Resistant starch

Abstract

This simple question belies the underlying complexity of the topic. The concept of resistant starch (RS) first arose due to inconsistencies in the analysis of total dietary fiber (TDF). 1 From the beginning, RS has been troubling to the food analytical chemist. Although dietary fiber is a physiological concept, it has been understood as a physiological concept that would be amenable to chemical analysis because the carbohydrate polymer composition of dietary fiber was understood to be due only to nonstarch polysaccharide (NSP). 2 The idea that only NSPs contributed to fiber was reasonable because the only enzyme available in the small intestine to hydrolyze polysaccharides is α -amylase; thus, NSP cannot be hydrolyzed in the small intestine. Nevertheless, in early in vitro analyses of TDF, the value for a particular sample varied according to the way the sample was treated prior to analysis. As it turned out, the assumption that starch was fully digested in the analytical procedure was faulty, as even a boiling treatment in the presence of heat-stable α -amylase was not sufficient to digest all of the starch in some samples, and the proportion of the undigested starch was affected by prior treatment. Thus, the concept of enzymeresistant starch was born from a problem in the attempted chemical analysis of TDF. Ensuing research showed the RS to be of physiological significance.