Patent Application
20080050486
As discussed marine animals and marine plants are the main sources of EPA and DHA. The use of fish oils or marine oils as a source of EPA and DHA are well known. Recently, a number of manufacturers have developed highly efficient processes for growing marine micro algae. These micro algae are a source for EPA and DHA at high yields and in a sustainable fashion. One source of micro algae derived EPA and DHA is Martek Biosciences Corporation, Columbia, Md., USA. A second source is Nutrinova Nutrition Specialties and Food Ingredients, DE. The EPA and DHA extracted from these sources are in the form of triglycerides. The omega-3 fatty acids can be provided as a free flowing powder or they can be supplied in the form of oils for the present invention. Typically the omega-3 fatty acids are encapsulated, a free flowing powder, or an oil mixture. One omega-3 fatty acid containing oil preparation is designated as HM by Martek Biosciences Corp. which has approximately 30 to 35% DHA. Martek also supplies a powder containing omega-3 fatty acids designated as Martek DHA™ powder KS35. In the present specification and claims either Martek source can be used as can the sources of other and unless specifically noted no distinction is made between the two forms.
Most attempts in the past to incorporate omega-3 fatty acids into foods have concentrated on developing methods that prevent the oxidation of the omega-3 fatty acid from occurring. As noted, these methods have met with limited success. Other efforts have focused on use of breathable packaging which allows the oxidation products to leave the food product thereby lowing their detection by consumers. Other efforts have been directed toward trying to determine what the oxidation products are and then identifying which ones cause the undesirable odors and tastes. Autoxidation of lipids in foods results in formation of a variety of aldehydes including saturated aldehydes, α,β-monounsaturated aldehydes, polyunsaturated aldehydes, and hydroxylated aldehydes. Several monounsaturated and polyunsaturated aldehydes have been identified as potentially being the fishy odor and taste causative agents in marine oils. These include cis-4-heptenal; 2,4-octadienal; and trans-2, cis-6-nonadienal. Other aldehydes that have been shown to arise during autoxidation of other long chain polyunsaturated fatty acids include cis-4-heptenal and octanal.
The present invention is directed toward a method for trapping the autoxidation products and thereby removing the rancid fishy aroma and taste in food products. This approach is different from those that have been used by others in the past. It was hypothesized that addition of proteins, protein fragments, partially hydrolyzed proteins, or amino acids in some manner to food products might be able to trap these aldehydes released from the food products and avoid the development of rancid or fishy aromas and tastes in foods having omega-3 fatty acids or other oxidatively unstable fatty acids and oils incorporated into them.
In a first test a series of cereals with different levels of protein were tested for their ability to quench or remove a series of aldehydes, three of which have been positively identified as generated by DHA and EPA autoxidation, spiked into the cereal at a known amount. The five test aldehydes chosen were: cis-4-heptenal, octanal, trans-2-octenal, 2,4-octadienal, and trans-2-cis-6-nonadienal. The cereals chosen were Special K® vanilla, Special K® Protein Plus, Smart Start® Antioxidant, Smart Start® Healthy Heart, and Corn Flakes®. The cereal products were ground using a coffee mill and one gram of each ground cereal product was weighed into a 20 milliliter headspace vial. The five test aldehydes and an internal standard ethyl heptanoate were each dissolved in heptane. Then each vial containing ground cereal was spiked with either 5 or 30 micrograms of each test aldehyde and the internal control. Each vial was capped and stored at room temperature for three days. At the end of incubation, the remaining headspace aldehydes were analyzed by headspace Gas Chromotography-Flame Ionization Detection (GC-FID). The results are shown in Table 1 below.
Several observations can be made concerning the data. First, the lowest protein cereal Corn Flakes® also had the highest residual headspace levels of all of the tested aldehydes at both spiked levels. Second, within a type of cereal, i.e. Special K® or Smart Start®, the higher the protein level the lower the residual headspace levels of all the tested aldehydes at both spiked levels. Finally, there may be other effects of the type of cereal since the residual headspace levels of all of the tested aldehydes, except for the 30 microgram spike of 2,4-octadienal, were lower in the Special K® vanilla than in the Smart Start® Healthy Heart despite the higher level of protein in the Smart Start® Healthy Heart. The data suggested that proteins may be useful in trapping or quenching the aldehydes produced by omega-3 fatty acids and other lipids in foods. Therefore additional tests were conducted to determine the effectiveness of protein in quenching these test aldehydes.
