Reduced-Fat Dairy Indulgences

Although fat is the source of much delight in decadent dairy creations, it can harm our health. Thankfully, growing consumer demand for reduced-fat versions of our favorites is being met with rapidly expanding options to lower fat without losing flavor and mouthfeel. At 9 calories per gram, fat more than doubles the 4 calories per gram of protein and carbohydrates. Milkfat is a key factor in organoleptic characteristics, including texture, structure, bite and mouthfeel.

Texture is a combination of factors related to “structure,” including viscosity, gel strength and character (elastic vs. brittle); bite (resistance to shear by the teeth); and “mouthfeel” (creaminess and lubricity).

Structure affects a product’s physical characteristics. “Ice creams are less stable as they have more water that needs to be controlled, thus higher levels of stabilizer are added, resulting in higher viscosity during processing,” says Joe Klemaszewski, dairy applications food scientist, Cargill Texturizing Solutions, Minneapolis. “Higher levels of protein are sometimes present in reduced-fat sour creams. These products also have higher processing viscosity.”

Not only does mouthfeel affect our perception of the product and its flavors. Klemaszewski also notes that increased protein in sour cream, which leads to higher viscosity, also causes a higher buffering capacity. “This can adversely affect flavor, as the product is perceived as being more tart,” he says.

Fat acts as a carrier for fat-soluble flavors. Many flavors have different perception thresholds in fat and water media, so fat removal can dramatically reduce or increase the flavor amount required to deliver the desired impact. Butyric acid, a crucial component of butter flavor, requires 7 ppm to be detected in water, yet only 0.6 ppm in oil.

Fat’s mouth-coating effect delay or prolong flavor release. Fats may also mask flavors or delay release due to variations in evaporation coefficients for flavor compounds in oil and water. In both cases, fat removal can lead to major imbalances in flavor, plus it can lead to a sudden burst of flavor, replacing the slow and steady release in the full-fat version.

On the level

Whole milk has 3.35% fat. Dairy products, however, exhibit a far greater range. Federal guidelines require that ice cream contain a minimum 10% milkfat. Typical products range from 10% to 17% fat, while premium products may contain 20% fat.

Yogurt made from whole milk is at least 3.25% milkfat. “Low-fat yogurt” with low-fat or part-skim milk ranges from 0.5% to 2.0% milkfat. “Nonfat yogurt” is made from skim milk, delivering less than 0.5% milkfat.

Labeling ice cream as “reduced fat” requires at least 25% less fat than the full-fat counterpart. “Low-fat” ice cream has 3 grams or less fat per serving. “Light” requires at least a 50% reduction in fat, while “fat-free” indicates less than 0.5 grams of fat per serving. Frozen yogurt does not have a federal standard of identity, but often has guidelines established on the state level: “low-fat frozen yogurt” is made from milk with 0.5% to 2.0% milkfat, and “nonfat frozen yogurt” is made from milk with less than 0.5% milkfat.

The pretenders

Transforming water into a suitable fat stand-in has become a science in itself, giving rise to ingredients and ingredient systems that create the illusion of fat.

Starches may be combined to mimic the creaminess of fat. Layering functionalities, developers can adjust two primary aspects of creaminess: mouth-coating and melt-away and allow developers to vary texture from that of a caramel to that of a pudding. Modified waxy maize starch plus modified tapioca starch yields high mouth-coating and low melt-away. Replacing tapioca with a specialized maltodextrin delivers low mouth-coating and high melt-away.

Gelatin, a protein derived from collagen, was the first commercial stabilizer. In ice cream, it helps assure proper overrun, manages ice crystal growth and slows meltdown. In yogurt, gelatin helps reduce syneresis. But gelatin is not the only protein of interest in low-fat products.

Functional whey proteins designed for specific flavor and texture attributes can “add an increased heavy, creamy mouthfeel that works very well in replacing the full mouthfeel and texture to mimic that of a higher-fat finished product,” says Michelle Ludtke, senior food technologist, Grande Custom Ingredients Group, Lomira, WI. She notes whey proteins “mimic the slippery mouthfeel and texture of a lower-fat product, which mimics a higher-fat counterpart.”

Studies conducted by Grande at the University of Wisconsin-Madison compared vanilla ice cream made with a 10% milkfat reduction. Replacing10% of the nonfat milk solids (MSNF) provided 10% greater overrun, improved ice and lactose crystal control, and improved melt characteristics. “With less milkfat and higher overrun, the functional-whey-protein-containing product exhibits a colder, denser, creamier texture,” says Ludtke. “More vanilla flavor can come through, as these specialized proteins do not mask flavors like the nonfat dry milk.”

