Function-structure relationships of acetylated pea starches

Cowpea, chickpea and yellow pea starches were studied and the results showed that their properties were strongly related to the chemical fine structures of the starches. Furthermore, granular starches were modified using two types of chemical acetylation reagents and then separated into different size fractions. The amount of introduced acetyl groups was found to depend on the size of the granules for the reaction with rapidly reacting reagent acetic acid anhydride, whereas the amount of introduced acetyl groups was independent from the granule size for reaction with the slowly reacting reagent vinyl acetate. Modification with the two types of reagents resulted in significant difference in physical properties of the starches. The investigation on the chemical fine structure of modified starches suggested that the distribution of acetyl groups over both the amylose and amylopectin populations of the starches was different, not only at molecular level but also at granular level