Patent Application
20070275123
The present invention relates to the use of a modified starch to increase the dietary fiber content of processed food compositions, including extruded food compositions. By using certain modified starches, food compositions may be processed using harsh processing conditions while retaining substantial dietary fiber. Further, such modified starches provide dietary fiber without the negative effects on textural or organoleptic properties of the food products which are typically associated with the addition of other dietary fiber sources.
Starch, as used herein, is intended to include all starches, flours, grits and other starch containing materials derived from tubers, grain, legumes and seeds or any other native source, any of which may be suitable for use herein. A native starch as used herein, is one as it is found in nature. Also suitable are starches derived from a plant obtained by standard breeding techniques including crossbreeding, translocation, inversion, transformation or any other method of gene or chromosome engineering to include variations thereof which are typically referred to as genetically modified organisms (GMO). In addition, starch derived from a plant grown from artificial mutations and variations of the above generic composition, which may be produced by known standard methods of mutation breeding, are also suitable herein.
Typical sources for the starches are cereals, tubers, roots, legumes and fruits. The native source can be corn (maize), pea, potato, sweet potato, banana, barley, wheat, rice, oat, sago, amaranth, tapioca (cassava), arrowroot, canna, and sorghum as well as waxy or high amylose varieties thereof. As used herein, the term “waxy” or “low amylose” is intended to include a starch containing no more than about 10%, particularly no more than about 5%, most particularly no more than about 2%, by weight amylose. Also used herein, the term “high amylose” is intended to include a starch containing at least about 40%, particularly at least about 70%, most particularly at least about 80%, by weight amylose. The invention embodied within relates to all starches regardless of amylose content and is intended to include all starch sources, including those which are natural, genetically altered or obtained from hybrid breeding. In one embodiment, the starch is a high amylose starch.
The starch of this invention is modified using methods known in the art including dextrinization selected from the group consisting of acid/heat and alkali/heat dextrinization and/or chemical modification using reagents selected from the group consisting of propylene oxide/phosphorus oxychloride (PO/POCl3), propylene oxide/sodium trimetaphosphate (PO/STMP), propylene oxide/sodium trimetaphosphate/sodium tripolyphosphate (PO/STMP/STPP), adipic acetic anhydride (Ad/Ac), acid converted/propylene oxide (H+/PO), propylene oxide (PO), acetic anhydride (AA), butyric anhydride (BA), and propionic anhydride (PA), and succinic anhydride (SA). In one embodiment, the starch of this invention is modified using acid/heat dextrinization and/or chemical modification using reagents selected from the group consisting of propylene oxide/phosphorus oxychloride (PO/POCl3), adipic acetic anhydride (Ad/Ac), acid converted/propylene oxide (H+/PO), propylene oxide (PO), acetic anhydride (AA), butyric anhydride (BA), and propionic anhydride (PA), and succinic anhydride (SA). In another embodiment, the starch of this invention is modified using propylene oxide. Such modifications are known in the art and are described for example in Modified Starches: Properties and Uses, Ed. Wurzburg, CRC Press, Inc., Florida (1986). The amount of modification may be varied to get the desired properties while retaining substantial dietary fiber. Starches may be modified with other reagents to impact textural or functional properties other than the TDF enhancement.
The starches of this invention may be gelatinized before or after modification by using techniques known in the art. Such techniques include those disclosed for example in U.S. Pat. Nos. 4,465,702, 5,037,929, 5,131,953, and 5,149,799. Also see, Chapter XXII-“Production and Use of Pregelatinized Starch”, Starch: Chemistry and Technology, Vol. III-Industrial Aspects, R. L. Whistler and E. F. Paschall, Editors, Academic Press, New York 1967. Those skilled in the art understand which modifications should preferably be done in the granular or non-granular (gelatinized) state.
