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Starch fractions in foods and in chemically modified starches: Concentrations and intestinal digestibility |
G. C. FAHEY, JR.1, E. A. Flickinger1, and B. W. Wolf2. (1) Dept. of Animal Sciences, Univ. of Illinois, Urbana-Champaign, 166 Animal Sciences Lab., MC 630, 1207 W. Gregory Dr., Urbana, IL 61801, (2) Ross Products Division, Abbott Laboratories, 3300 Stelzer Rd., 105670-RP3-2, Columbus, OH 43219-3034 Resistant starch can be defined physiologically as dietary starch that resists digestion in the small intestine and, therefore, is available for bacterial fermentation in the large intestine. Recently, it has been shown that resistant starch, in addition to traditional dietary fibers, may contribute significantly to the health benefits of plant-based diets. In addition to resistant starch, two other classes of dietary starch exist -- rapidly and slowly digested starch. Starch fractions can vary widely both in concentration and in composition in food ingredients. These starch fractions vary in rate and(or) extent of digestibility and may alter the digestibility of other nutrients. In addition, chemically modified starches are unique types of resistant starch that are gaining interest as food ingredients due to their ability to be tailor-made for specific food science applications. We have determined concentrations of rapidly and slowly digested starch and resistant starch in numerous foods and food ingredients. While starch concentration and starch fraction distribution varied due to type of substrate, our results imply that substrate processing alters starch digestibility, increasing concentrations of rapidly digested starch and decreasing concentrations of resistant starch. We also compared in vitro hydrolytic starch digestibility of chemically modified and unmodified starch sources. While extent of starch digestibility was decreased, the relative rate of starch digestion was not significantly affected. Although it is widely recognized that dietary starches are not completely digested in the small intestine, little information is available on the concentrations and relative proportions of resistant starch or rapidly and slowly digested starch in foods and food ingredients. Future research should focus on increasing the database on starch fractions in foods and food ingredients, as well as investigate the effects of processing and chemical modification on concentrations and relative digestibility of starch fractions.
Session 7, Resistant starch: A food ingredient with significant physiological and health benefits
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