Manipulating Mouthfeel in Beverages

[Beverages] Sept/Oct 2013 ww Manipulating Mouthfeel in Beverages

By Teresa Esquivel, Managing Editor

If you've heard it once, you've heard it a thousand times: Flavor is everything. But is it? The flavor of a food or beverage plays an important role in whether the consumer comes back for more, but it's not the only factor that contributes to the appeal of a product. When it comes to consumer acceptance, mouthfeel runs a tight second to flavor.

"Often, foods will be rejected if they do not 'feel' right when they are being consumed," says Lorelie McRae, food technologist, Gum Technology Corp., Tucson, AZ. In the beverage category, "examples of this would be soda that is 'flat' or a protein drink that is 'grainy,'" she says. "Even if a carbonated beverage has great flavor and is sweetened properly, it will be rejected if the carbonation level is inadequate. Consumers expect a certain 'pop' when consuming their soda pop, and if that is not present, the beverage will be considered unacceptable." Further, she says, protein drinks and meal- replacement beverages are expected to be creamy and smooth, so those that are chalky, grainy or watery will likely be rejected. Sports drinks, on the other hand, are expected to have a consistency close to that of water.

As its name implies, the mouthfeel of a beverage refers to the way it feels in the mouth, from the time it first touches the lips to after it is swallowed. "This includes not only viscosity, but lubricity and friction force," says Vince Cavallini, beverage applications manager, Cargill Inc., Minneapolis. "When you think of how a beverage rolls over your tongue and goes between your gums and teeth, that's not just the viscosity, or thickness, you're feeling, it's lubrication and friction."

Mouthfeel descriptors might include astringency, mouth-coating, mouth-clearing, creamy, slimy and watery.

Just right Because consumer acceptance hinges on mouthfeel, getting it right is a big deal, especially in the booming beverage market. According to Beverage Marketing Corp., New York, the "liquid refreshment beverage market" in the United States grew by 1% in 2012, marking a third year of consecutive growth. That translates to total beverage volume of approximately 29.8 billion gallons of liquid refreshment.

To get their fair share of the market, beverage formulators spend considerable time on developing mouthfeel, using any number of viscometers, rheometers and sensory panels to help them nail it. Cargill, for one, uses tribology—"the science of friction and lubrication and wear"—to mimic and measure what goes on inside the mouth when a beverage is consumed, according to Cavallini. Before using this technology, "we could measure viscosity, but that would just give us one data point; we could tell if one beverage was different from another from a viscosity standpoint, but it didn't give us anything from a mouthfeel standpoint," he says. "For example, we've done a lot of work in trying to measure the mouthfeel components of different hydrocolloids. Two hydrocolloids may have very www.foodproductdesign.com Page 1

[Beverages] Sept/Oct 2013 similar viscosity, but one may be slimier than the other, so understanding which ones have better mouthfeel characteristics has allowed us to close the sensory gap between full sugar and diet beverages. Being able to measure this also helps cut down on costs and maybe cuts down the number of times you take a product to a sensory panel, which helps the speed to market." Another option for manufacturers is new sensory technology introduced by NIZO Food Research at IFT 2013 in Chicago. Called acoustic tribology, the technology—recipient of an IFT Innovation Award—records the sound of the tongue rubbing against the food, thereby measuring creaminess or astringency by the sound generated by the food interacting with the tongue during consumption.

Linked in These tools are useful, for sure, but manipulating mouthfeel begins at the bench. "Mouthfeel is the first thing you should focus on because, as you adjust your texture, you can change the flavor," says Dan Grazaitis, food scientist, TIC Gums, White Marsh, MD. "If you set your flavor first then decide you want to adjust your texture, your flavor will also adjust, so if you can set your texture, then build back your flavor, that's usually how you get the finished product the quickest." To complicate matters, mouthfeel is often confused with flavor. "If it doesn't 'feel' good, the individual often indicates that it doesn't taste good, even though the beverage may have a perfect flavor profile," McRae notes.

It turns out, this nugget of consumer perception is not too far off the mark. A multiyear research program from Cargill not only confirmed a connection between mouthfeel and consumer liking of a beverage, but also pinpointed how a beverage's components work together.

"We've identified three key components to beverages: flavor, sweetener source and texture," says Cavallini. "We call it the taste triangle, because the three components are interrelated. If you change your sweetener, you can also change the texture and the flavor. If you change the texture of your beverage, the sweetness may be more pronounced or it may be coming out in a different area of the sensory profile. If you change one component, you may change one other component, or both. In a beverage that is watery and thin, the flavor tends to go very quickly. But a beverage with a more full- bodied, rich mouthfeel will also have a fuller, better overall flavor."

Managing this interrelatedness is particularly challenging in "healthier" beverages, such as those with reduced calories or added nutrients.

