Legumes = resistant starch + fiber
The similarity of resistant starch and fiber is described in the February issue of the Journal of Nutrition, by the University of Illinois, Urbana, research team headed by George Fahey Jr. Fahey, et. al. report legumes contain substantially higher percentages of resistant starch than do cereal grains, flours and grain-based food products. Resistant starch was equated to dietary fiber in that both bypass digestion in the stomach and small intestine before settling in the colon. Bacteria present in the human gut attack resistant starch as they do dietary fiber, producing butyrate.
Butyrate is a short-chained fatty acid which has shown cancer-preventing qualities. The Illinois study provides the first database of the percentages of starch and fiber in common food and feed ingredients. The researchers also determined how and where in vitro digestion occurred by studying digestion in the lower part of the small intestine in a dog model representative of the human digestive tract.
"The nice thing about legumes is they have a great deal of dietary fiber plus the resistant starch," said Fahey. "With their protein, fiber and resistant starch, legumes offer good nutrition. Until now, we never knew legumes had so much of their starch in the form of resistant starch."
Of the 29 food and feed ingredients studied, the legumes (seven varieties) contained substantially higher percentages of both dietary fiber and resistant starch. Black beans, for instance, contain the highest amount of total dietary fiber (43 percent), and 63 percent of their total starch content is resistant starch. Frozen green peas, when cooked, contain about 26.3 per cent resistant starch as RS1 and RS3.
Resistant starch sourcing options
MGP Ingredients Inc. (www.mgpingredients.com), Atchison, Kan., for some time has been producing resistant starches made from wheat and potatoes. Its Fibersym family of products feature low water-holding capacity and total dietary fiber ranging from 70-80 percent. Because they are derived from wheat and potatoes, they possess a neutral flavor, white color and smooth texture, and as a result can be incorporated into a wide range of foods, such as bread, tortillas, muffins, waffles, breakfast cereals, cookies, nutritional bars and snack foods.
MGP also has a business alliance with Cargill Inc. (www.cargill.com), Minneapolis, for the production and marketing of a resistant starch product called Fibersym HA. The product is derived from high-amylose corn and is suitable for use in a variety of lower-net-carbohydrate food products.
Cargill offered booth visitors a “high-fiber bun” at June’s IFT show that included ActiStar resistant starch … as well as a white whole-wheat flour, inulin and high-oleic sunflower oil.
Cargill’s European division Cerestar (www.cerestar.com), Mechelen, Belgium, introduced a tapioca-based resistant starch, ActiStar RT, in 2005. ActiStar RT is said to provide the benefits of high fiber in lower net-carbohydrate food formulations. Originally developed with an eye toward the low-carb market, the material is manufactured under an exclusive license granted by MGP. It is made by enzymatically debranching a tapioca maltodextrin and then causing retrogradation so the granules lose their crystalline structure, then aging the solution with cooling to form partially crystalline material that is not attacked by normal stomach enzymes.
ActiStar RT has low water-holding capacity, permitting high levels of inclusion with few formulation changes and a non-gummy texture. Since tapioca, the source of resistant starch in ActiStar RT, is the blandest of all starches it doesn’t detract from the desired taste, texture, or appearance of finished products. It is recommended for use in bread, cereal bars, biscuits, cookies and muesli. In beverages, low-fat fermented milks and ultra-pasteurized flavored-milk drinks can be successful vehicles for the product. Since ActiStar RT is a very fine particle, it blends easily with other ingredients and causes no grittiness. This makes it highly suitable for ready-to-use powdered mixes such as instant soups and chocolate drink mixes.
Sugar beets have been a source of fiber that behaves much like resistant starch but tests as fiber. Danisco A/S (www.danisco.com), Ardsley, N.Y., has recommended the use of its Fibrex sugar beet-based product as a fat replacer in meat products. Because much of the fiber is pectin, it produces a thick gel that behaves like fat in certain products. The sugar beet fiber is all natural, non-GMO, GRAS, USDA-approved in meats and poultry and HPB approved in Canada, and it can be obtained in an organic version.
Another fiber product line is the range of oligofructose and inulin products, made from chicory root or rice, produced by Orafti (www.orafti.com), Malvern, Pa. One of the company’s newer products, Beneo HP, is a partially hydrolyzed inulin dietary fiber that can be used to replace gelatin. Many of Orafti’s products are also available as organic products.
Corn resistant starch tests as fiber
National Starch Food Innovation (www.foodinnovation.com), Bridgewater, N.J., introduced Hi-maize resistant starches in 2002, although flour and meal from Hi-maize high-amylose corn were just introduced in March of this year. The products contain about 25 percent fiber, as tested by AOAC (Method 991.43 or 985.29 for insoluble fiber).