Hydrocolloids can viscosify or gel water, providing an array of textural effects.

Carrageenan is a sulfated linear polysaccharide, extracted in three forms from Rhodophyceae-type seaweeds. Kappa and iota carrageenans provide rigid or elastic gels, respectively, while lambda just thickens. Carrageenan in low-fat chocolate milk creates a light gel network that suspends cocoa particles and provides a rich, creamy texture despite low fat levels. More-complex systems often benefit from carrageenan blends to achieve optimal texture―combining kappa and iota merges rigid and elastic gelation for a strong gel with good syneresis control.

Strong interaction with calcium helps alginates add unique texture to ice-cream. This interaction can, however, result in precipitation if a sequesterant is not used. Alginates improve resistance to freeze/thaw and stabilize fat dispersion.

Xanthan gum is a long-chain polysaccharide that provides thickening across a wide pH range. It can behave like an emulsifier, providing suspension and emulsion stability. Also referred to as “shear-thinning,” xanthan’s tendency to decrease viscosity under shear and increase viscosity at rest can be a benefit when pumping or extruding soft-serve ice cream. However, levels greater than 0.04% can cause an unmanageably thick mix and a chewy-textured ice cream.

Locust bean gum (LBG) and guar gum are thickeners with similarities and differences. Guar gum hydrates well in cold water, while LBG requires temperatures at or above 170ºF for complete hydration. Guar gum provides thickening at lower cost than LBG. Guar does not interact strongly with carrageenan, though, and does not provide the same level of protection from heat-shock-related deterioration as LBG.

Mix and match

Blending stabilizers can create specialized characteristics for particular products and environments. “In ice cream, the combination of modified and unmodified starches and colloids selected to be compatible with the entire system provide body and texture, while the judicious use of emulsifiers aids in air incorporation and helps stabilize against freeze/thaw damages,” says Bill Shazer, director of R&D, Tate & Lyle Custom Ingredients, Decatur, IL.

“In cultured products,” Shazer continues, “fat and nonfat milk solids may be partially replaced using a unique co-processed blend of whey solids, maltodextrins, modified food starches and hydrocolloids to achieve desirable body and texture, creaminess, and clean dairy flavor.” Soluble corn fiber provides opportunities for improving body and creaminess of yogurt while adding nutritional benefits.

Combined with specialty starches, xanthan can create a creamy texture in low-fat yogurts. Blending guar and LBG provides an economic benefit over LBG alone, and increases ice cam’s viscosity and overrun. Carrageenan and LBG can control melting characteristics. Adding guar creates a protective colloid system that helps prevent “wheying off,” casein precipitation, through processing.

Joshua Brooks, vice president, sales and marketing, Gum Technology Corporation, Tucson, AZ, suggests blending several stabilizers makes use of the synergies hydrocolloids have with each other, as well as other ingredients—particularly cellulose gel, konjac, sodium alginate and xanthan. “It is a gel-formed fat mimic which provides the creamy texture, mouthfeel and body which fat would provide. The gel is created by the synergistic cross-linking on the molecular level of the individual hydrocolloids,” he says. “Furthermore, there is a reaction with the calcium components in the dairy formulations and the sodium alginate in the gum blend. This imparts an additional gel formation, or structure, which simulates the removed fat content.”

Brooks notes that one key benefit to gums is low usage levels. “Because usage levels are typically as low as 0.10% to 0.75%,” he says, “there is no flavor masking as you might get if starches were to be used. So, in a low-fat mousse, you might use the stabilizer at 0.20% to 0.30%. In a low-fat yogurt, you could use as low as 0.2% to 0.3%.”

The landscape for low-fat dairy products is evolving with consumers’ tastes. According to Donna Klockeman, Ph.D., dairy food scientist, TIC Gums, Inc., Belcamp, MD: “Buzz is building based on product innovation by Pinkberry and Red Mango—new and different low-fat frozen yogurt. This also represents a departure in eating occasion, adding frozen yogurt to the breakfast menu. We are seeing requests—whole product formulations, processing, ingredient systems—for these low-fat frozen-yogurt products that have a different flavor profile and/or are probiotic.”

Luckily for consumers, one area the industry is not slimming-down is innovation.

R. J. Foster is a wordsmith with a B.S. in food science from the University of Wisconsin-Madison and over 15 years of experience in the food industry. He can be reached through his website wordsmithingbyfoster.com.