Protein ingredients have been around for a long time, but thanks to the Atkins, South Beach and other low-carb diet crazes, this old stand-by is now a hot choice for beverages.

“Consumer awareness of low-carb diets is through the roof, and the demand for high-protein beverages has really increased,” says Kelly Czerwonka, marketing manager for Glanbia Nutritionals, Monroe, Wis., an international dairy ingredient company providing nutritional and functional ingredients, including whey proteins. “The trend is driven more by consumer demand than it is by product manufacturers. People are looking for high-protein options, and a beverage is a great way to get a high-protein, low-carb meal replacement.”

Soy and whey proteins are standard choices for makers of functional powder and ready-to-drink (RTD) beverages, including meal replacement beverages, sports nutrition and athletic performance drinks, weight loss beverages, soymilk products, infant formula, smoothies, drinkable yogurts and low-carb milk alternatives.

“With the low-carb trend, there has been a heightening awareness of the role foods and beverages can play in managing hunger, and in some instances, increasing attention on the glycemic index of foods and beverages,” says Jean Heggie, marketing leader, North America-food for The Solae Co., St. Louis, Mo., which offers beverage-makers a portfolio of soy-based ingredient solutions, including Solae soy protein. “Protein can play a significant role in products designed to deliver satiety and to be low-glycemic index.”

Both major protein ingredients are available to beverage manufacturers as a protein isolate, which is 90 percent soy or whey protein; a protein concentrate (70 percent protein in soy’s case, and 25 to 80 percent protein for whey); and wholebean powder (40 percent soy protein).

“For nutritional applications, formulators would be looking for an isolate,” Czerwonka says. “It’s great for things like high-protein sports beverages that bodybuilders or other serious athletes would be interested in, especially in the form of ready-to-mix powders.”

Protein ingredients are used for their nutritional value and for formulation purposes, depending upon the source. Whey protein is valued for its essential branch chain amino acids, which appeal to athletes, as they help build muscle. Its bioactivity is another benefit; whey protein can be processed to smaller and smaller fractions, which have been shown to have immune-enhancing and intestinal health properties, making it useful in the formulation of nutraceuticals.

As the only high-quality, plant-based protein, soy has a variety of nutritional benefits. Similar to whey, it contains all the essential amino acids that support human growth and development. Soy is also thought to help prevent certain types of cancer, improve bone health, ease certain menopausal symptoms and assist in weight management.

“Soy protein also has a very healthfull perception among consumers — more than 74 percent of consumers perceive soy as healthy,” Heggie says. That perception has driven development of soy-based beverages in recent years; refrigerated soymilk grew 18.6 percent in sales in mainstream supermarkets in 2003, and soy protein is being used more extensively in juice-based beverages, such as V8 Splash Smoothies.

Soy holds an important advantage over whey: an FDA-approved health claim, which states that consuming 25 grams of soy protein a day, with a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. Thus, adding a soy ingredient can help beverage-makers to more effectively market finished products to health-conscious consumers.

“Soy protein ingredients are incorporated in beverage systems for a variety of reasons,” says Lisa Scott, beverage technologist for Archer Daniels Midland Co., Decatur, Ill., a provider of functional soy protein isolates and concentrates and organic wholebean powder. “From a nutritional standpoint, soy protein is an excellent source of amino acids, a good source of dietary isoflavones, and is cholesterol- and dairy-free.”

While there is not currently a health claim for whey protein, the ingredient is getting more attention these days. Recent research, highlighted by the “3-A-Day of Dairy” and “24/24 Milk Your Diet. Lose Weight!” advertising campaigns, shows that dairy products, and by extension, whey proteins, help with weight management. Additionally, whey proteins contain naturally occurring calcium, which helps maintain bone health and prevent osteoporosis.

“People are becoming aware that whey protein not only provides the benefits of high-quality protein and calcium, but that it also has bioactive components that are capable of improving health and preventing disease,” says Marcela Cota Rivas, technical and nutritional development manager for Vitalus Nutrition Inc., Bellingham, Wash. “These components have been linked to raising natural antioxidants in your body, like glutathione, due to their high concentration of cysteine, which serves as a substrate for glutathione synthesis.”

As with any ingredient, beverage-makers must choose a protein based on the impact it will have on the finished product, particularly how it will react with other ingredients and how it affects color, flavor and shelf life. Understanding the profile, processing conditions and product composition helps ingredient providers to work most effectively with beverage manufacturers to choose the right option.

“You have to know what product you want, what you want it to look and taste like, and what market it is for,” Cota Rivas says. “It also depends on whether you’re talking about a powder or a liquid RTD beverage, because there are different considerations for each.”

Generally, protein concentrates are used in thicker beverages, whereas isolates produce a thinner-bodied drink to which a thickening agent is sometimes added. Powdered beverages tend to be easier to formulate and develop because they have a longer shelf life than liquids and can be flavored more easily. RTD beverages fall into two categories: neutral pH beverages, which are cloudy and milk-like, and acidic pH drinks, which are juice-like and typically clear.

“The addition of soy protein to a neutral beverage that is normally flavored and colored, such as strawberry or coffee, has very little impact on color,” Solae’s Heggie says.  “When adding it to a fruit-based product, it will make the beverage generally cloudier in appearance. Depending on the level of incorporation and type of beverage you are working with, protein-containing beverages also are generally more viscous. However, significant impacts on viscosity are rarely seen at relatively low inclusion levels.”

