Soy-Based Nutritional Beverages - ACS Symposium Series (ACS

Chapter 20

Soy-Based Nutritional Beverages

Downloaded by STANFORD UNIV GREEN LIBR on July 27, 2012 | http://pubs.acs.org Publication Date: December 1, 2003 | doi: 10.1021/bk-2004-0871.ch020

Jimbin Mai and Grace S. Lo DuPont Protein Technologies, 824 Gratiot Street, St. Louis,MO63102

The FDA's approval of the health claim for soy protein has triggered tremendous interest in developing soy-based products. Of these, ready-to-drink nutritional beverages are of most interest. In the course of developing nutritional beverages, several criteria need to be considered. These are target market segments, consumer age group, special nutritional requirements, shelf life requirement for the distribution, nutritional profile of macronutients, vitamin and mineral supplements and finally, packaging and processing methods. In this overview, discussion will be focused on the design of nutritional beverages targeting different consumer groups. These beverages are designed for general well being, balanced nutrition, generation Y (the thirties), generation X (the forties), the baby boomers, weight loss and meal replacement, geriatric and medical nutrition. Given the merging trend of nutraceutical with the mainstream foods, soy is the prime choice of ingredient. Along with other nutraceuticals, soy protein based products will soon move to center stage for consumer foods. Compatibility and interaction of these ingredients and the effects of processing are also discussed.

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© 2004 American Chemical Society In Nutraceutical Beverages; Shahidi, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2003.


267 The FDA's approval of the soy health claim (/) has stirred considerable research and product development activities around the world. With advanced food technology and processing techniques, various protein products allow manufacturers to develop foods that offer excellent taste, texture, mouthfeel, flavor and eating quality with distinct nutritional and health benefits. Soybeans have 42% protein, 20% fat, 20% carbohydrate, 5% hull and 13% ash and water. After oil extraction and desolventization, defatted soy flour has 50% protein. By further refining to remove more carbohydrates 70% protein soy flour is obtained (soy concentrate). After more elaborate processing, a product with >90% protein on a dry weight basis known as soy protein isolate is produced (isolated soy protein). Protein Quality Not all proteins are created with equal nutritional values. For Supro® isolated soy proteins (DuPont Protein Technologies, St. Louis, MO), a tremendous amount of research effort has been devoted to understanding the effect of processing on the product quality and also on its effects on nutritional value and protein utilization. Each soy protein product is specifically designed and manufactured to meet a particular application requirement. During the last three decades, we have studied the protein quality and food applications for human consumption, heart disease, cancer, women health, sport nutrition, diabetes and weight management. Traditionally, protein efficiency ratio (PER) has been used as the standard measure of protein quality. A protein with PER of 2.5, using casein as the reference protein, is considered a complete protein (2). However, with the advanced research and understanding of biochemical science and nutrition, we learned that sulfur-containing essential amino acids are interconvertible and the human body has unique mechanism in conserving and recycling these sulfur-containing amino acids. Further, PER was established based on rat studies. In comparison to rat, human have much less hair and thus much lower requirements for sulfur-containing amino acids (3). Therefore, the current accepted method for evaluating protein quality by the United States Food and Drug Administration (FDA) is the Protein Digestibility Corrected Amino Acid Score (PDCAAS). The PDCAAS takes into account the food protein's essential amino acid content, its digestibility, and its relevance to human needs. The highest possible score of PDCAAS is 1.00. In Table I, the PDCAAS scores from various food protein sources are presented (2). As demonstrated in the table, ISP has a PDCAAS score of 1.00, comparable to the quality of meat, milk and egg proteins. The amino acid requirement pattern of the needs of a 2 to 5 year old child, 10-12 year old child and an adult is shown in Figure 1, which represents the most demanding amino acid requirements of any group, except infants. As shown in the darkened histograms, Supro® brand isolated soy proteins meet the requirements of all the three age groups.

In Nutraceutical Beverages; Shahidi, F., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2003.


