acetylgenistin; and

Gein, genistein.

Glycinin denotes glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction;

Wu, fractions produced by using the Wu procedure;

N4C, fractions produced by using the new fractionation procedure with a chilling step; NRT, fractions produced by using the new fractionation procedure without a chilling step; and

LSD, least significant difference at p < 0.05.

bLeast significant difference for comparing all fractions within a column.

TABLE21
Thermal behaviors of protein fractions prepared by using the Wu and new proceduresa.
			β-Conglycinin	Glycinin	Total
	β-Conglycinin	Glycinin	Enthalpy	Enthalpy	Enthalpy
Fraction/Treatment	Td (° C.)	Td (° C.)	(mJ/mg)	(mJ/mg)	(mJ/mg)
Wu glycinin	74.7a	89.1a	0.32a	15.65b	15.97b
N4C glycinin	73.3a	91.0a	0.61a	19.23a	19.84a
NRT glycinin	72.8a	91.3a	0.81a	19.33a	20.15a
LSD	2.0	2.1	0.55	2.31	1.16
Wu intermediate	74.8 ± 1.1	93.1 ± 0.5	1.48 ± 0.37	2.91 ± 0.64	4.31 ± 0.59
Wu β-conglycinin	75.1a	88.9c	10.64a	0.06b	10.70a
N4C β-conglycinin	75.1a	89.8b	6.47b	0.55a,b	7.01b
NRT β-conglycinin	74.7a	90.8a	4.96c	1.19a	6.15b
LSD	1.0	0.9	1.12	0.92	1.38
LSDb	1.6	1.5	0.93	1.06	1.23
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation procedure with a chilling step; NRT, fractions produced with the new fractionation procedure without a chilling step; glycinin, glycinin-rich fraction; β-con., β-conglycinin-rich
# fraction; Inter., intermediate fraction; and LSD, least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 22
Solubilities and surface hydrophobicities of protein fractions prepared
by using the Wu and new proceduresa.
		Solubility	Surface Hydrophobicity
	Fraction/Treatment	(%)	(dimensionless)
	Wu glycinin	88.1a	160a
	N4C glycinin	85.2b	161a
	NRT glycinin	80.5c	153a
	LSD	2.5	39
	Wu intermediate	39.7 ± 2.1	156 ± 22
	Wu β-conglycinin	93.8a	178b
	N4C β-conglycinin	71.8c	226a
	NRT β-conglycinin	80.5b	187b
	LSD	5.1	35
	LSDb	3.9	39
	aN = 2.
	Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05.
	Wu denotes fractions produced with the Wu procedure;
	N4C, fractions produced with the new fractionation procedure with a chilling step;
	NRT, fractions produced with the new fractionation procedure without a chilling step;
	glycinin, glycinin-rich fraction;
	β-conglycinin, β-conglycinin-rich fraction; and
	LSD, least significant difference at p < 0.05.
	bLeast significant difference for comparing all fractions within a column.

TABLE 23
Emulsification properties of protein fractions prepared by
using the Wu and new proceduresa.
	Emulsification
	Capacity	Emulsification
	(g of oil	Activity	Emulsification
	emulsified/	(absorbance	Stability Index
Fraction/Treatment	g of product)	at 500 nm)	(dimensionless)
Wu glycinin	351c	0.152a	84a
N4C glycinin	876a	0.140a	73a
NRT glycinin	684b	0.149a	68a
LSD	28	0.015	22
Wu intermediate	232 ± 29	0.168 ± 0.026	62 ± 26
Wu β-conglycinin	586b	0.306a	194a
N4C β-conglycinin	678a	0.276b	192a
NRT β-conglycinin	647a	0.244c	151b
LSD	35	0.028	38
LSDb	30	0.022	32
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation procedure with a chilling step; NRT, fractions produced with the new fractionation procedure without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD, least
# significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 24
Foaming properties of the protein fractions prepared by using
the Wu and new proceduresa.
	Foaming	Foaming
	Capacity	Stability (k =	Rate of Foaming
Fraction/Treatment	(mL/mL)	1/(mL * min))	(Vi = mL/min)
Wu glycinin	0.964c	0.089c	2.0c
N4C glycinin	1.428b	0.075b	8.4b
NRT glycinin	1.654a	0.068a	10.3a
LSD	0.159	0.006	1.9
Wu intermediate	0.958 ± 0.059	0.004 ± 0.001	17.2 ± 3.1
Wu β-conglycinin	1.069c	0.018b	12.4c
N4C β-conglycinin	1.597b	0.008a	32.0b
NRT β-conglycinin	1.648a	0.007a	34.5a
LSD	0.124	0.008	2.0
LSDb	0.130	0.009	2.3
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation procedure with a chilling step; NRT, fractions produced with the new fractionation procedure without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD, least
# significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

Dynamic viscosity: Dynamic viscosity is characterized by two factors: the flow consistency index (K), which is a measure of how much energy the system is taking up to flow; and the flow behavior index (n), which is a measure of how far the system behaves from an ideal Newtonian fluid.

