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Optimizing Soy/Dairy BlendsOptimizing Soy/Dairy Blends

August 2, 2007

22 Min Read
Optimizing Soy/Dairy Blends

Photo: Wixon, Inc.

Theres an old saying that two heads are better than one, and thats often true in the world of formulating. Take soy and dairy ingredients. Often, dairy and soy products seem to compete against one another. Soymilk vs. dairy milk. Soy ice cream vs. dairy ice cream. Soy cheese vs. dairy cheese. Yet, just as retailers are beginning to place some of these products side by side on the shelf, food developers are finding certain applications benefit from using soy and dairy ingredients together.

Each can lend its strengths to a formulation, and the best protein and/or blend depends on the end result desired. Sarah Mulvihill, commercial director, Kerry Proteins & Nutritionals, Waukesha, WI, believes no protein fits all situations. The need for a blend to meet functionality requirements and/or nutritional requirements becomes more important, she says.

To optimize a blend, product designers need to understand what each ingredient brings to the development bench.

Definitely dairy 

When thinking about dairy ingredients, the layman might think milk. However, the food technologist will likely think casein, milk protein concentrate (MPC), nonfat dry milk, or whey protein concentrate (WPC) or isolate.

We always tell food manufacturers that whey delivers the triple playflavor, function and nutrition, says Sharon Gerdes, technical support consultant, Dairy Management, Inc. (DMI), Chicago. Whey has always provided a clean flavor. Current research supported by the DMI National Dairy Food Research Center Program shows how to optimize whey flavor in specific applications, such as high-acid beverages. She points to discoveries by Allen Foegeding, Ph.D., William Neal Reynolds Distinguished Professor, Department of Food Science, North Carolina State University, Raleigh, who has determined that astringency of whey proteins at low pH is related to the positively charged whey proteins binding with negatively charged proteins in saliva. The group has explored the possibility of modifying whey proteins by binding sugars to the positively charged amine groups, thus removing the charge and making the protein less attractive to saliva proteins and less astringent. This is just one example of how whey protein technology is constantly improving.

Modification can tailor a whey protein to provide or enhance a specific functionality, such as heat stability, gelation, texture, clarity and acid stability. For example, Only whey proteins are stable under low-pH conditions, explains Grace Harris, manager of applications and business development, Hilmar Ingredients, Hilmar, CA. Dairy proteins that contain casein (caseinates and MPC) will precipitate in solution when the pH drops toward the isoelectric point (the pH where the protein carries no charge). Because they alone remain stable, whey proteins are the protein of choice in beverages with pH levels as low as 2.5.

This expands dairys application range. Adding protein to juices and water is very popular now, says Gwen Bargetzi, director of marketing, Hilmar Ingredients. Whey protein isolates are ideal for these types of drinks. Their acid and heat stability allow them to easily withstand the rigors of low-pH juice fortification and standard pasteurization.

Dairy proteins can also be used to lower fat content. Salad dressings provide a good example. The usage level is going to vary, says Gerdes. For instance, a fat-free, thousand island dressing uses 5% WPC 80 to provide fat replacement and creaminess. A caesar dressing would use 7.6% WPC 34, and a poppy seed dressing uses 5% WPC 34. In salad dressings, whey not only provides a nice dairy flavor, but also works functionally to increase creaminess, emulsification and viscosity.

Nutritionally speaking, dairy proteins are complete; they contain all the essential amino acids required for human consumption. Whey protein has a PER of 3.2 and PDCAAS of 1.00 and <1 for whey protein isolates, says Bargetzi. Whey protein concentrate typically has a protein of 34% to 80%. Whey protein isolate is usually 90% protein. The PER of milk is 2.7. The PDCAAS is 1.0.