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Table I. Protein Digestibility Corrected Amino Acid Scores PDCAAS Product 1.00 SUPRO® Isolated Soy Protein 1.00 Casein 1.00 Egg White 1.00 Skim Milk Powder 1.00 Whey Protein Concentrate 0.92 Beef Protein 0.69 Pea Flour 0.68 Kidney Beans (Canned) 0.63 Pinto Beans (Canned) 0.40 Whole Wheat 0.25 Wheat Gluten

^1

"HIS—ICE—LEU

SUPROIsolated Soy Protein

LVS MET+PHE + THH—ÎRY VAL CYS TYR

* Sug gested Pattern of Req uirerants(FAO/WHO/UNU, 1985).

Figure 1. FAO/WHO/UNUEssential Amino Acid Requirement Patterns (Reproduced from reference 4. Copyright 1985.)


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Calcium Bio-availability

One of the major concerns of using soy protein in a milk type nutritional beverage is that the calcium content of soy is relatively low and exogenous sources of calcium are required to bring up the calcium level. When supplementing calcium, the two major challenges are the bioavailability and the homogeneous suspension of calcium in the finished beverage. The results from an animal feeding study indicate that the calcium is biologically available from calcium fortified soy beverages and calcium neutralized ISP is equal to the calcium avalable from calcium carbonate and nonfat dry milk (Table II).

Table IL Calcium Bio-availability using rat as experimental model Relative Bioavailability, % Serum Calcium Bone Calcium Calcium Carbonate 100 100 Di-Calcium Phosphate 100-112 95 -109 Tri-Calcium Phosphate 94 -106 91 - 107 Calcium Oxide 90-105 97-110 Skim Milk Powder 108 - 124 UHT Ca-Fortified Soy Beverage 97-113 Isolated Soy Protein + Whey 99-114 Ca-Neutralized ISP 103-119 Source: Adaptedfromreference 5.

Both calcium fortified soy beverages and neutralized ISP, showed excellent calcium bioavailability. To ensure that all the fortified calcium in beverages are available to the consumer, it is necessary to suspend homogeneously all the beverage calcium. Through DuPont Protein Technoliges's (referred as "DPT") patented technology (US Patent 4,642,238), calcium in the soy beverages is much better suspended. With this patented technology, more than 70% of the added calcium was suspended throughout the shelf life of beverages, only 2040% suspension of calcium was achieved using the conventional gum technologies (8). The ISP's with stable calcium technology are called Supro Plus® ISP (DuPont Protein Technologies, St. Louis, MO). The bioavailability of calcium from Supro Plus® protein was equal to that supplemented calcium salts (Table III) (6). Thus, the bioavailability of calcium in Supro Plus® ISP is as good as commercial sources of calcium and cow's milk (5).


270 Table III. Calcium Bio-availability of Isolated Soy Based Diet Ca Salt SUPRO Plus Unit None Calcium Source 783 646 mg/wk 28.5 Calcium Intake 0.31 0.34 0.04 Bone Mineral g 0.23 0.22 0.07 g/cm Bone Density 12.60 11.20 mg/ml 7.9 Serum Ca 135 129 235 Serum PTH pmoles/L Source: Adaptedfromreference 6. Downloaded by STANFORD UNIV GREEN LIBR on July 27, 2012 | http://pubs.acs.org Publication Date: December 1, 2003 | doi: 10.1021/bk-2004-0871.ch020

2

Soy Ingredients for Product Development Twenty-five grams of soy protein a day reduces the risk of coronary heart disease. There are a series of bioactive compounds in soy, namely globulin, peptides, amino acids, phytic acid, saponins, isoflavones and protease inhibitors. No wonder that Prepared Foods (8) elected soy proteins, along with the other eight ingredients (Figure 2), as the top choice of ingredients by food product developers.

Figure 2. Top Ranking Ingredients (Reproduced with permission from reference 8. Copyright 2000.)


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Beverage Applications When using ISP in the development of nutritional beverages, the most important part of the application is dispersion and hydration of proteins. Only when the protein is properly dispersed and hydrated, can the expected functionality be expressed to create a stable and palatable beverage.