In the next series of experiments the ability of various proteins to quench the test aldehydes was examined. In each case one gram of the test material was added to a 20 milliliter headspace vial. Then each vial was spiked with 10 micrograms of each of the test aldehydes. After 1 hour at room temperature the aldehyde quenching index (AQI) was determined using GC-FID of the headspace as before. The AQI of a particular sample is calculated by normalizing the AQI of corn starch as 1 as a control, i.e., AQI=Aldehyde Quenching Capability (AQC) of sample/AQC of corn starch. The AQC is calculated using the formula below wherein: AIS is the peak area of the internal standard; WIS is the weight of the spiked internal standard in micrograms; AA is the peak area of the spiked aldehyde compound; and WA is the weight of the spiked aldehyde compound in micrograms. In these experiments corn starch, which does not quench any of the test aldehydes, was used as a control internal standard and its AQI was set to 1. The larger the AQI the greater the quenching effect. In the table whey protein isolate is abbreviated (WPI). The results are presented in Table 2 below.
The results show that the whey protein isolate (WPI) and soy protein were very effective at quenching the aldehydes compared to corn starch, gluten, dextrose, dextrin, and maltodextrin. In the next series of experiments the dose dependency of the effect of whey protein isolate and soy protein was determined. Each protein was mixed with dextrose at a series of ratios and the AQI of each blend was determined after 16 hours at room temperature. Again each 20 milliliter headspace vial included 1 gram of the dextrose/protein blend and was spiked with 10 micrograms of each of the test aldehydes. Headspace aldehyde was determined as before using GC-FID. The results are presented in Tables 3 and 4 below.
The results show a clear relationship between the level of either WPI or soy protein and the ability to quench the test aldehydes. In addition, one can see differences in the quenching of a given test aldehyde depending on the protein source. It may be that a combination of proteins is best in quenching all of the aldehydes.
In the next series of experiments the effect of hydrolysis of the WPI or soy protein on quenching ability was determined. The degree of hydrolysis of a sample was determined using the following formula: Degree of Hydrolysis=(amino nitrogen in the sample/total nitrogen in the sample)*100. The experimental design was as in previous experiments, however, the samples were incubated at room temperature for 4 hours. The results are shown in Table 5 below. The results indicate that enhanced quenching can be achieved by using partially hydrolyzed proteins compared to the native proteins themselves.
Based on the results in Table 5 the next series of experiments were designed to determine the effect of the degree of hydrolysis of a WPI on its ability to quench the test aldehydes. The testing protocol was as described in Table 5 using various WPI that were partially hydrolyzed to different degrees. The figure clearly shows that as the degree of hydrolysis increases the quenching ability also increases; however, it is also known that as the degree of hydrolysis increases so does the bitterness flavor of the partially hydrolyzed WPI. Therefore, there may be an organoleptic limit to the degree of hydrolysis that is useful. The results are presented in
In another series of tests the effect of water activity of the partially hydrolyzed WPI sample on its ability to quench the test aldehydes was determined. For this experiment the WPI had a degree of hydrolysis of 26 as calculated above and the water activity varied from 0.07 to 0.466. The results are shown in
In another series of experiments the ability of various amino acids to quench the test aldehydes was determined. The process was as described above in Table 5. The results are presented below in Table 6. A reading of below the detection limit (bdl) means that no aldyhydes were detectable, i.e. quenching was essentially complete. One can see that there are vast differences between the various amino acids in their ability to quench. Some are no better than corn starch and others are excellent quenchers.
The amino acids L-Lysine, L-cysteine, β-alanine, L-Arginine, L-cysteine ethyl ester HCl, and γ-amino butyric acid are the most effect in quenching the test aldehydic compounds. The AQIs of these amino acids are substantially higher than protein and partially hydrolyzed proteins. Among these most effect amino acids, there is a common functional structure, i.e. the amino group is not in the α position of the amino acid. In other words, the most effective amino acids in quenching the test aldehydic compounds are those with the amino group in the β or farther position of the carbon chain from the carboxylic acid group of the same molecule or they have a sulfhydryl group like cysteine.
