Preparation and physical characteristics of slowly digesting modified food starches

Abstract

Starches were chemically modified with the goal of making modified food starch products with high contents of slowly digestible starch (SDS). Digestibility and physical properties of the products were measured. For waxy corn starch, combinations of crosslinking (CL) followed by stabilization via hydroxypropylation (HP) or acetylation (AC) produced more SDS than did crosslinking alone; CL-HP produced the highest content of slowly digestible starch (SDS, ∼21%), while CL-AC produced the highest content of resistant starch (RS, ∼24%). CL-HP (prepared without salt in the reaction mixture) and hydroxypropylation (with NaCl in the reaction mixture) followed by crosslinking (HP-CL) had similar SDS contents, but HP-CL had a higher RS content, indicating that the presence of salt as well as the order of modification could affect digestibility of the modified starch. Esterification with 2-octen-1-ylsuccinic anhydride (OSA) was the most effective of the modifications used for increasing both SDS and RS. Dry heating (130 °C) of OSA waxy corn starch increased the SDS content and decreased RS content. OSA starches had lower pasting temperatures and higher peak viscosities than their native counterparts. Dry heating of OSA starches resulted in even lower pasting temperatures. Peak viscosities were higher for heated OSA waxy corn and tapioca starches, but lower for heated OSA normal corn and potato starches as compared to unheated octenylsuccinylated starches. To, Tp, and gelatinization enthalpy (ΔH) decreased in the order native waxy corn starch > OSA waxy corn starch > heated OSA waxy corn starch. Using the combination of esterification with OSA followed by dry heating the following amounts of SDS were produced: from waxy corn starch, 47%; from normal corn starch, 38%; from tapioca starch, 46%; from potato starch, 33%.