TABLE 25
Dynamic viscosities of protein fractions prepared by using the
Wu and new proceduresa.
	Flow Consistency	Flow Behavior Index
Fraction/Treatment	Index (K = mPa * s)	(n, dimensionless)
Wu glycinin	0.010a	0.925a
N4C glycinin	0.011a	0.867a
NRT glycinin	0.010a	0.917a
LSD	0.008	0.079
Wu intermediate	0.167 ± 0.027	0.739 ± 0.051
Wu β-conglycinin	0.617a	0.471c
N4C β-conglycinin	0.521b	0.585b
NRT β-conglycinin	0.070c	0.789a
LSD	0.082	0.058
LSDb	0.049	0.067
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation procedure with a chilling step; NRT, fractions produced with the new fractionation procedure without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD, least
# significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

EXAMPLE 4

Starting materials: Starting material, hexane-defatted HS/LS white flakes were prepared from HS/LS soybeans (Low Stachyose, Lot-980B0001 OPTIMUM, 1999 crop years, Pioneer-DuPont, Johnston, Iowa), in the pilot plant at the Center for Crops Utilization Research. The white flakes were milled with a Krups grinder (Distrito Federal, Mexico) until 100% of the material obtained passed through a 50-mesh screen. The HS/LS defatted soy flour contained 58.3% protein with 95.0 protein dispersibility index.

Wu soybean storage protein fractionation procedure: This procedure was performed as described in Example 3.

New simplified fractionation procedure: This procedure was performed as described in Example 3.

TABLE 26
Yields and compositions (dry basis) of soy protein fractions
prepared by using the Wu and new proceduresa.
	Solids	Protein	Protein
	Yield	Yield	Content	Ash
Fraction/Treatment	(%)	(%)	(%)	(%)
Wu glycinin	15.4b	31.7a	96.4a	4.1a
N4C glycinin	18.0a	25.7b	97.3a	3.6b
NRT glycinin	14.3b	25.5b	94.7a	3.4b
LSD	1.8	3.5	4.4	0.3
Wu intermediate	8.8 ± 0.3	15.9 ± 0.7	80.9 ± 0.7	14.8 ± 0.1
Wu β-conglycinin	10.5c	22.3b	95.6a	11.2a
N4C β-conglycinin	20.5b	29.3a	92.2b	6.1b
NRT β-conglycinin	22.2a	28.7a	92.0b	5.8b
LSD	1.1	3.3	1.4	0.5
LSDb	1.1	2.4	2.3	0.3
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD,
# least significant difference at p < 0.05.
bLeast significant difference for comparison of all fractions within a column.