Dispersion and Hydration A well-dispersed and hydrated protein solution with a homogeneous phase is the first requirement for formulating good tasting and stable ready-to-drink (RTD) beverages. Isolated soy protein powder needs to be dispersed into individual particles in the processing water without any lumps. Lumps may be present if product is not properly dispersed. Time, temperature, shear energy, pH and ionic environment are the five factors affecting hydration of soy proteins. At constant temperature, prolonged hydration time results in a good protein hydration. When temperature is increased tol80°F, proper hydration is reached at a relatively shorter mixing time, say, 15 min. Higher shear energy facilitates hydration. However, care should be taken not to incorporate too much air into the protein slurry. Entrapped air in the beverage solution impedes the homogenization efficiency. At around pH 4.5, the isoelectric point of soy protein, ISP is least soluble (Figure 3). At pH's distant from the isoelectric point, improved protein hydration can be obtained. For organoleptic and functional reasons, pH range from 6.8 to 7.2 is most desirable for a low acid nutritional beverage.

1.0

20

3.0

40

5.0

&0

7.0

&0

PH * NitrogenSdubliV tidec.

Figure 3. Solubility* of Isolated Soy Protein as A Function ofpH


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High ionic strength also reduces the solubility of protein.. The solubility of the protein drops to 60% when the ionic strength of sodium chloride reaches 0.1M. Further increases in ionic strength increases the solubility. Somewhat presumably due to the charge effect. Divalent ions such as calcium, magnesium and zinc link to the negatively charged carboxyl ends of the protein and thus cause proteins to aggregate (Figure 4). However, a nutritional beverage requires the fortification of all three divalent ions. Chelating agents such as citrates and phosphates are required to make these ions unavailable to interact with proteins.

++

Ca

Figure 4. Divalent Ions Promote Protein Aggregation

An experiment was conducted (P) to determine the required amounts of either citrate or sodium hexametaphosphate to chelate a known concentration of calcium or magnesium, it was found that sodium hexametaphosphate was a more powerful chelating agent than citrate. For citrate, almost a one-to-one ratio of concentration of sodium citrate to calcium ion is required to chelate the free calcium. For sodium hexametaphosphate against magnesium ion, this ratio was only about 0.16.



273 Gum stabilizers are also commonly used to help suspend the protein and minerals in beverage. These gums are carrageenan, colloidal microcrystalline cellulose gel, cellulose gum, pectins and sodium alginates. Gums help build intermolecular bonding through electrostatic linkage, creating interstitial matrix making the protein movement in the fluid less freely or just by increasing the viscosity of the beverage to slow down gravity movement. In summary, to achieve a good hydration and thus a good functionality of protein in the finished beverage, we recommend that a soft water (total hardness less than 40 ppm expressed as calcium carbonate) or even de-ionized water be used. First dissolve the entire buffer salts completely before adding proteins. When adding proteins, raise the water temperature to 120°F with the mixing speed set at high. For production practice, a powder-dispersing device such as Tri-blender or Likwifier is highly recommended to use. These type of devices provide vigorous mixing and re-circulation of the dispersing fluid back to the high-shear-dispersing pump, which results in a lumpfreeprotein dispersion. The stabilizers, due to their minute quantities, can either be added before or after protein hydration. Since the quantities of the stabilizers are usually very small, an equal amount of sugar can be used to make a pre-blend to help with dispersing. Once protein and stabilizers are dispersed properly, the solution should be allowed to continue mixing at medium speed for 15 min. Medium speed used is to minimize any unnecessary incorporation of air, which, if not removed, may decrease the homogenization efficiency. Protein Selection When developing a soy based nutritional beverage, several considerations such as flavor and mouthfeel, suspension and emulsion stability, nutritional and health benefits, viscosity, color, mineral and vitamin fortification and micro biological purity all need to be considered depending on the development criteria required. A few examples demonstrating these criteria are presented below. When carbohydrates are used together with proteins, the choices of proteins and types of carbohydrates determine the final color of the finished beverages. In Figure 5, the upper row is the combination of caseinate with maltodextrin and corn syrup solids with various degrees of dextrose equivalent (DE). The lower row is the counterpart of caseinate using Supro Plus® 651 (an ISP protein product with suspendable calcium in the protein matrix supplied by DPT). It is clearly demonstrated that soy protein has fewer interactions in the browning reaction and thus much whiter finished beverages result. The viscosity has influence on the stability of the emulsion, the mouthfeel of the finished beverages, and the flowability of the beverage through the tube feeding. Depending on the protein content of the finished beverages, proteins with different viscosity can be chosen for the purpose. At lower protein content, i.e., < 6.25g protein/8oz serving, proteins with slightly higher viscosity should be used to provide better mouthfeel and creaminess. While for balanced nutritional beverages, i.e., >_12.5g/8oz serving, a lower viscosity protein should be used.



