Research advances on structural characterization of resistant starch and its structure-physiological function relationship: A review.

Resistant starch (RS) is defined as the fraction of starch that escapes digestion in the small intestine due to either difficult enzyme/starch contact or to the strength of the crystalline regions formed both in native starch and in those retrograded starch. RS occurs naturally in some foods, and some may be generated in others as the results of several processing conditions. Varieties of techniques have been employed to obtain structural characteristics of RS such as their crystallinity, structural order, chain-length distribution and conformation, helicity, and double-helical structures. These structures play an important role in determining the physiological properties of RS such as their prebiotic and hypoglycaemic properties. However, such topic on structural characterization of RS and their structure-physiological function relationship have not been reviewed in previous literatures. Therefore, this review focuses on the past and current achievements of research on structural characterizations of a range of RS prepared from different sources of native starches as a result of a variety of processing conditions. The potential relationships between the structure and the physiological properties of RS, which is of paramount importance for the furtherance understanding and application of RS, are also reviewed in this study.