Ultra-filtered (UF) milk contains higher levels of protein and lower levels of lactose and minerals than skim milk. The dried form is called milk protein concentrate; the liquid form is called ultra-filtered milk, says Gerdes. No standards of identity exist for either MPC or UF milk. MPC is produced in protein concentrations from 42% to 85%. UF milk can be custom made, she says. It is usually described by the term volumetric concentration factor (VCF) and might range from 2 VCF to 5 VCF. A typical UF milk might contain 10% to 12% protein and less than 5% lactose. With the added step of diafiltration, the UF milk can reach 16% to 17% protein and less than 1% lactose.

Formulators may want to consider the types of proteins in UF milk. There are many studies supporting various health benefits for the different components of milk, as well as milk as a whole food source. Our ultra-filtered dairy proteins contain both the casein and whey portions of milk in their native state, says Mulvihill. Whey is known as being a good source of branchedchain amino acids (BCAAs) as well as an anabolic protein source. Native casein (in its micellar state) is a satiety protein and helps prevent muscle breakdown (anti-catabolic proteins).

Newer research from DMI shows that whey protein independently stimulates muscle synthesis. The good news is that whey proteins augment new muscle protein synthesis after resistance exercise, explains Gerdes. There has been some debate among athletes about optimal time to consume protein in relation to exercise. The research now shows that the proximity to exercise is whats important, not whether its consumed before or after exercise. DMI research also shows that whey protein improves satiety.

Specifically soy 

Consumers are increasingly becoming aware of soy products. In the 2006 report, Consumer Attitudes About Nutrition, sponsored by the United Soybean Board, Chesterfield, MO, 87% of those surveyed were aware of soymilk; 28% were aware of soy ice cream; and 23% were aware of soy breakfast cereal.

According to the report, 30% of

Dairy ingredients, including casein, milk protein concentrate, nonfat dry milk and whey protein concentrate, provide flavor, function and nutrition in a range of applications.
Photo: Dairy Management,

Americans consume soy-foods or soy beverages once a month or more, and 82% rate soy products as healthy, significantly more than previous years. Consumers recognize soy-foods and beverages for their low-fat profile (20% of consumers surveyed), protein content (15%), heart-health function (15%), cholesterol- lowering properties (12%), and generally being good for you (10%). Whats more, the report states, an increasing number of consumers (31% in the 2006 online survey, compared to 27% and 26% in the 2004 and 2005 telephone surveys, respectively) specifically seek out products containing soy for health reasons.

Soy has risen in consumers awareness in part because of FDAs approved health claim for soy protein, which states: 25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease. While soy protein is low in saturated fat, research suggests there is more to the heart-health story. Soy protein lowers triglyceride levels and raises high-density lipoprotein (HDL) cholesterol. Studies have shown that soy protein stimulates the liver to remove low-density lipoprotein (LDL) cholesterol from the blood. This provides a compelling reason to add soy protein.

Soy flour has approximately 50% protein. Soy protein concentrates have at least 65% protein on a moisture-free basis. Soy protein isolates are 90% protein by dry weight. Soy is a complete protein from plants with a PER of 2.0 and a PDCAAS of 1.0, making it equivalent to meat or eggs in quality. But what makes soy unique is that it is rich in phytonutrients, especially isoflavones, beneficial bioactive phytochemicals that are only present in significant amounts in soy. There are two important isoflavones: genistein and daidzein. A third isoflavone, glycitin, is present in small amounts.

A word of caution: Those looking for isoflavone benefits need to be aware that alcohol extraction diminishes soy proteins isoflavone content. Data on the USDA-Iowa State University Database on the Isoflavone Content of Foods1999, illustrates the difference. Soy protein concentrate, produced by alcohol extraction, has 12.47 mg per 100 grams total isoflavones. Of these, 6.83 mg are daidzein, 5.33 mg genistein, and 1.57 mg glycitin. Aqueous-washed soy protein concentrate has 102.07 mg total isoflavones, with 43.04 mg daidzein, 55.59 mg genistein, and 5.16 mg glycitin. Soy protein isolate has 97.43 mg total isoflavones, 33.59 mg daidzein, 59.62 mg genistein, and 9.47 mg glycitin.