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Figure 5. Maillard Reaction ofSodium Caseinate or Supro Plus® 651 with Different Carbohydrates (Reproduced with permission from reference 9. Copyright 2001.)


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Emulsifying properties of soy protein are very important for a stable beverage emulsion. For a high energy beverage and nursing home feeding program, as high as 2.0 Kcal/mL of beverage are quite common to provide between 360 to 480 Kcal per 8oz serving of beverage. Other than carbohydrates and proteins, the major cost-effective energy source is fats and oils. In Figure 6, the oil emulsion capacity of six different Supro® proteins are presented. The oil holding capacity is defined as the milliliters of oil can be held by one gram of protein in a defined concentration.

(rrtfg)

SUPRDA SUPROB SUPRDC SUPROD SUPROE SUPRDF Figure 6 Emulsion Capacity of Various Types of Supro® Proteins To meet different product development needs, DPT has Supro® proteins with PDCAAS scores of 1, Surpo Plus® proteins with stable calcium, Supro XT® proteins with improved flavor, dispersibility, managed minerals and controlled viscosity and SuproSoy with a certified level of total isoflavone at 3.4mg/g protein. Sharing the product development needs with the ingredient supplies is the key to a quick turn around for timly commercial success. Trust needs to be built up between the manufacturer and the supplier to achieve such a relationship. Considerations for Beverage Development In the process of developing successful commercial nutritional products, it is important to consider the nutrition profiles, the economy, the functionality and the health benefits. For nutritional consideration, we can divide it into macronutrients and micronutrients. For macronutrients, we consider calorie, fat,



276 carbohydrate & sweeteners. For micronutrients, we refer them to vitamin/mineral premix. The forms of the minerals do have significant impact on the color, flavor and taste of the finished beverages. For vitamins such as vitamin C, a significant level of overage should be built into the formulation to deliver the claimed values. This is a very specialized area and we recommend working with vitamin/mineral suppliers and communicate to them your processing conditions to ensure a reliable delivery of micronutrients For health oriented beverages, often, certain nutraceuticals are required to address certain market segments. This in general adds complication to the beverage system. For example, eicosapentaenoic acid (EPA) & docosahexaenic acid (DHA) in fish oil and conjugated linoleic acid (CLA) are very unsaturated and are thus very prone to oxidation. The oxidative decomposition products from these oils are notorious in odors and once developed are almost impossible to remove them completely. Green tea extracts and other polyphenolics of plant origins have an inherent property of precipitating proteins and add to the beverage instability. In the presence of ferrous or ferric ions, tea polyphenols react with iron to cause discoloration. For economic reason, one needs to consider the quality, application target, and consistent supply. Only all the requirements are fulfilled can the economy be considered. The health benefits of soy, the versatility of different soy ingredients for product development and in view of the recent rise in dairy prices, it justifies the consideration of this versatile ingredient. For commercial development, next to considered are the target market segment, ingredients decoration and labeling requirement (whether natural is required), package requirement, and the processing facilities. Finally and most importantly, the target date for commercial launch. Every activity caters to this date set. Criteria for A Good Tasting Products As reported by Tiax, LLC (11), successful food products in the market generally possess the following criteria: early impact of appropriate flavors, pleasant mouth sensation, full body of highly blended flavors, rapid disappearance offlavorson swallowing and absent of unpleasant aftertastes. In an attempt to achieve all these criteria, we examined the flavor attributes associated with a soyobased products as given below.