The starch may be purified by any method known in the art to remove starch off flavors, colors, or other undesirable components that are native to the starch or created during processing or to sanitize microbial contamination to ensure food safety. Suitable purification processes for treating starches are disclosed in the family of patents represented by EP 554 818 (Kasica et al.). Alkali washing techniques are also useful and described in the family of patents represented by U.S. Pat. No. 4,477,480 (Seidel) and U.S. Pat. No. 5,187,272 (Bertalan et al.). The starch may be purified by enzymatic removal of proteins. Reaction impurities and by-products may be removed by dialysis, filtration, centrifugation or any other method known in the art for isolating and concentrating starches.
The resultant starch is typically adjusted to the desired pH according to its intended end use. In general, the pH is adjusted to 3.0 to about 6.0. In one embodiment, the pH is adjusted to 3.5 to about 4.5, using techniques known in the art.
The starch may be recovered using methods known in the art, particularly by filtration or by drying, including spray drying, freeze drying, flash drying or air drying. In the alternative, the starch may be used in the liquid (aqueous) form.
The resultant starch is added to any food formulation prior to processing in any amount desired or effective to provide the desired dietary fiber content. The amount of dietary fiber added and used in any given food formulation may be determined to a great extent by the amount that can be tolerated from a functional standpoint. In other words, the amount of starch used generally may be up to what is acceptable in organoleptic evaluation of the food composition or can be physiologically tolerated by the consumer. In one embodiment, the starch of this invention is used in an amount of from about 1 to 50%, and in another embodiment from about 15 to 25% by weight of the food formulation.
In one embodiment, the resultant starch is substituted for at least part of the fiber of the conventional formulation. In another embodiment, the resultant starch is substituted for at least part of the starch of the conventional formulation. The starch may be added to the formulation in the same manner as any other starch, and in one embodiment is added by mixing the starch directly into the formulation and in another by adding it in the form of a solution or dispersion.
The formulation is then subject to harsh processing known in the art to produce a food product. Such processing includes, without limitation, extrusion, homogenization, pasteurization, ultra-high temperature (UHT) packaging, and canning. These processes may be conducted using any suitable equipment known in the art. In one embodiment, the food formulation is exposed to a temperature of greater than 100° C. and/or pressure greater than 1 atmosphere (101.325 kPa).
Extrusion of the food formulation may be conducted using any suitable equipment and medium to severe process parameters known in the art. Since a large number of combinations of process parameters exist, e.g., product moisture, screw design and speed, feed rate, barrel temperature, die design, formula and length/diameter (L/d) ratios, Specific Mechanical Energy (SME) and Product Temperature (PT) have been used in the art to describe the process parameter window of the extrusion. In one embodiment, the food formulation is exposed to an SME of at least 130 Wh/kg and a PT of at least 160° C., and in another embodiment to an SME of at least about 160 Wh/kg and a PT of at least 190° C. In another embodiment, the food formulation is exposed to an SME of no greater than 500 and a PT of no greater than 220° C.
Upon exposure to harsh processing conditions, the resultant food composition retains a total dietary fiber content of at least 70% (w/w) of the pre-processed dry blend formulation, in one embodiment at least 80%, in another at least 85%, and in yet another at least 95% (w/w) of the pre-processed dry blend formulation. The resultant processed food compositions include a variety of food products including, but not limited to, cookies, biscuits, cereals, snacks, pasta, puddings, yogurts, retorted products, e.g., sauces and condiments as well as animal food products and any other extruded or harshly processed products in which a higher fiber content is desired.
Further, the extruded composition comprising the modified starch may have improved organoleptic properties in that the bulk density is the same or may be decreased compared to the same composition made in the same way without a modified starch. Thus, the food composition may have a lighter, airier texture compared to food compositions high in other types of fiber. Alternatively stated, the starch may provide both a higher TDF value and functional benefits to the food item being created. In one embodiment, the bulk density of the composition comprising the modified starch is no greater than that without the modified starch and in another embodiment, the bulk density of the composition comprising the modified starch is at least 5% less than that without the modified starch.