Soybean oil does not contain isoflavones, but it is an excellent source of fatty acids. Omega-6 (linoleic acid) and omega-3 (polyunsaturated alpha linolenic acid) are present in a favorable ratio of 7.5:1.

In addition to offering substantial nutritional benefits, soy protein provides functional properties for food product manufacturers, such as emulsification, gelation and whipability, says Mian N. Riaz, Ph.D., director, food protein R&D center, Texas A&M University, College Station.

Powerful unions 

The opportunities for blending the strengths of soy and dairy ingredients seem boundless. For example, Diehl Food Ingredients, Inc., Defiance, OH, combines soybean oils with dairy proteins, such as caseinates and skim milk solids, and then spray-dries these emulsions, says Joan E. Hasselman, R&D manager at the company. These appeal to the formulator and/or consumer who wants healthier unsaturated and low or no trans-fat vegetable oil vs. dairy fat, but wants the benefit of having protein in a product, she suggests. The spray-dried emulsion product mimics the properties of milk, such as great whitening power and creamy mouthfeel. Also, pricing may be attractive, as dairy products prices have recently increased significantly, she continues. Price, flavor and functionality often dictate the use of soy oil in nondairy creamers, whipped toppings, ice cream, frozen desserts and salad dressings.

Soy protein can also be used in nondairy frozen desserts, coffee whiteners and yogurt. In whipped toppings, soy protein aids in emulsification and aeration. Whey protein offers excellent foaming properties. Some dairy manufacturers are developing yogurt and ice cream products that contain a blend of soymilk and dairy, notes Riaz. However, he notes, since soymilk contains less carbohydrate for fermentation and flavor, soymilk cultured products need to be fortified with a sweetener.

Proteins serve a functional role in frozen desserts by inhibiting ice crystal formation. Whey proteins work particularly well in a slow churned or light ice cream, says Gerdes. In a standard ice cream you could use 2.75% sweet whey vs. 1% WPC 80. In a lowfat ice cream you could use higher levels, 5.1% sweet whey, 2.5% WPC 34, or 1% WPC 80. Obviously, as youre increasing the percentage of the protein, youre binding more water and inhibiting ice crystal formation.

Bakery is one area that often utilizes soy and dairy products. Bargetzi says bakery is a traditional, widely accepted application for soy, and one where soys use and benefits are established. However, she points out, new trends in bakerymore nutritionally dense food bars, high-protein snack foods for school lunches, breads and cakes more in tune with a GI-based dietare highlighting where whey protein should be part of the blend. With its functional support, excellent amino acid score and low GI, whey protein makes an ideal companion to soy in these types of applications.

They each bring their own functional benefits to the product. Concentrated and dry milk ingredients form and stabilize emulsifications, enhance water binding and machinability, enhance texture and perceived freshness, improve structure of baked products and contribute to browning. WPC aids in the dispersion of shortening, which can reduce the shortening level in some formulas or increase the effectiveness of shortening in others. WPC provides structure in bakery products through the formation of heat-set irreversible gels, lowers fat absorption in fried products and can replace egg albumin in many products.

Defatted soy flour acts as a crumb whitener and dough conditioner when used at less than 0.5%. At higher levels, 1% to 5% of dry ingredients, it enhances protein and improves cell structure in breads, doughnuts and bagels. It aids in moisture retention.

Baked goods formulations often contain dairy ingredients such as nonfat dry milk as well as soy flour. In chemically leavened products, whey protein can completely replace egg. In cake systems, a 50% replacement is recommended. The key for determining formulation amounts is to consider the total amount of protein to be replaced. If using liquid eggs, the water must also be replaced. Also, incorporating WPC 34 will add lactose, which will affect browning and increase tenderness. Soy flour can replace egg or milk proteins, although 100% replacement cannot always be achieved. Usage level is 1% to 5%.

Most protein products are very hydrophilic, so it may be necessary to increase water in a system to reduce batter and dough viscosity, cautions Ann Stark, senior applications scientist, Cargill Food & Pharma Specialties, Minneapolis. Its important to find the correct balance, though, since incorporating too much moisture can create an undesirable gummy and dense texture, which may require adjustment of other ingredients within the formula, she says.

