Resistant starch in vitro and in vivo : factors determining yield, structure and physiological relevance

Knowledge of the food processing methods and conditions as well as the underlying mechanism that leads to the formation of resistant starch (RS) in foods is of great importance for nutritionists as well as food industries, since it offers the possibility of increasing the RS content in processed foods. RS is normally defined as that portion of dietary starch that escapes digestion in the small intestine of a healthy human. The amount of RS in a given food is determined by many different factors. Food form and structure, botanical source of the starch and its amylose content, other dietary constituents, notably protein and fat, the presence of a-amylase inhibitors and other antinutrients, the methods used to manufacture and store foods, and culinary practices all directly influence starch digestibility in the gut. Although most of the attention that RS has attracted from health professionals relates to its positive effects on bowel health, there is theoretical and mounting experimental evidence that RS has beneficial physiological properties, which extend beyond the gastrointestinal tract. Food scientists have attempted to enhance the level of enzyme-resistant retrograded starch in the diet. Numerous studies are carried out to characterize the molecular and microstructural organization of RS fractions, aiming at unraveling the mechanisms of amylolysis resistance.