22 - Methods to slow starch digestion rate in functional cereal products

Abstract

Starch, being the principal component in cereals and tubers, is the major carbohydrate related to postprandial glycemia and Glycaemic Index (GI) of foods. Carbohydrates modified for lower GI would be desirable as ingredients in functional cereal and other products for certain groups, that is, diabetics, and possibly for other improvements in general health. The current understanding of GI, particularly in relation to slowly digestible cereal starches—in terms of their structure and manufacturing approaches, is the focus of this chapter. Strategies for producing slowly digesting/low-GI functional cereal-based foods could include creating proper food forms and incorporating particular ingredients into foods, such as starches with the slow digesting property that extend glucose release, some non-digesting carbohydrates, Dietary Fiber (DF), Resistant Starch (RS), including viscosity-increasing polysaccharides that delay gastric emptying or decrease digestive enzyme access, organic acids and their salts to slow down gastric emptying, or anti-nutritional agents that inhibit digestion of starch, and other low-glycemic carbohydrates. Most importantly, human trials must show what levels of such carbohydrate-based ingredients or foods are needed to elicit a positive physiological or metabolic response. Food form will continue to be a major issue in the development of slow digesting cereal foods. Highly organized, dense food forms impede starch digestion and, thereby lower the glycemic response of starchy foods. Besides pasta, whole kernel foods, wherein the cellular layers surrounding the starch granules are intact, also present an example of an organized food form with low GI and probable slow digestion property.