"Meeting consumers’ expectations for mouthfeel can definitely be a challenge in any beverage system, but often with a healthier drink there are additional considerations," says McRae. "When you reduce the sugar, the drink loses viscosity, causing it to feel watered down. When fat is removed, the beverage can lose its rich and creamy mouthfeel. Another challenge is to keep heavy particles, such as proteins, in suspension. And, if a protein drink has a low pH, proteins can become denatured, causing them to precipitate out of solution, resulting in a grainy, uneven texture."

Select solutions Product developers often turn to hydrocolloids to help solve mouthfeel issues. Xanthan gum, for example, can increase viscosity. "This is beneficial if a cold process is desired, as xanthan does not require heat to hydrate and become fully functional," McRae says. If heat will be used, pectin is a www.foodproductdesign.com Page 2

[Beverages] Sept/Oct 2013 good choice. She recommends gellan gum to help with suspension and reduce precipitation. "Adding pectin or soy fiber to the drink before lowering the pH can help protect the proteins and reduce the grainy texture that accompanies protein denaturation," she notes.

Dairy-based beverages are expected to be smooth and creamy, regardless of their protein level. "An undesirable mouthfeel can affect the overall flavor profile of the beverages, and astringency can cause a puckering, drying sensation," says Shanna Smidt, business development manager, sports nutrition, Glanbia Nutritionals, Evanston, IL. "Whey protein is an ideal source of protein for a range of beverage applications, including neutral-pH, dairy-based beverages, as well as high-acid fruit drinks. Using the wrong whey-protein ingredients for dairy-based beverages can lead to insoluble and aggregated protein, which would result in undesirable turbidity or a white precipitate."

Glanbia Nutritionals offers pre-acidified whey protein that provides a more acceptable flavor profile, as the whey is less astringent. "Unpleasant astringent notes are most common in high-protein, low-pH beverages, which is why pre-acidification of protein is important," Smidt says. "At high acid levels (pH 3.0), whey-protein beverage clarity is manageable."

Meal-replacement beverages pose another challenge. In addition to carbohydrates and high levels of protein, these types of drinks also typically include added nutrients. "Vitamins and higher levels of protein can give you a gritty, grainy, harsher type of texture if you don't put something back in to build the creamy texture back up," says Grazaitis. TIC Gums, he says, offers a specialty hydrocolloid that is effective in meal-replacement beverages. "It smoothes out the texture," he says. "It's not really adding a lot of viscosity, it's just helping mask and smooth out some of the negative textures you get from the high protein and vitamin levels."

The ingredient can also help mimic the creamy texture lost in products where the fat content has been lowered or removed. "Creamy can mean a lot of different things, but usually it has to do with how a beverage clears the mouth, the viscosity and the thickness at different points—how thick it is initially and how thick it is at the end when you're swallowing," Grazaitis says. "It's usually a combination of different attributes. So, if you add one hydrocolloid to match the viscosity, then the mouthfeel is going to lack in other attributes, so usually you look at a combination of hydrocolloids to piece together a well-balanced, creamy mouthfeel." Usage levels are typically low when adjusting for texture, he says, so hydrocolloids will amount to just 0.1% to 0.5% of total formula.

Alternatively, some nutritional ingredients are processed so as not to negatively impact mouthfeel. For example, Glanbia offers a fine flaxseed ingredient that allows for omega-3 fortification "without graininess or textural issues," Smidt says.

In reduced-sugar beverages, it is imperative to adjust mouthfeel to meet consumer expectations. "Reducing or removing sugar from a beverage can cause a decrease in mouthfeel, but maintaining the sweetness level using high-potency sweeteners creates the perception of mouthfeel," says Adrienne Pohrte, food scientist, Tate & Lyle, Decatur, IL. "Most consumers perceive sweeter beverages to have more mouthfeel than less sweet ones. The challenge for beverage manufacturers in formulating products with less sugar is to give consumers the best of both worlds—less sugar but all the body and taste they love." www.foodproductdesign.com Page 3

[Beverages] Sept/Oct 2013

Sometimes, the addition of starch, hydrocolloids or fibers can help compensate for the loss of sugar solids, Pohrte says. Soluble corn fiber, for example, can improve mouthfeel as well as provide "transparent fiber fortification," she says, "because it is highly soluble and has very little color or taste."

Cargill's research has led to the development of a specialized blend of hydrocolloids that can replace mouthfeel in beverages where sugar has been replaced by a high-intensity sweetener. "We can actually quantify the difference between full-calorie and reduced-sugar beverages," Cavallini says. "As you add these hydrocolloids, we can actually show the sensory gap being closed. The closer you can get the texture to match the gold standard or full-calorie counterpart, the better consumers will like those reduced-sugar products."