TABLE 27
Protein compositions and subunit profiles (%) of protein fractions prepared
by using the Wu and new proceduresa.
	Storage	β-Conglycinin	Glycinin
Fraction/	Protein in		Subunit Composition (%)		Subunit Composition (%)
Treatment	Fraction (%)	%	α′	α	β	%	A	B
Wu glycinin	100.0a	0.0c	0.0b	0.0b	0.0b	100.0a	63.6a	36.4c
N4C glycinin	88.9b	20.0b	29.7a	22.4a	48.0a	80.0b	53.5c	46.5a
NRT glycinin	81.5c	26.7a	23.3a	24.2a	52.5a	73.3c	57.2b	42.8b
LSD	0.7	3.1	8.3	3.0	6.3	3.1	2.1	2.1
Wu intermediate	69.6 ± 2.3	51.0 ± 3.6	28.6 ± 1.0	28.0 ± 0.9	43.4 ± 0.2	49.0 ± 3.6	45.1 ± 3.3	54.9 ± 3.3
Wu β-conglycinin	100.0a	100.0a	32.7a	38.5a	28.8b	0.0b	0.0b	0.0b
N4C β-conglycinin	78.2c	73.1b	29.5a	32.6a,b	37.9a	26.9a	49.5a	50.5a
NRT β-conglycinn	81.2b	71.9b	30.9a	28.9b	40.1a	28.1a	46.7a	53.3a
LSD	0.3	1.5	10.7	6.4	4.7	1.5	3.4	3.4
LSDb	2.1	3.6	6.7	3.5	3.8	3.6	3.6	3.6
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu procedure; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin,
#β-conglycinin-rich fraction; A, acidic subunits of glycinin; B, basic subunits of glycinin; and LSD, least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 28
Thermal behaviors of protein fractions prepared by using the Wu and new proceduresa.
			β-Conglycinin	Glycinin	Total
	β-Conglycinin	Glycinin	Enthalpy	Enthalpy	Enthalpy
Fraction/Treatment	Td (° C.)	Td (° C.)	(mJ/mg)	(mJ/mg)	(mJ/mg)
Wu glycinin	74.9a	89.5b	0.26b	15.96b	16.21b
N4C glycinin	73.8a,b	91.5a	0.51b	18.65a	19.16a
NRT glycinin	73.5b	91.3a	1.33a	18.62a	19.96a
LSD	1.3	1.0	0.47	1.70	2.10
Wu Intermediate	75.5 ± 0.3	93.6 ± 0.2	1.06 ± 0.13	3.06 ± 0.10	4.08 ± 0.09
Wu β-conglycinin	75.3a	90.0b	10.33a	0.17c	10.47a
N4C β-conglycinin	75.8a	89.8b	6.48b	1.03b	7.50b
NRT β-conglycinin	75.3a	91.7a	5.35b	1.77a	7.13b
LSD	1.4	1.4	1.25	0.37	1.54
LSDb	0.9	0.9	0.66	0.85	1.27
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu process; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin,
# β-conglycinin-rich fraction; Intermediate, intermediate fraction; Td, peak denaturation temperature; and LSD, least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 29
Solubilities and surface hydrophobicities of protein fractions
prepared by using the Wu and new proceduresa.
			Surface
		Solubility	Hydrophobicity
	Fraction/Treatment	(%)	(dimensionless)
	Wu glycinin	88.9a	152a
	N4C glycinin	92.9a	148a
	NRT glycinin	93.2a	154a
	LSD	5.6	33
	Wu intermediate	41.6 ± 0.8	179 ± 5
	Wu β-conglycinin	92.8a	185a
	N4C β-conglycinin	75.9b	180a
	NRT β-conglycinin	70.4b	130b
	LSD	6.2	23
	LSDb	4.1	20
	aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different p < 0.05. Wu denotes fractions produced with the Wu process; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD,
	# least significant difference at p < 0.05.
	bLeast significant difference for comparing all fractions within a column.

TABLE 30
Emulsification properties of protein fractions prepared by
using the Wu and new proceduresa.
	Emulsification
	Capacity	Emulsification
	(g of oil	Activity	Emulsification
	emulsified/	(absorbance	Stability Index
Fraction/Treatment	g of product)	at 500 nm)	(dimensionless)
Wu glycinin	307c	0.155a,b	76b
N4C glycinin	618a	0.177a	103a
NRT glycinin	547b	0.151b	83a,b
LSD	62	0.026	22
Wu intermediate	219 ± 5	0.194 ± 0.012	69 ± 6
Wu β-conglycinin	612a	0.311a	216a
N4C β-conglycinin	564b	0.301a	216a
NRT β-conglycinin	633a	0.322a	240a
LSD	41	0.038	147
LSDb	36	0.025	73
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu process; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD,
# least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

TABLE 31
Foaming properties of protein fractions prepared by
using the Wu and new proceduresa.
	Foaming	Foaming
	Capacity	Stability (k =	Rate of Foaming
Fraction/Treatment	(mL/mL)	1/(mL * min))	(Vi = mL/min)
Wu glycinin	1.090c	0.092a	2.3a
N4C glycinin	1.300b	0.173b	4.4a
NRT glycinin	1.514a	0.164b	5.0a
LSD	0.083	0.035	2.9
Wu intermediate	1.141 ± 0.062	0.005 ± 0.001	21.9 ± 0.7
Wu β-conglycinin	1.184c	0.018a	13.7b
N4C β-conglycinin	1.396b	0.035b	14.2b
NRT β-conglycinin	1.671a	0.012a	30.4a
LSD	0.186	0.007	4.5
LSDb	0.113	0.017	2.6
aN = 2. Means within a column for a specific fraction followed by different superscripts are significantly different at p < 0.05. Wu denotes fractions produced with the Wu process; N4C, fractions produced with the new fractionation process with a chilling step; NRT, fractions produced with the new fractionation process without a chilling step; glycinin, glycinin-rich fraction; β-conglycinin, β-conglycinin-rich fraction; and LSD,
# least significant difference at p < 0.05.
bLeast significant difference for comparing all fractions within a column.

