Fiber Goes with the Functional Beverage Flow

When fortifying beverages with fiber, it’s important to take the product’s pH into consideration. Modified, stabilized fibers, such as some dextrins and fructo-oligosaccharides, are not as prone to hydrolysis in low-pH beverage systems as many other ingredients.

By loading fiber into the beverage products that consumers grab anyway, manufacturers bring more fiber fortification to the nation. “The beverage industry is very interested in learning how to add fiber as a strategy for making label claims,” said Niba, adding the challenge is to build a level of fiber into their products that allows them to make a strong label claim, and at the same time maintain a product that is acceptable to their core consumers in areas such as taste, texture and sensory quality.

Ironically, if it weren’t for the technical challenges, there might not be a more amenable medium for fiber fortification than beverages. The Code of Federal Regulations (CFR, Title 21, Part 101.54) allows a product to make a “good source” of fiber claim if it’s low in fat and provides at least 10 percent, or 2.5 g, of the daily value (DV) for fiber. To make an “excellent source,” “high in” or “rich in” claim, the same product must meet at least 20 percent or 5 g of the DV. Because “serving sizes for beverages are typically large compared to other foods,” Young noted, “this allows any given dietary-fiber ingredient to be added at a relatively low percentage use rate and still have less of an impact on sensory attributes.”

Additionally, FDA rules allow for a prebiotic claim for dextrin-based fiber: “If a product contains one quarter of the effective dose of the fiber per serving,” Niba explained.

Most beverage designers zero in on these levels because they get the job done nutritionally while not generating excessive costs or sensory drawbacks. “Many of our customers, especially in the area of dairy beverages, are looking to add fiber to their products,” said Jenny Diehl, food scientist, TIC Gums, “and most of these customers are asking for a level of 2 to 4 grams of soluble fiber per serving.” Because the ingredients she steers them to, including gum arabic and inulin, also “have very low viscosities, you can use them at a high loading level without seeing a difference from a sensory perspective.”

Indeed, if properly selected and applied, according to Young, a fiber ingredient can let you “formulate up to 100 percent of the daily value of dietary fiber—25 g per 8-oz. serving—and practically not even know it’s there.”

Perhaps the first issue to tackle should be a fiber’s acid stability. “Juices and most shelf-stable beverages have very low pHs,” Niba said. “Fibers, which are made up of complex carbohydrate molecules, are sometimes susceptible to hydrolysis in high-acid, low-pH systems.” The products of that hydrolysis—simple sugars—aren’t particularly perilous, but why fortify with fiber, and say so on your label, only to watch your beverage’s key functional feature decompose after a few weeks on the shelf? Young cautioned: “This can put any beverage at regulatory risk.”

Not all fibers show the same pH sensitivity. Inulin, with its mixed linear beta-2, 1-linked fructan polymers and oligomers, is among the more vulnerable. “Inulin does have limitations when it comes to beverage formulation,” Turowski said. “It’s a bit prohibitive in the sense that low-pH, shelf-stable products can be an issue.” However, once pH reaches 4.0 to 4.2 and above, “inulin can be stable in these products at room temperature for a year of shelf life,” he said. Furthermore, pH is a threat “only at ambient temperature. So if you’re talking about refrigerated products, that’s not an issue, and we can start fortifying things, like orange juice, that are at a low pH.”

Niba noted modified, stabilized fibers such as some dextrins and even shorter-chain species of inulin known as fructo-oligosaccharides, are not as susceptible to low pH. For example, the controlled acid, heat and enzymatic hydrolysis used to derive digestion resistant maltodextrin (DRM) from corn starch effectively “immunizes” it against acidic beverage conditions, as well as against the heat of retort, hot-fill or aseptic processing.

Those processing rigors are the second concern to address, as “some fibers are not stable to high heat,” Niba said. “Post-process shelf stability is another concern, as some fibers will slowly degrade over time in a beverage system.”

Many fiber ingredients are surprisingly robust in the face of these conditions. DRM dextrin-based soluble fiber and soluble corn fiber ingredients can withstand standard beverage processing and storage challenges.

Soluble corn fiber, manufactured using the same method that gives us corn syrup, is an example of just how much the world of fiber ingredients has widened. “It behaves a lot like corn syrup,” Schwenk noted. “We’ve always been aware of this small fraction of corn syrup that’s not digestible, and in most corn syrups, manufacturers try to minimize that fraction. But what we’ve done is change the reaction kinetics to maximize it so that now we have a high level of these nondigestible alpha-1,2 and alpha-1,3 bonds in the molecule.” Displaying corn syrup’s viscosity, but nearly none of its sweetness, adds not only fiber but bulk to beverages, making it a great companion to high-intensity sweeteners in formulations.

Even better, Schwenk said, “It dissolves just like sugar. It’s soluble at up to 80 percent, so there are no issues with functionality at a high level.” In fact, she continues, because it’s available as a pump-able liquid, it’s useful for beverage manufacturers already working with liquid high fructose corn syrup (HFCS). “You don’t even have to dissolve it because it is already dissolved so it hides even in applications as naked as bottled water. You can’t taste it and you can’t see it and you can’t detect it when you drink it,” she said.

Online Bonus: A section on issues and challenges facing the use of insoluble fiber in functional beverages will be added to the online version of this article at NaturalProductsINSIDER.com

Kimberly J. Decker, a California-based technical writer, has a B.S. in Consumer Food Science with a minor in English from the University of California, Davis. She lives in the San Francisco Bay area, where she enjoys eating and writing about food. You can reach her at kim@decker.net.

Editor’s Note: The full version of this article originally appeared in the Oct. 2007 issue of INSIDER’s sister publication, Food Product Design. Visit FoodProductDesign.com for more on product formulation and the beverage market.