Bargetzi says its important to remember that each type of protein, soy or whey, will impart specific functional and nutritional properties to the formula. Selecting the right addition level, or ratio if its a blend, can make the difference between a product that meets organoleptic and economic goals and one that falls short, she says. For any success-critical ingredient, one of the most important steps in your development process is to look for a supplier who demonstrates competent technical support and use them as a resource.

Bar basics 

According to Mulvihill, the most popular application for combining soy and dairy seems to be nutritional bars. Proteins have been mixed for functionality reasons, as well as having branded protein blends on the label, she says. High-protein bars can serve as meal replacements, act as dietary aids, give athletes a boost or provide a multitude of benefits, and the proteins chosen can enhance that image. For example, adding sufficient soy provides a heart-health claim and can include phytoestrogens that are appreciated by women for their estrogen-like properties.

Whey offers a fit body image, as evidenced by its longtime use by bodybuilders. In terms of the amino acid content, whey proteins have a higher concentration of branched-chain amino acids, says Gerdes. These BCAAs (leucine, isoleucine and valine) provide an energy source directly to muscles during endurance exercise, instead of being metabolized in the liver. They improve protein synthesis and reverse overnight muscle tissue catabolism, factors that can pique the interest of athletes and athlete wannabes.

Marketing aside, protein combinations impact flavor and cost. Generally speaking, dairy ingredients are higher in cost but more neutral in flavor. If you blend the proteins correctly you can optimize your costs without sacrificing functionality, says Max Maxwell, business development manager, Glanbia Nutritionals, Inc., Monroe, WI, which offers a balanced blend of whey and soy protein. He suggests including 2 to 25 grams per serving of this protein blend in nutrition bars and other products.

We use the range of whey proteins whey protein concentrate, hydrolysate and isolatesin our development work for cereals, beverages and bars, says Harris. They all have a particular contribution, whether functional or nutritional, to make in the system. What we find is that each formulation has nuances that influence the use level of whey protein, things like amount of soy addition, targeted label and market, as well as the overall desired end result. Some fundamental considerations for fine tuning the use levels include flavor, mouthfeel, shelf life and processing.

In bars, whey protein can bring shelf-life extension, texture modification, flavor improvements and, in the case of whey protein isolates, a high protein contribution. When we are in development with a customer, we consider the value/cost ratio of whey proteins as carefully as we consider its functional contribution, says Harris. In its interaction with soy, Id say whey proteins benefit comes from its ability to play well with others. It can assist in moderating flavor profiles, limiting grittiness.

Specifically, adding whey protein isolate to a bar will provide emulsion stability by reducing fat globule mobility to prevent oiling out. Yet shelf life is challenged with higher protein levels. Proteins tend to compete with other ingredients for available water in the formula, and the bar will harden over time.

One solution is hydrolyzed whey proteins, which are modified to break down the protein molecules into smaller whey peptides. While this results in less moisture being drawn away from other ingredients, the whey develops a slight bitterness. Luckily, in bar applications, this flavor is generally not an issue. The true benefit of incorporating hydrolyzed proteins is that high-protein bars can maintain a consistent texture for up to one year.

If protein fortification without affecting the base product is the goal, both whey and soy can be extruded or puffed to create nuggets or crisps that add nutritional texture to bars and cereals. These can be an alternative to grain-based puffs and crisps.

Beverage considerations 

Blending whey and soy in beverages is less common than in bars, but certainly an option, especially in pH-neutral beverages. The nutritional beverage market, which was traditionally dairy-oriented, has recently been using soy protein, mainly to help manage supply when using large amounts of protein in getting higher protein claim levels, says Mulvihill. With overall protein demand increasing year on year and the resulting tightening of dairy protein supply, soy is becoming an obvious choice for blending with dairy.