EXAMPLE 5

The new fractionation method was used with Gas-Supported Screw Pressed partially defatted soybean cake. The starting cake was grinded in a Krups grinder until 100% of the soybean material passed through a mesh 50. The resulting flour had a protein content of 53.75%, a fat content of 4.6%, both on a dry basis, and a PDI of 54.5 as determined by Silliker Laboratories.

The new fractionation method was performed with this starting material. 100 g of cake was extracted with water at a ratio of 15:1 (treatment # 1) and 10:1 (treatment 2) and the pH of the slurry adjusted to 8.5 as described in previous examples. After centrifugation the respective protein extracts were added with sufficient NaHSO₃ and CaCl₂ as to obtain a 10 mM concentration of each salt in the extract and the pH was adjusted to 6.4, the resulting slurry centrifuged obtaining a glycinin-rich precipitate and a β-conglycinin-rich extract, which was father adjusted to a pH of 4.6 and centrifuged to obtain a β-conglycinin-rich precipitate. All resulting precipitates were re-dissolved in water and neutralized with dilute alkali to a pH of 7.0.

The resulting yields of solids, protein, protein contents and purities for protein fractions are shown in Table 32.

TABLE 32
Fraction yields and compositions of new fractionation procedures
using gass supported screw pressed partially defatted soybean cake.
	Solids	Protein	Protein
	Yield	Yield	Content	Puritya
Treatment/Fraction	(%)	(%)	(%)	(%)
Treatment #1
Glycinin-rich	14.1	25.7	97.9	87.7
β-conglycinin-rich	17.5	29.1	89.3	70.4
Total	31.6	54.8
Treatment #2
Glycinin-rich	13.3	24.5	98.8	91.3
β-conglycinin-rich	17.7	29.5	89.6	63.4
Total	31.0	54.0
aPurity expressed as % of storage protein present in said fraction

EXAMPLE 6

The potential of the new fractionation procedure using alternative reducing agents, multi-valent salts, EDTA, and pHs is shown in this example. The starting material was hexane-defatted and air desolventized white flakes from soybeans. The flakes were milled to obtain flour that passed through a #50 mesh screen. The protein content of said flour was 56.5%, the fat content 0.7% and had a PDI of 79.33 as determined by Silliker Laboratories.

All processes had the same starting step, the meal was extracted with de-ionized water at flour-to-water ratio of 1:10; the pH was adjusted to 8.5. The resulting slurry was stirred at 25° C., and after 1 hour the slurry was centrifuged at 14,000×g and 25° C. for 30 minutes to separate the spent flour from the protein extract. The resulting protein extract, yielding 65.6% of the protein originally present in the flour, was divided in twelve aliquots.

To each of these aliquots a combination of alternative reducing agents, multi-valent salts, and/or EDTA was added at different concentrations, the resulting pHs of the slurries were adjusted to different extents to obtain the glycinin-rich precipitate, and stirred for 15 minutes. After this initial stirring, all samples were placed overnight in a cold room at 4° C. The next day the extracts were stirred again and centrifuged at 14,000×g and 4° C. for 30 minutes, obtaining a glycinin-rich precipitate and a β-conglycinin-rich supernatant. The supernatant was adjusted to pH 4.6 in all cases and centrifuged again under the same conditions, recovering a β-conglycinin-rich curd, and an extract that we termed whey.

Treatments were as follows:

• • Treatment #1 New fractionation with addition of 5 mM of SO₂ and 5 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 6.0.
  • Treatment #2 New fractionation with addition of 10 mM of SO₂ and 10 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 6.4.
  • Treatment #3 New fractionation with addition of 5 mM of SO₂ and 5 mM of Mg²⁺. The pH for obtaining the glycinin-rich curd was 6.4.
  • Treatment #4 New fractionation with addition of 5 mM of SO₂ and 5 mM of Mg²⁺. The pH for obtaining the glycinin-rich curd was 5.8.
  • Treatment #5 New fractionation with addition of 10 mM of SO₂ and 10 mM of Mg²⁺. The pH for obtaining the glycinin-rich curd was 6.0.
  • Treatment #6 New fractionation with addition of 5 mM of SO₂ and 5 mM of EDTA. The pH for obtaining the glycinin-rich curd was 5.6.
  • Treatment #7 New fractionation with addition of 10 mM of SO₂ and 10 mM of EDTA. The pH for obtaining the glycinin-rich curd was 5.8.
  • Treatment #8 New fractionation with addition of 10 mM of SO₂ and 10 mM of EDTA. The pH for obtaining the glycinin-rich curd was 5.6.
  • Treatment #9 New fractionation with addition of 5 mM of ascorbic acid and 5 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 6.4.
  • Treatment #10 New fractionation with addition of 5 mM of ascorbic acid and 5 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 5.6.
  • Treatment #11 New fractionation with addition of 10 mM of ascorbic acid and 10 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 6.4.
  • Treatment #12 New fractionation with addition of 5 mM of L-cystine and 5 mM of Ca²⁺. The pH for obtaining the glycinin-rich curd was 6.4.

