Production of Esterified Starches with Increased Resistant Starch Content by an α-Hydroxy Acid-Catalyzed Route

Resistant starch (RS) refers to the portion of starch that is not broken down by human enzymes in the small intestine, and thus reaches the large bowel of healthy individuals. In the large bowel RS is fermented by colonic microflora producing short chain fatty acids (SCFA) - predominantly acetate, propionate, and butyrate - that are known to contribute substantially to large bowel health. Currently, there is an increasing interest in obtaining RS by esterification of starch with target SCFA, due to its capacity to deliver significant quantities of the particular esterified SCFA to the colon. In the current contribution an -hydroxy acid-catalyzed methodology, which has recently proven useful for esterifying starch, was used to produce acetylated, propionylated, and butyrylated corn starch samples with varying degree of substitution (DS) (0.05-0.75). Results showed the suitability of the route to produce the RS4 starch type, with RS contents that increased with DS as a consequence of a larger steric hindrance effect caused by a higher number of ester groups introduced. Data also indicated that the DS conferred to starch was the key factor conditioning its resistance, whereas RS content showed to be independent of the resulting esterified starch structure and the type of ester group introduced.