Processing also has an impact on what type of protein beverage-makers choose. Beverages undergoing high heat treatments like UHT require a heat-stable protein that would remain in solution—a criterion not all proteins can meet. Soy, for example, can’t be used in clear beverages because it forms colloidal dispersions in water; however, it does enhance viscosity, making it attractive for use in milkshake or foamy-type beverages, drinkable yogurts and smoothies.

“When you’re developing a neutral pH beverage, you have a choice between whey proteins or milk protein concentrates,” Vitalus’ Cota Rivas says. “That’s because at a neutral pH, clarity in solution is not so important since these types of drinks are usually cloudy or opaque. However, you do have to consider the heat treatment, which will depend on the desired shelf life. A refrigerated drink will not need a heat treatment as extensive as an ambient temperature shelf-stable drink.”

Whey protein’s solubility makes it particularly useful for RTD beverages. Often when beverage-makers attempt to boost a beverage’s protein content, a phenomenon called protein flocculation can occur, or the added protein falls out of solution, causing the ingredient to settle on the bottom or float around the beverage. Because this is unappealing to consumers, whey proteins are often used because their high solubility negates this issue.

One of the biggest problems formulators face in incorporating whey into a clear drink is its tendency to increase in viscosity when heat-treated. Vitalus is focused on this area, having developed a heat-stable whey protein isolate called Inpro 90 HS specifically for clear RTD beverages undergoing UHT, retort or hot-fill processes.

“The main problem formulators face in developing RTD beverages is the destabilization of the protein during storage, which causes gelling and cloudiness. One way to overcome this has been to lower the pH in the whey protein solution; however, shelf life is compromised because you’re forcing the protein to remain soluble at a certain pH without properly stabilizing it,” Cota Rivas says. In such cases, formulators are successful in getting a clear drink at the beginning, but the protein precipitates as shelf life progresses, causing cloudiness as the pH rises because the protein is unstable.

Color, clarity and flavor issues factor into beverage makers’ protein choices. For example, a clear sports beverage can’t have a cloudy appearance, so the manufacturer must select a type and level of protein that doesn’t interfere with the finished beverage.

“Whey is a very clean protein as far as flavor goes,” Glanbia’s Czerwonka says. “It has a light dairy flavor, so it doesn’t negatively affect the flavor of the finished beverage. It’s easily masked by light flavors like vanilla or strawberry, even when you bump up the protein content.”

As for soy protein, it displays dispersion characteristics, solubility, emulsifying capacity and builds viscosity when added to a beverage.Soy is typically less costly than its whey and casein protein counterparts.  

“Flavor and stability are key issues. Soy protein off-flavors are characterized as beany, bitter and astringent,” ADM’s Scott says. “Soy protein also has the ability to bind various flavor compounds, in particular, vanillin. Off-flavors can be overcome by proper soy protein isolate/concentrate selection, use of a soy masking agent/flavor, and incorporation of flavors that are efficient at masking soy.”

“Many of the flavors that are popular in beverages like chocolate, coffee and fruit flavors, in general, work quite well in soy-based beverages,” Heggie says. “Even vanilla, which was once considered a very challenging flavor for soy-based beverages, has come a long way in the past few years. We are continually addressing the taste issue with new and improved technologies and by working with flavor companies and others to develop improved flavor systems specific to soy-based beverages.”

In terms of stability, soy can be used in beverages that undergo processes including homogenization, HTST and UHT, although the protein must first be hydrated in 120-degree water for at least 15 minutes.

“Stabilizer selection is also key to achieving stability in soy protein beverages,” says Scott. “Neutral-base ready-to-drink beverages require carrageenan and cellulose gel whereas acidic ready-to-drink beverages require pectin. Locust bean gum, carrageeenan and xanthan gum can be used in powdered soy beverage applications.”

While nobody is sure how long the low-carb lifestyle will remain popular, it appears that, for now, whey and soy proteins will continue to appear in myriad new products.

In response to the Atkins/South Beach diet trend, Chelsea, Mass.-based HP Hood Inc. introduced its Carb Countdown low-carb milk substitute nationwide, and quickly expanded the line to include low-carb yogurt, RTD smoothies and juices. Such products have increased the use of whey proteins to provide a high-protein/low-carb combination because they are low in lactose, which adds to the carb count in regular dairy products.

“Drinkable yogurts and smoothie-type drinks are a growing category,” Czerwonka says. “There are so many on the market and new ones keep popping up. Kids like them, too, and many parents view them as healthy alternatives to soda. Looking at the refrigerated case, there were just a handful of drinkable yogurts a few years ago, and now there are dozens.”

Capitalizing on the soy trend, The Solae Co. recently launched a national television ad campaign to build awareness for its Solae brand. Titled “Protein in Unexpected Places,” the campaign aims to inform consumers that Solae is present in many beverages and foods, and encourages them to seek out products containing the branded protein as part of a more healthful lifestyle.

“The timing is perfect for the brand—Solae soy protein is now in a number of great-tasting, everyday foods and beverages that consumers can find on any grocery store shelf across the country,” Heggie says. “We also wanted to demonstrate to our customers that we don’t just produce the best ingredients for their foods and beverages, but we’re also an excellent marketing partner. In our ads, you’ll see products from customers such as Campbell’s, Snapple, 8th Continent and Gardenburger.”

No matter what the low-carb diet plan, it appears that the number of ways to get a protein fix through beverages is going to keep growing.