The resulting yields of solids, protein, protein contents and purities for protein fractions obtained are shown in Table 33.

TABLE 33
Fraction yields and compositions of new fractionation
procedure utilizing alternative reducing agents,
multi-valent salts, EDTA and pHs.
	Solids	Protein	Protein
	Yield	Yield	Content	Puritya
Treatment/Fraction	(%)	(%)	(%)	(%)
Treatment #1
Glycinin-rich	17.8	30.3	96.1	88.9
β-Conglycinin-rich	+UZ,17/20 16.2	26.3	91.7	71.7
Total	34.0	56.6
Treatment #2
Glycinin-rich	15.0	26.3	98.9	91.0
β-Conglycinin-rich	18.1	29.4	91.7	71.9
Total	33.1	55.7
Trearment #3
Glycinin-rich	13.5	23.7	99.1	85.6
β-Conglycinin-rich	20.1	32.7	91.8	68.6
Total	33.6	56.4
Treatment #4
Glycinin-rich	19.6	33.5	96.6	82.2
β-Conglycinin-rich	16.7	26.8	90.7	73.3
Total	36.3	60.3
Treatment #5
Glycinin-rich	18.0	31.3	98.4	84.3
β-Conglycinin-rich	16.1	26.8	94.2	72.4
Total	34.1	58.1
Treatment #6
Glycinin-rich	19.5	33.1	96.0	83.6
β-Conglycinin-rich	15.2	25.1	93.2	75.5
Total	34.7	58.2
Treatment #7
Glycinin-rich	15.5	27.0	98.3	83.3
β-Conglycinin-rich	16.3	27.0	93.6	69.9
Total	31.8	54.0
Treatment #8
Glycinin-rich	18.9	32.3	96.7	81.3
β-Conglycinin-rich	12.9	21.1	92.6	75.8
Total	31.8	53.4
Treatment #9
Glycinin-rich	13.5	23.7	99.2	88.8
β-Conglycinin-rich	20.4	33.2	92.0	67.8
Total	33.9	56.9
Treatment #10
Glycinin-rich	26.3	45.3	97.3	69.1
β-Conglycinin-rich	7.4	12.3	94.1	70.6
Total	33.7	57.6
Treatment #11
Glycinin-rich	18.6	32.3	98.0	71.0
β-Conglycinin-rich	14.4	24.3	95.5	68.7
Total	33.0	56.6
Treatment #12
Glycinin-rich	13.8	23.7	97.0	88.8
β-Conglycinin-rich	20.3	32.7	90.9	60.5
Total	34.1	56.4
aPurity expressed as % of storage protein present in said fraction

EXAMPLE 7

Another alternative new fractionation procedure of this embodiment is to produce a glycinin-rich flour and a β-conglycinin-rich supernatant by scalping the majority of the β-conglycinin while leaving the majority of the glycinin with the fiber residue. The starting material for this example was hexane-defatted and air-desolventized white flakes from soybeans. The flakes were milled to obtain a flour that passed through a #50 mesh. The protein content of said flour was 56.5%, the fat content 0.7% and the resulting flour had a PDI of 79.33 as determined by Silliker Laboratories.

All processes in this example had the same starting step, the flour was first added to de-ionized water at flour-to-water ratio of 1:10; the resulting slurry was stirred for 30 minutes without pH adjustment; then sufficient NaHSO₃ and CaCl₂ was added to obtain 10 mM concentration of each salt and the pH was adjusted to specific values described as follows:

• • Treatment #1 pH 6.4.
  • Treatment #2 pH 6.2.
  • Treatment #3 pH 6.0.
  • Treatment #4 pH 5.8.
  • Treatment #5 pH 5.6.
  • Treatment #6 pH 5.4.