In all the experiments described above the quenching effects were also tested by sniffing the products at the end of the incubations. Those with significant quenching were less odiferous and in some there was not detectable odor. The results demonstrate that the quenching can be accomplished in prepared foods by adding protein, partially hydrolyzed protein, or amino acids to the foods. The present invention can be used to quench the rancid or fishy odors and tastes found in foods containing long chain polyunsaturated fatty acids such as linoleic acid, linolenic acid, docosahexaenoic acid, eicosapentaenoic acid, and the oils discussed above. The quenching can occur in the interspatial headspace in the food and in the headspace of the food packages. The quenching effect can be demonstrated in low, intermediate and high moisture food products. The quenching effect occurs at ambient temperature.
It is hypothesized that the reaction between the aldehyde and the amino acids, be they in a peptide or not, may occur via a Michael-type addition or through a Schiff base reaction. The invention can be used in a large variety of ways. The amino acid source can be a protein, partially hydrolyzed protein, modified protein, or selected amino acids. In one method, the amino acid source can be used to encapsulate the oxidatively unstable oils and fatty acids. As discussed above typical unstable oils/fatty acids include soybean oil, flaxseed oil, marine oil, marine micro algae oil, linoleic acid, linolenic acid, docosahexaenoic acid, and eicosapentaenoic acid. The encapsulation could be accomplished by simple blending of the oil or DHA source with the amino acid source in water followed by drying in a spray dryer or fluidized bed dryer. Alternatively, the amino acid source and the DHA source can simply be blended together. Use of a powdered DHA source makes for very easy blending with the amino acid source. The source of amino acids could be, for example, albumin, whey protein, whey protein isolate, soy protein, partially hydrolyzed proteins, amino acids, or other proteins or partially hydrolyzed proteins. The level of amino acid source can be varied depending on what is necessary to maintain the quenching for the desired period of storage time. The encapsulated oil can then be added to food products with the expectation that the food will remain stable, i.e. no rancid or fishy aromas or tastes, with respect to the oxidatively unstable fatty acids over a significant storage period. In another method, the amino acid source could be provided in a sachet and the sachet could be placed, for example, into a package of the food such as a box of ready to eat cereal. In another use the amino acid source could be incorporated onto or into a bag liner or packaging material. It is believed that all of these methods will work to extend the shelf life of food products that contain oxidatively unstable oils or fatty acids.
The teachings from the above experiments were applied to a first food example by using the insights to test the ability of a series of protein combinations that included varying amounts of partially hydrolyzed and non-hydrolyzed protein from a variety of sources to prevent development of fishy aroma in cold formed cereal bars that included the omega-3 fatty acid DHA. Both oil and powdered sources of DHA were tested in the protocol. The formula for the chocolate flavored cold formed cereal bar is given in Table 7 below. The protein sources were as follows: Barflex is a partially hydrolyzed whey protein, Provon 190 is a non-hydrolyzed whey protein, Solae 313 is a partially hydrolyzed soy protein, Solae 661 is a non-hydrolyzed soy protein. The source of DHA was either Martek's powder KS35 or the oil HM. A series of twenty conditions were created as noted in Table 8 below. All of the bars included 100 milligrams of DHA per serving, this required from 1 to 4% by weight of the DHA source and adjustments in the amount of the other components were made to accommodate this. After formation the cold formed bars were packaged and stored at 85° C. 50% relative humidity. Samples of each condition were evaluated for development of fishy aroma or taste by trained organoleptic specialists at time 0 and on a weekly basis thereafter over a 12 week period. Each sample was given a ranking of from 1 to 5, with 5 being the highest level of fishy aroma or taste. The bars were formed as follows the oil blend and the dry blend were combined. The mixture was then bound together using the binder syrup and cold formed into a mass that was cut into bars. All steps were performed at temperatures of 115° F. or less. The cold forming can be accomplished as known in the art by extrusion, compression rolling or other methods of cold forming. Cold forming refers to a process wherein external heat is not added to the forming system. The cold formed bars were then enrobed in a compound coating and packaged. The results of the analysis are given in Table 9 below. Each result is the average of at least 4 evaluations at each time point.
