Boosting Protein Content

Improved mouthfeel may result from added whey protein in such a system. Bastian notes that when a stabilizer was incorporated at a high enough concentration to disperse the ground flax, the beverage was too thick. “It almost became slimy,” he says. “When we dropped the stabilizer back again without the whey in there, we thought the particles weren’t suspended as well as they should be. But, by doing a combination of whey and stabilizer, we were actually able to get a fairly nice mouthfeel in that beverage.”

Partially hydrolyzed whey proteins can increase shelf life of bars. “Intact proteins in these bars tend to harden over time,” says Bastian. “By manipulating that protein system, you can create softer bars. Shorter peptides have some effect. In lower-protein bars, you can probably do the job with your standard humectant glycerin and your selection of your sweetener, and you can probably maintain some softness.” But increasing that level of protein presents a harder challenge. “As you increase the protein in a bar, the hardness issues are going to be exacerbated,” he continues. “You need to make sure that you select the appropriate proteins so that you can maintain softness.”

An off-the-shelf WPC80 or WPI will not necessarily maintain softness across the shelf life. “We’ve spent a lot of time working on developing protein products for bars,” says Bastian. “Even if you buy a standard WPC80, which is a commodity, it’s variable from manufacturer to manufacturer. When you’re talking about a more-specialized product, like what you would want to put into a protein bar, absolutely there are major differences in product from manufacturer to manufacturer, and even within one manufacturer there are differences.

“We offer about four different types of protein systems for bars, and each one of them has its own niche area and unique benefit,” Bastian continues. “When we talk to our bar customers, we first of all have to try to find out what kind of bar are they making. What’s the protein level? What’s the coating? Are they putting any kind of nuts or chocolate on the bar? All of these things have a bearing on what you’re going to select to put into it.”

Harris says food bars rely on several facets of whey protein, from texture and shelf-life improvements to nutritional quality. “One of our basic bar formulations can be tuned to deliver up to 30% protein,” she says. “This formula uses whey in a combination with different milk proteins, and even soy proteins in some cases. We do that because we know each protein can contribute different advantages, and because orchestrating the proteins achieves a specific profile to suit each customer’s objective for their bar.”

Selection of a protein for a beverage depends on its pH stability and its sensitivity to heat. “Solubility of whey proteins is excellent across the pH range, unlike other milk proteins that contain casein,” Harris says. “These will precipitate at pHs approaching 4.⁶ (isoelectric point). The isoelectric point for whey protein is typically between 3.⁵ to 5.2. This upper end is where you may see some destabilization of the protein.”

The isoelectric point is the pH point where the charge on the protein is neutral. “As we go below that isoelectric point, they become positively charged and they start to repel each other,” says Bastian. “We found that around pH 3, they are strongly, positively charged. Even though you heat them, they still denature or unfold, but they don’t aggregate at that pH. So the two major areas where whey proteins have been used in beverages is, first, in the acidic range, pH 3, and then in the neutral pH range, pH 7. The more-difficult pH range is the one around the isoelectric point. The whey proteins are pretty soluble at their isoelectric point as long as you don’t apply heat to them, but when you start applying heat, they start to precipitate. Then that causes issues to try to make a beverage that’s, say, at pH 4 or pH 5. We don’t have a lot of examples of whey protein beverages in that mid-pH range. It’s a difficult range to work in.”

Clear protein waters are generally low-pH. “They call it water, but it’s actually an acidified water with a little bit of protein put into it—and of course they flavor it,” says Bastian. A typical formulation level is 1.0% to 1.5% WPI. “But, again, there is a wide range of protein inclusion into beverages. You go to more of a sports-nutrition, and we’ve seen as high as 45 grams of protein being delivered in one of the bodybuilding RTD beverages. Of course, that’s in the acidic range, and you have to push the pH even a little bit lower to get that high protein level in there and have it stable.”

Whey protein manufacturers have some tricks up their sleeves to increase heat stability. “Whey proteins, just as they come off the cheese, inherently are fairly sensitive to heat,” says Bastian. Controlling minerals and levels of hydrolysis are just a couple of the techniques in a protein manufacturer’s tool kit.

According to Harris, one word describes the trick to protein selection—discussion. “Always have an as-open-as-possible discussion with your supplier about what you want the protein ingredient to do, how you plan to process it, and what type of a nutritional profile you are trying to achieve,” she advises. “A good supplier—one who knows their protein ingredients’ composition and behavior—will give you the best recommendation for your application. Look for experienced technical support, resources and responsiveness. These three attributes will enable you to develop your product quickly and successfully.”

Cindy Hazen, a 20-year veteran of the food industry, is a freelance writer based in Memphis, TN. She can be reached atcindyhazen@cs.com.