The resulting flour slurry was stirred at 25° C., and after 1 hour the slurry was centrifuged at 14,000×g and 25° C. for 30 minutes to separate the glycinin-rich flour from the protein extract. The products of these processes were a glycinin-rich flour and a β-conglycinin-rich extract as described in FIG. 13. The resulting yields of solids and protein, protein contents and protein purities for protein fractions obtained are shown in Table 34.

TABLE 34
Fraction yields and compositions of alternative fractionation
when scalping β-conglycinin
	Solids	Protein	Protein
	Yield	Yield	Content	Puritya
Treatment/Fraction	(%)	(%)	(%)	(%)
Treatment #1
Glycinin-rich	52.0	57.0	61.4	68.6
β-Conglycinin-rich	48.0	43.0	50.6	70.0
Treatment #2
Glycinin-rich	54.2	61.9	64.0	67.5
β-Conglycinin-rich	45.8	38.1	47.0	71.5
Trearment #3
Glycinin-rich	57.8	68.0	65.9	66.8
β-Conglycinin-rich	42.2	32.0	42.8	72.5
Treatment #4
Glycinin-rich	59.6	68.2	64.1	65.9
β-Conglycinin-rich	40.4	31.8	44.5	74.5
Treatment #5
Glycinin-rich	64.5	79.9	69.4	60.1
β-Conglycinin-rich	35.5	20.1	32.0	84.0
Treatment #6
Glycinin-rich	67.2	80.0	66.7	61.5
β-Conglycinin-rich	32.8	20.0	34.5	86.1
aPurity expressed as % of storage protein present in said fraction.

As an alternative to the above treatments, the processes were repeated with the following changes. The flour was first added to de-ionized water at 1:10 flour-to-water ratio; sufficient alkali was added to obtain pH 8.5 and stirred for 30 minutes at 25° C.; after sufficient NaHSO₃ and CaCl₂ were added to obtain 10 mM concentrations of each salt and the pH adjusted to a specific value described as follows:

• • Treatment #7 pH 6.4.
  • Treatment #8 pH 6.2.
  • Treatment #9 pH 6.0.
  • Treatment #10 pH 5.8.
  • Treatment #11 pH 5.6.
  • Treatment #12 pH 5.4.

The resulting flour slurry was stirred at 25° C., and after 1 hour the slurry was centrifuged at 14,000×g and 25° C. for 30 minutes to separate the glycinin-rich flour from the protein extract. The products of these processes were a glycinin-rich and fiber-rich product and a p-conglycinin-rich extract as described in FIG. 13. The resulting yields of solids and protein, protein contents and protein purities for the protein fractions obtained are shown in Table 35.

TABLE 35
Fraction yields and compositions of alternative fractionation
when scalping β-conglycinin
	Solids Yield	Protein Yield	Protein	Puritya
Treatment/Fraction	(%)	(%)	Content (%)	(%)
Treatment #7
Glycinin-rich	49.5	53.2	60.1	65.4
β-Conglycinin-rich	50.5	46.8	52.4	60.7
Treatment #8
Glycinin-rich	53.9	61.5	63.7	64.8
β-Conglycinin-rich	46.1	38.5	47.2	62.0
Treatment #9
Glycinin-rich	55.5	64.1	64.4	63.5
β-Conglycinin-rich	44.5	35.9	45.6	63.4
Treatment #10
Glycinin-rich	60.8	68.2	62.7	59.1
β-Conglycinin-rich	39.2	31.8	45.8	72.1
Treatment #11
Glycinin-rich	64.3	75.3	65.4	58.5
β-Conglycinin-rich	35.7	24.7	39.1	74.3
Treatment #12
Glycinin-rich	67.6	77.7	64.2	54.4
β-nglycinin-rich	32.4	22.3	38.9	75.6
aPurity expressed as % of storage protein present in said fraction

EXAMPLE 8

The new fractionation procedure can use full-fat soyflour. The starting material for this example was dehulled full-fat soybeans. Soybeans were milled to obtain a flour that passed through a #50 mesh screen. The protein content of said flour was 42.6% and the fat content 24.5% on a dry weight basis.

The flour was extracted with de-ionized water at 1:10 flour-to-water ratio and the pH was adjusted to 9.0. The resulting slurry was stirred at 25° C., and after 1 hour the slurry was centrifuged at 14,000×g and 25° C. for 30 minutes to separate the spent flour from the protein extract. The resulting protein extract, yielded 61.3% of the protein originally present in the flour.