From a functional standpoint, whey protein contributes heat and acid stability, viscosity, flavor improvement, textural improvement and emulsification capability to beverages. However, various milk components provide different nutritional and functional uses. Examples of nutritional benefits might be anti-catabolism or humanization of infant formula, Mulvihill says. Functional benefits might be lower viscosity for high-calorie medical beverages. Similarly, for soy, we have a range of products with different functionalities, such as viscosity and dispersability.

There are a number of ingredient considerations for beverage development. For a dry-blended beverage, Mulvihill asks, Will the developer be agglomerating themselves or will the ingredients need to be instantized before making the blend? Also, the level of protein will be critical. She continues: How will the end user be using the product? Will it be multi-serve (and so possibly have a container open to moisture) or will it be single serve? Will it be reconstituted in hot or cold water? Will it disperse by simple stirring or will it need to go into a blender? Bearing all these in mind, a formulator may need a instantized or a standard protein, a nonhydroscopic product, or ingredients that disperse in cold or hot water.

For a ready-to-drink (RTD) beverage, initial batching and processing will be critical to ingredient selection. Will it be added in with cold or hot water? Will there be shear or not? What type of mixing? Mulvihill asks. Heat processing will also make an impact on ingredient choices. Lactosecontaining ingredients can cause a lot of browning with heat, she says. We often recommend lactose-free ultrafiltered MPI. Some products, like whey, can gel. In-process and final viscosity of the beverage is also critical, and so different ingredient recommendations may be needed, depending on the system being used, she continues. To help RTD beverage manufacturers, we have hot- and cold-soluble proteins, lecithinated versions, different dispersabilty, water uptake and viscosity characteristics, high heat stability and low-sugar-containing products.

Bargetzi cautions its important for dry-mix beverages sold on volume in a canister to have consistent and appropriate bulk density. This is instrumental when addressing packaging quality, she says. Material thats too fluffy wont fit in the can, and too little material looks like an under-fill to the consumer. Manufacturing that consists of long production runs with large volume is ideal for delivering consistency in bulk density and other protein powder properties.

But, for beverages in general, the most critical consideration is pH. It is far more difficult to use soy proteins in high-acid beverages, Maxwell says. Again, the level of protein addition would hinge on how the beverage is to be marketed, but generally ranges from 1% to 10%.

Riaz acknowledges not all soy proteins will work in low-pH systems, below 4.5, yet some soy proteins are designed specifically for low-pH systems, he says. If they want to work with a low-pH system, food processors must ask their soybean processor specifically for a soy protein which can work at low pH.

In the lower-pH range, Gerdes suggests using a whey protein isolate for fruit-flavored, clear beverages. Whey proteins have an advantage in that they are clear and soluble at acidic pH, she says. When formulating creamy beverages at a higher pHfor example, strawberry, chocolate, vanillathen WPC 80 would be a good choice. The low levels of fat in WPC 80 actually contribute body and opacity to these formulas.

A recent study at the University of WisconsinMadison revealed that whey protein, if it is not denatured, is clear in solutions at pH 4.6 and below. Heat can cause proteins to become cloudy and precipitate, depending on the pH, says Gerdes. Typically, a hot-fill product is heated to 190ºF. They found that the optimal pH was 3.7 and below, and when you get above that, in the range of 3.8 to 4.0, it becomes more critical. Interestingly, the researchers found that the type of sweetener was very important, and that sugar alcohols actually produced a clearer solution. So, if someone were trying to develop a sugar-free high-protein beverage, they might consider sugar alcohols. Also, in isotonics, especially a sports recovery beverage, minerals are often important. This research found that adding sodium, potassium and calcium solids actually decreased clarity, whereas adding amino acids increased clarity, she says. So, the selection of the overall ingredients and the formula is important.

At the 2005 Institute of Food Technologists (IFT) Annual Meeting & Food Expo in New Orleans, The Solae Company, St. Louis, asked attendees to participate in a blind taste test of two vanilla meal-replacement beverages, a dairy protein version and a soy- and dairy-protein blend. Both were formulated to contain 10 grams of protein per 11-oz. serving. The all-dairy version included a combination of nonfat dry milk and calcium caseinate, and the blend contained 20% soy protein, which replaced all of the caseinate. The results showed 60% preferred the soy and milk combination compared to the all-dairy beverage, which mirrored the companys internal consumer panels.