The results were quite dramatic with the Barflex, partially hydrolyzed whey protein, being far superior to the Solae 313, partially hydrolyzed soy protein, in virtually all cases. Almost all conditions that included partially hydrolyzed whey protein, even at the lowest level of 20% of total protein, stayed at a ranking of 1 or less for the entire test period. The samples with Barflex and Provon 190 are numbers 1, 5, 8, 15, and 16. The samples with Barflex and Solae 661 are numbers 3, 7, 12, 17, and 19. By way of contrast, many of the partially hydrolyzed soy protein samples achieved rankings of 3 to 5 that occurred early on and were maintained. The samples with Solae 313 and Provon 190 are numbers 6, 11, 13, 14, and 18. The samples with Solae 313 and Solae 661 are numbers 2, 4, 9, 10, and 20. The results clearly show the benefit of inclusion of the partially hydrolyzed whey protein in maintaining the stability of actual food samples that included DHA and show that this effect can be achieved with as little as 3.6% partially hydrolyzed whey protein in the final food product.
In another food product example the DHA source HM, was combined with partially hydrolyzed whey protein at a weight ratio of 25% HM with 75% partially hydrolyzed whey protein. The partially hydrolyzed whey protein was in a water solution at a ratio of 1 part partially hydrolyzed whey protein to 20 parts water. The HM and partially hydrolyzed whey protein solution were homogenized together and then spray dried to form a powder. This powder was then incorporated into a variety of food types.
In a final food example the spray dried DHA and protein powder described above was used in a formulation for preparing a baked fruit filled bar product. The basic processing steps were as follows: formation of the dough; formation of the fruit-based filling material; co-extrusion of the filling material and the dough layer at a low temperature of less than about 130° F. with cutting to length, the dough surrounding the fruit based filling; and baking the bars at approximately 390° F. for 8 minutes; cooling the bars and packaging them. The bars were baked to have a final water activity of 0.7 or less. The fruit based filling is a typical fruit based filling as is know in the industry. The filling typically comprises: high fructose corn syrup, corn syrup, fruit puree concentrate, glycerin, sugar, modified corn starch, sodium citrate, citric acid, sodium alginate, natural and artificial flavors, dicalcium phosphate, modified cellulose, colorings, and malic acid. Any known filling material can be used in the invention. The stability of the omega-3 fatty acids is not altered by the filling composition in this invention. Generally the finished bar comprises from 55 to 65% by weight dough with the remainder being filling. The fruit filled bar products included sufficient DHA source to produce 40 milligrams of DHA per serving. The formulas for the bars with and without the DHA protein powder are given in table 10 below. The control, sample 1, was addition of DHA to the dough without the amino acid source. Sample 2 included DHA and the partially hydrolyzed whey protein powder described above. The products were stored at under several conditions. In a first condition the bars were stored at 85° F. 50% relative humidity and tested weekly for development of fishy aroma or taste. Under this condition the control bars with DHA in the absence of protein began to fail at 6 weeks and all failed by 9 weeks. They all developed fishy aromas and tastes. By way of contrast, none of the samples made with the DHA protein powder developed a fishy aroma or taste under this condition for over 12 weeks. In another test the samples were stored at 70° F. 50% relative humidity and tested periodically for development of fishy aroma or taste. The control samples failed within 9 weeks while the samples made with DHA and protein were stable for at least 6 months.
The discoveries of the present invention have wide application to a variety of food products. The results demonstrate that combining an amino acid source with sources of DHA or EPA stabilizes the DHA and EPA and prevents the development of fishy aromas and tastes over extended storage times. The amino acid source preferably comprises at least one partially hydrolyzed whey protein or free amino acids. The stabilization can be achieved either by initially combining the amino acid source with the DHA or EPA source or by including an amino acid source in a food product containing a DHA or EPA source. This invention is applicable to a wide range of food products including ready to eat cereals, potato chips, nacho chips, corn chips, crackers, cookies, toaster pastries, fruit filled bars, granola bar, cereal bars, baked cheese curls, fried cheese curls and other food products. It is preferable that if the amino acid source is initially combined with the source of DHA or EPA that the weight ratio be 1 part DHA and/or EPA to 0.1 to 50 parts amino acid source, preferably partially hydrolyzed whey protein or other partially hydrolyzed proteins. In a food product preferably a 100 gram serving includes from 10 to 2000 milligrams of DHA and/or EPA and 100 milligrams to 40 grams of an amino acid source. As described above preferably the amino acid source comprises partially hydrolyzed whey protein or other partially hydrolyzed proteins. It is believed that similar ratios of protein to autoxidation prone lipid are applicable to lipids other than DHA and EPA.
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of the invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.
This application claims the benefit of U.S. provisional application 60/823,322 filed Aug. 23, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60823322 | Aug 2006 | US |