Characteristic Flavors Associated with Soy Beany, cereal-like, astringency, harsh, mouth drying and throat catching, slightly bitter if the soy protein is partially hydrolyzed, strong bitter and savory


277 notes when highly hydrolyzed, and grassy and green mainly due to lipid oxidation are the most commonly described soy flavor attributes. To remove or suppress all these undesirable flavors, flavor houses are working with different varieties of masking agents. An ideal masking agent is the one that can mask the undesirable flavor without producing any flavor characters of its own. A universal one-for-all masking agent is still die challenge for flavor houses as well as product developers.


Flavors Compatible with Soy Numerous goodflavoredsoy beverages have been introduced to the market with favorable response. It is our experience that certain flavors work better with soy than others. These flavors either deliver a brown note or go relatively well with soy. For brown flavors, we recommend hazelnut, English toffee, coffee latte, chocolate, caramel, rum raisin, and malt. Other flavors such as cream, almond, passion fruit, peach, apple, cereal, coconut, banana and honeydew melon and cantaloupe also go very well with soy-based beverages.

Summary With some care and following of the basic rules recommended above, good tasting soy-based nutritional beverages can be successfully developed. The flavor development work involves the covering or masking of the undesirable soy notes, conducting a high and low UHT production with the target flavor system, allowing for neuttal beverages 10 to 14 days holding period after UHT processing, tasting and adjusting the flavor to a desirable level, and confirming the selected dosage with repeated UHT productions. Over flavoring should be avoided due to the disproportional concentration of certain chemical components rendering the product with a strong chemical taste which would be unacceptable. As a rule of thumb, a mix flavor is always better than a single flavor.

Acknowledgement The authors would like to take this opportunity to thank Ms. Patsy King and Ms. Katherine Reinecke for their skilled editing efforts on the text and Dr. Xiaolin Huang for use of some of his data and pictures.

References 1.

St. Louis Post-Dispatch, Tuesday Oct. 21, 1999, Vol: 121, No 294, 1999.


278 2.

3. 4.


5. 6. 7. 8. 9. 10. 11.

Protein quality evaluation Report of Joint FAO/WHO Expert Consultation, FAO Food and Nutrition Paper 51, Food and Agriculture Organization of the United Nations, Rome, 1991. National Research Counsel, Nutrient Requirements for Laboratory Animals. No. 10. National Academy of Sciences, Washington, DC, 1978. Joint FAO/WHO/UNU Expert Consultation. Energy & Protein Requirements. WHO Tech. Rept. Ser. No 724. World Health Organization, Geneva, Switzerland, 1985. Lo, G.S.; Lin, S. H. C.; Steinke, F. H. Fed. Proc., 1987, 46, 888. Venkataraman, P.S.; Hinahon, E.; Boyle, E.; Lien, E. Ped. Res., 1992, 31(4), 297A. Cho, M.; Lin, S. DuPont Protein Technolgoies internal communication, St. Louis, MO 63102, USA, 2001. Prepared Food, Nov., 2000. Huang, X. DuPont Protein Technolgoies internal communication, St. Louis, MO 63102, USA, 2001. Courtesy of Dr. Xiaolin Huang, DuPont Protein Technoglies St. MO 63102, USA, 2001. Soyatech and Arthur D. Little, e-Sensory perceptions, Sensory Benchmarking: The U.S. Soymilk Market 2001. Soyatech, 7 Pleasant St., Bar Harbor, M E 04609, Arthur D. Little, 15 Acorn Park, Cambridge, M A 02140.


Soy-Based Nutritional Beverages - ACS Symposium Series (ACS

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