In a company release, Jean Heggie, marketing leader, North America Food, Solae, says that blending soy and dairy is a great option for food manufacturers looking for relief from high milk ingredient pricing and looking for new marketing opportunities centered on the complementary benefits of milk and soy.

Product possibilities 

There are many formulating and market opportunities for products containing soy and dairy. Mulvihill sees potential for satiety and/or weight-loss products and heart-health products. Better-for-you snack products seem like a good option, especially as we have found that both our soy and dairy proteins extrude really well, so you have the ability to add into the actual product matrix, as well as nutritionally enhanced seasonings, she says.

Its important to remember the United States is sometimes slower than other parts of the world to embrace blends. In South Africa and Mexico, for example, it is common to blend soymilk with regular milk, Riaz says. These popular blends are made in a variety of flavors.

Mulvihill notes: The majority of our dairy protein is used in applications where soy is being used already or is being considered. A number of global nutrition brands in particular have been using these combinations for the last couple of years. Dairy may have been in the majority internationally a few years ago, but because we have non-GM and organic soy available to us, this opens up international markets to our product and combinations also. The interest is certainly increasing.

Cindy Hazen, a 20-year veteran of the food industry, is a freelance writer based in Memphis, TN. She can be reached at [email protected].

In Beverages, Flavors the Thing

All food and beverages succeed or fail on the basis of their flavor quality and appeal. Beverages made with soy and dairy proteins are no exception to this rulein fact, given the current product proliferation, its essential the flavor scores a knockout with the first sip. And while no hard and fast rules exist, according to Elaine Kellman Grosinger, director of research & development, Citroil Enterprises, Carlstadt, NJ, a number of factors influence flavor selection.

Type and level of soy: Technology has yielded specialized soy protein ingredients with vastly improved flavor profiles. So, while soy has a reputation for poor flavor, thats not always true, says Grosinger. But, if an off-flavor is present, in general, vanillas work well, and some fruit flavors can also cover the soy-beany notes, she says. However, sometimes it takes creativity to find ways to cover any flavors from the base.

Product pH: Cows milk has a pH between 6.5 and 6.7, and soymilk tends to also fall in the nearly neutral category. When flavoring these types of products, Grosinger recommends chocolate, coffee and caramel. Any brown, sweet flavor will work well, like vanilla hazelnut, chocolate hazelnut, almond and any combination, she says, adding that some fruits, such as banana, peach and mango, also would work, because they are sweeter. In addition, less-acidic fruits can work to cover any beany notes. On the other hand, many fruit flavors benefit from a lower pH. For example, fruit smoothies often have a pH in the area of 4.5 or so, with flavors like strawberry, raspberry and pineapple typically enhanced by a slightly lower pH than flavors like banana and peach, she says. Furthermore, its rarely a good idea to assume a flavor translates well from one pH range to a dramatically different one, she warns.

Clarity: Protein beverages can be clear or opaque, with the opaque types providing an expectation of richness, and the clear types generally signaling refreshment. However, according to Grosinger, any flavor can be modified to fit any base, opaque or clear, but, typically, opaque beverages are synonymous with strawberry, mango, peach, etc. These are popular in a creamy, smoothie-type beverage. A clear beverage can use any flavor as long as it covers any off taste. Typically, tea and fruit flavors meet expectations with a more-refreshing flavor.

Fat content: Products with higher fat levels will modify the flavor by coating the tongue and changing the flavor delivery, smoothing it and rounding it, says Grosinger. For nonfat or low-fat soy and dairy beverages, the flavor delivery may be lacking. Sometimes, fat content improves the flavor, she says. Low- or no-fat is more difficult to flavor, typically. But you can add some mouthfeel notes to the flavor, like lactones, and other fat-mimicking chemicals to fool the tongue.

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