The resultant food composition may be formulated to achieve the desired total dietary fiber content. In one embodiment, the composition is formulated to increase the total dietary fiber content by from 2 to 50%, in another embodiment 2 to 35%, in still another embodiment 3-15%, and in yet another embodiment by from 3 to 10% by weight compared to the same composition processed under the same conditions without the modified starch. In yet another embodiment, the composition is formulated such that the total dietary fiber content of the composition is at least 10% (w/w) greater in another at least 15% (w/w) greater, in still another at least 35% (w/w) greater, and in yet another at least 50% (w/w) greater, than the same composition processed under the same conditions without the modified starch.
The compositions made using the modified starches of this invention may be fed to (ingested by) any animal, in one embodiment to mammals and in another embodiment to humans. Such compositions may contribute to the health of the animal in the same or similar manner as other food compositions which contain dietary fiber and or resistant starch, including without limitation by attenuating the glycemic and insulinemic response, reducing plasma triglycerides and cholesterol, increasing short chain fatty acids, acting as a prebiotic to increase the proliferation and/or activity of probiotic bacteria such as lactobacillus and bifidobacteria, and increasing micronutrient absorption such as calcium.
The following examples are presented to further illustrate and explain the present invention and should not be taken as limiting in any regard. All percents used are on a weight/weight basis.
The following test procedures are used throughout the examples—
Dietary Fiber—Dietary Fiber is quantitatively measured by the Association of Analytical Chemists (AOAC) Method 2001.03 (“Determination of Total Dietary Fiber in Selected Foods Containing Resistant Maltodextrin by Enzymatic-Gravimetric Method and Liquid Chromatography: Collaborative Study”, D. T. Gordon & K. Okuma, J. AOAC, Vol. 85, pp. 435-444 (2002)).
The following products are used throughout the examples—
The following drying methodologies were used throughout the examples—
Spray Drying—Spray drying was performed on a Niro Spray Dryer with a two fluid nozzle. The starch was slurried at 20-30% (w/w) solids in water and was introduced directly into the nozzle with the feed rate of 3000-35000 psi. In the nozzle, the slurry was coming in contact with steam at 120-180 psi. Slurry solids, pumping rate, length of the nozzle, steam pressure, and back pressure in the nozzle were manipulated to accomplish desired degree of starch gelatinization.
Drum Drying—Starch was slurried at 35-40% solids and fed between rotating rollers. The rollers were rotating at 6-10 rpm and were heated by steam at 110-160 psig to 110-140° C. Sheet of the cooked starch was removed from the drum by a blade, ground and sieved to form final starch powder.
Coupled jet-cooking and spray-drying was performed as described in the patent U.S. Pat. No. 5,131,953. The process was performed at 20-30% solids and low steam pressure. The starch slurry was subjected to 80-90° C. cooking temperature. The steam pressures to the cooking chamber and line pressure to the spray drier were at 100 psi.
3,000 ml of tap water were measured into a reaction vessel. 100 g Na2SO4 were added with agitation and stirred until dissolved. With good agitation, 2,000 g of corn starch was added and then 3% NaOH was added drop-wise to the slurry as needed to reach 40 ml alkalinity (667 g NaOH for 44.00 ml alkalinity). The slurry was stirred 1 hr and the pH was recorded (pH 11.68). The temperature was adjusted to 42° C. 160 g of a 99/1 STMP/STP blend was added and allowed to react for 4 hours. The final pH and temperature were recorded (pH 11.02 and 42° C.). The pH was adjusted to 5.5 with 3:1 HCl (pH 5.47 using 164.99 g HCl). The resultant starch case was filtered and washed twice with 3,000 ml tap water. The cake was crumbled and air dried.
The starches were evaluated in expanded snack to examine their TDF retention in food application representing a process with severe heat and shear component. Expanded products similar to corn curls were selected as a severe extrusion model system since temperature and Specific Mechanical Energy (SME) during processing of puffs is relatively high.
