The Search for a Better Fat Replacer: Swap in New Starches for Old Fats

Fat mimetics derived from carbohydrate or protein sources can perform the functions of fat at lower calories.

By Mark Anthony, Ph.D., Technical Editor

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Of the 474 extra daily calories we consumed in 2010 compared to 1970, 242 came from added fats and oils. Only 35 extra calories came from sugar. Flour and cereal products accounted for 181 of the extra calories.

Reduction of dietary fat is a powerful way to reduce total calories. However, doing so in a manner Americans will readily accept on a consistent basis has been a perpetual and considerable challenge. This is due to the way fats provide foods with physical and sensory characteristics difficult to mimic and to which Americans have become accustomed.

Fats influence melting point, viscosity, lubrication, volume, heat transfer and texture as well as the smoothness and creaminess crudely defined as "mouthfeel." A significant portion of the aromatic components inherent in foods are fat-soluble and are thus removed with the fat.

Fat mimetics are ingredients that do just as the name implies, mimic the functions of fat. We're talking mouthfeel, water-holding capability and other physiochemical aspects of formulation, production and organoleptic characteristics. Most fat mimetics are derived from carbohydrates or protein or involve a chemical alteration of fat molecules. They also can be a combination of these sources.

While carbohydrate- and protein-based fat mimics provide calories, they typically do so at not only less than the 9 kcals/g in fats alone but at less than the 4 kcals/g of their original components. Those derived from fat can provide zero calories as they are not digested and pass through the digestive tract.

Altered fats have generated some controversy owing to perceived side effects on digestion, but formulating on the low end of the calorie scale still can favor the use of carbohydrate- or protein-based mimetics.

Reduction of dietary fat is a powerful way to reduce total calories. However, doing so in a manner Americans will readily accept on a consistent basis has been a perpetual and considerable challenge.

There has been a considerable amount of research done into these types of fat replacers. An article published last year in the journal Meat Science  -- "Reducing the fat content in ground beef without sacrificing quality: A review" -- described ingredients that can replace saturated fats in meats. These included legume flours, like those from beans, chickpeas and lentils, as well as grain flours, like hydrated, cracked, waxy hull-less barley. The article also profiled starches from tubers like potatoes and cassava root (tapioca starch) that can be effective replacers.

A drawback to fat mimetics that have been based on starches is that they are not suitable for frying because of their high water-holding properties. Fried foods have high flavor and texture acceptability, and very high desirability among consumers. However, they also are another rich source of fat in the modern diet.

Mayonnaise, at over 70-percent oil, is the primary component in a wide variety of sauces and condiments and a go-to ingredient in restaurants and fast-food establishments. Last month, results of a study published in the journal Starch described how researchers in South Africa used the grains teff and maize as fat mimetics. As a medium, they created low-calorie mayonnaise-type emulsions (LCMTE). Starch from teff, an underutilized crop indigenous to Ethiopia, has many advantages that can fit into this category.

Teff is the grain of the traditional Ethiopian bread injira, similar to a crepe but with great elasticity in its completed form. A gluten-free grain, teff is one of the oldest domesticated plants and arguably the most nutritious grain available. It contains all essential amino acids, a rarity in grains, plus a variety of micronutrients, including calcium, phosphorus, magnesium, iron, copper, zinc and thiamin.

Teff starch has small granules (2-6 mm) compared to the starch granules from wheat and corn. This gives it slightly different properties from other grains. For example, researchers point to its increased thermal resistance and low tendency toward retrogradation, which can cause rubbery, weak-bodied gels.

The addition of 1.5 percent (weight/weight) stearic acid to both teff and maize starches reduces gelling behavior even further, while increasing viscosity. However, this modification is only necessary depending upon the desired level of fat replacement. For example, both modified and unmodified teff and maize starch can produce LCMTE with properties highly similar to mayonnaise at up to 50-percent oil replacement. However, if the goal is to reduce the fat content further -- e.g., to 80-percent oil replacement -- stearic acid-modified starches are then required to provide the physical properties of the full-fat product.

This article originally appeared in our October 2013 issue of Food Processing magazine.

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