To the resulting extract sufficient NaHSO₃ and CaCl₂ was added to obtain concentrations of 5 mM of each salt in said extract and the pH of the resulting slurry was adjusted to 6.0 to obtain the glycinin-rich precipitate and stirred for 15 minutes. After this initial stirring, the slurry was placed overnight in a cold room at 4° C. The next day the slurry was stirred again and centrifuged at 14,000×g and 4° C. for 30 minutes to obtain a glycinin-rich precipitate and a β-conglycinin-rich supernatant. The supernatant was adjusted to pH 4.6 and centrifuged again under the same conditions, recovering a β-conglycinin-rich curd, and an extract that we termed whey.

The resulting glycinin-rich precipitate yielded 16.0% of the solids and 31.8% of the protein originally present in the starting flour. This fraction contained 84.7% of the protein of which 61.5% was glycinin expressed as percentage of total storage protein present in said fraction. The resulting β-conglycinin-rich precipitate yielded 6.5% of the solids and 14.1% of the protein originally present in the starting flour. This fraction contained 92.5% of the protein of which 75.8% was β-conglycinin expressed as percentage of total storage proteins present in said fraction.

Claims

1. A method for obtaining a β-conglycinin-rich isolated protein fraction and/or a glycinin-rich isolated protein fraction from a vegetable protein source comprising: Obtaining a defatted vegetable protein source; Extracting said source with a dilute alkali with a pH of approximately 7 to approximately 11 to form a mixture of the proteins present in said vegetable source; Obtaining a supernatant protein extract from said mixture, Subjecting said supernatant to fractional precipitation with a multi-valent cationic salt, and a reducing agent to form a slurry; Adjusting the pH of said slurry to a pH of approximately 7 to approximately 5 to obtain a precipitate which is enriched in glycinin and a supernatant which is enriched in β-conglycinin as compared to percentages of each protein in the original mixture.

2. The method of claim 1 wherein said multi-valent cationic salt is selected from one or more of the following calcium, magnesium, zinc, iron, and their mixtures.

3. The method of claim 1 wherein said multi-valent cationic salt is replaced with an multi-valent anionic salt such as ethylene diamine tetraacetic acid and/or its salts.

4. The method of claim 1 wherein said reducing agent is selected from the group consisting of one or more of the following: sodium bisulfite, sodium sulfite, sulfur dioxide, ascorbic acid, erythorbic acid, and L-cysteine.

5. The method of claim 1 wherein said reducing agents are added during the during the extraction step.

6. The method of claim 1 further comprising the step of adjusting the pH of said β-conglycinin-enriched supernatant to a pH of between about 4 and about 6 to obtain a β-conglycinin-rich precipitate and a supernatant that is rich in lipoxygenase and trypsin inhibitors.

7. A β-conglycinin-enriched protein extract provided by the method of claim 1.

8. An glycinin-enriched protein precipitate provided by the method of claim 1.

9. The method of claim 1 wherein said vegetable protein source is soybeans.

10. The methods of claims 1 further comprising the step of: Re-dissolving said glycinin-rich and/or β-conglycinin-rich precipitates, respectively, by neutralizing said precipitates with dilute alkali to obtain a neutralized β-conglycinin-rich protein slurry and/or a neutralized glycinin-rich slurry.

11. The method of claim 10 further comprising the step of: Membrane filtering said neutralized glycinin-rich protein slurry and/or said β-conglycinin-rich protein slurry to obtain a concentrated glycinin-rich protein slurry retentate and/or a concentrated β-conglycinin-rich protein slurry retentate and filtrates that are mainly composed of water and minerals.

12. The method of claim 11 further comprising the steps of: Thermal processing said neutralized glycinin-rich protein slurry and/or said β-conglycinin-rich protein slurry, homogenizing said slurries and/or drying said slurries to form a glycinin-rich soy protein isolate powder and/or a β-conglycinin-rich soy protein isolate powder.

13. The method of claim 12 wherein said thermal processing consists of jet cooking said neutralized protein slurry.

14. The method of claim 12 further comprising the step of: adding lecithin or other food-grade additives to form a glycinin-rich protein product and/or a β-conglycinin-rich protein product.

15. The method of claim 10 further comprising the step of hydrolyzing said slurries

16. The method of claim 1 wherein said soybean source is normal or naturally occurring soybean varieties.

17. The method of claim 1 wherein said soybean source are modified soybeans (eg. lipoxygenase-null, low-phytate, high-oleic, high-p-conglycinin, high-glycinin, high-cysteine, low-linoleic, etc) obtained through traditional breeding methods and/or genetic manipulation.

18. The method of claim 1 wherein said soybean source is High-sucrose/Low-stachyose soybeans.

19. The method of claim 1 wherein said defatted vegetable source is obtained through organic solvent or supercritical CO2 extraction of the fat from a soybean matrix.