The formula consisted of degermed corn flour and water. The experimental samples were used to replace 20% (w/w) of degermed corn flour and were compared to a control prepared with 100% degermed corn flour. The dry formula feed rate was 100 kg/hr, extruder shaft speed was 400 rpm, water flow to extruder was 5.5-6.0 kg/hr. The total moisture in extruder was 15.5-16%.
Dry materials were blended in the ribbon mixer, Wenger Manufacturing, Inc., model No. 61001-000 for 10 min, fed into a hoper and extruded without preconditioning. The feed rate was 100 kg/hr. For the 3 barrel extruder design used, the barrel temperature profile was set to 50° C., 80° C., and 92° C. and was maintained within four degree range. The SME was calculated according to a formula presented below to serve as an indicator of the mechanical shear input to the process—
TorqueActual/TorqueMax×Screw SpeedActual/Screw SpeedMax×Engine Power Constant/Throughput Rate
The SME range was 130-140 Wh/kg and the measured product temperature was 160-170° C. From the extruder, expanded samples were sent to a drier. Drier temperature was set in a first zone to 130° C., and in second and third zones to 30° C. Total retention time in the drier was approximately 8 minutes. At the exit of the drier, products were collected into lined boxes and packaged to minimize atmospheric moisture pick up.
TDF of the dry blends and final products was determined using AOAC 2001.03 method. TDF retention was calculated according to the formula—
TDF Retention (%)=(TDFExtrudate×100)/TDFDry Blend
Bulk density (DB) was measured by weighing (W) known volume (V) of cereals and calculating according to the formula DB=W/V and expressed in kg/m3
Modified food starch (Starch Sample 15) was tested in a pudding application, at 20% and 30% by weight in the finished pudding, to determine process tolerance compared to a control starch. Waxy maize (Starch Sample 1) is typically used in puddings and was utilized in the Control. The control was used at a relatively lower concentration at 6.75% due to viscosity limitations.
Puddings were prepared using a Vorwerk Thermomix Model TM 21. The Thermomix mimics processing conditions used for puddings by continuously mixing the batch, while keeping the temperature constant.
The above dry pre-mixes were prepared and slowly whisked into the pre-weighed amount of distilled water according to the pudding formulas below.
After the dry ingredients were hydrated, the pudding mixture (≈800 grams) was poured into the Thermomix. The temperature setting of the Thermomix was set to 200° F. (93.3° C.) and the shear setting was set to 1, which is the lowest. The timer was set to 35 minutes to take into account the 10 minutes required for the pudding mixture to reach 200° F. (93.3° C.) [come-up time], and the hold time of 25 minutes at 200° F. (93.3° C.). After 35 minutes of mixing, the finished pudding was poured immediately into plastic cups and placed in the refrigerator at 40° F. (4.4° C.).
The puddings were stored at 40° F. (4.4° C.) for 24 hours before further analysis. After 24 hours, the pudding samples were freeze-dried. In order to achieve greater uniformity of drying, the pudding samples were diluted to 12.5% solids with distilled water. The diluted samples were poured into round bottom flasks and flash frozen using a dry ice-acetone bath. The samples were freeze-dried overnight using a FTS Systems Flexi-Dry™ MP bench-top freeze drier Model# FD-3-85A-MP.
Total Dietary Fiber (TDF) content of starches, dry pre-mixes, and freeze-dried pudding samples were analyzed using AOAC method 2001.03. The results were expressed on a dry basis. TDF retention was calculated according to the formulas:
TDF retention (%)=(TDF pudding)×100)/TDF pre-mix (1)
Post-Processing Ingredient TDF=TDF starch×TDF retention/100 (2)
As can be seen from the above Table, the experimental puddings (A and B) not only contained substantially more total dietary fiber than the control puddings and retained the dietary fiber upon processing, but also had an actual increase in total dietary fiber.