20. The method of claim 1 wherein said partially defatted vegetable source is obtained through aqueous processing or enzyme-assisted aqueous processing.

21. The method of claim 1 wherein said partially defatted vegetable source is obtained through screw pressing and/or Gas-Supported Screw Pressing (GSSP) and/or other mechanically oil extraction method, such as extruding-expelling, that produces a partially defatted soybean source and further comprising the steps of Extracting said source with a dilute alkali of pH of about approximately 7 to approximately 11 to form a mixture of proteins present in said vegetable source. Obtaining a supernatant oil-rich “cream” fraction and a supernatant protein extract from said mixture. Subjecting said protein extract to fractional precipitation as described in claim 1.

22. The method of claim 21 further comprising the step of jet cooking or any other thermal processing said cream fraction and subsequently homogenizing and/or drying said cream to obtain a dried high-oil/high-protein product.

23. A product produced by the method of claim 21.

24. A method for obtaining a β-conglycinin-rich isolated protein fraction and/or a glycinin-rich isolated protein fraction from a vegetable protein source comprising: Obtaining a full-fat vegetable protein source; Extracting said source with a dilute alkali of pH of about approximately 7 to approximately 11 to form a mixture of proteins present in said vegetable source; Obtaining a supernatant protein extract from said mixture, Subjecting said supernatant to fractional precipitation with a multi-valent salt, and a reducing agent to form a slurry; Adjusting the pH of said slurry to a pH of approximately 7 to approximately 5 to obtain a precipitate, which is enriched in glycinin, and a supernatant, which is enriched in β-conglycinin, as compared to the percentages of each protein in the original mixture.

25. A method for obtaining a β-conglycinin-rich isolated protein fraction and a glycinin-rich and fiber-rich protein product from a soybean source comprising: Obtaining a soybean source; Extracting said source with dilute alkali or acid of pH of about 6 to approximately 10 to form a mixture of proteins present in said soybean source; Subjecting said mixture to fractional precipitation with a multi-valent salt and a reducing agent to form a slurry; Adjusting said slurry with dilute alkali or acid to a pH of approximately 5 to approximately 7 to obtain an insoluble residue, which is enriched in glycinin and fiber, and a supernatant, which is enriched in β-conglycinin as compared to the percentages of each protein in the original mixture.

26. The methods of claim 1, further comprising one or more of the following steps: Thermally processing said extract; Adding lecithin or other food-grade additives; Deodorizing said extract; Homogenizing said extract; Aspectically packaging said extract; Sterilizing said extract to obtain β-conglycinin-rich soy milk

27. A product produced by the method of claim 26.

28. The method of claim 26 further comprising the step of drying said β-conglycinin-rich soymilk to create a β-conglycinin-rich soymilk powder.

29. The product produced by the method of claim 28.

30. A glycinin-rich and fiber-rich soy protein product produced by the claim 25.

31. A method for producing fractionated soy protein isolates with enriched levels of isoflavones comprising: Obtaining a defatted vegetable protein source; Extracting said source with a dilute alkali of pH of about approximately 7 to approximately 11 to form a mixture of proteins present in said vegetable source; Obtaining a supernatant protein extract from said mixture, Subjecting said supernatant to fractional precipitation with a multi-valent salt, and a reducing agent to form a slurry; Adjusting the pH of said slurry to a pH of approximately 7 to approximately 5 to obtain a precipitate which is enriched in glycinin and a supernatant which is enriched in β-conglycinin as compared to percentage protein the original mixture.

32. A method to obtain fractionated soy protein isolates and/or products with enhanced functional properties compared to protein isolates prepared by methods with multiple fractionation steps.

33. A method to obtain fractionated soy protein isolates and/or products with enhanced, emulsification capacity compared to protein isolates and/or products prepared by methods with multiple fractionation steps.

34. A method to obtain fractionated soy protein isolates and/or products with enhanced foaming capacity compared to protein isolates and/or products prepared by methods with multiple fractionation steps.

35. A soy protein composition comprising a β-conglycinin content between about 50% and about 90% of the protein and a glycinin content between about 10% and about 50% of the protein, wherein the total isoflavone content in the composition is greater than 1.5 mg/g on a dry weight basis.

36. A soy protein composition comprising a glycinin content between about 50% and about 90% of the protein and a β-conglycinin content between about 10% and about 50% of the protein, wherein the total isoflavone content in the composition is greater than 1 mg/g on a dry weight basis.