Acetylation of rice starch in an aqueous medium for use in food

Abstract

The degree of acetylation controls the use of starch acetate, since the FDA (Food and Drug Administration USA) recommends an acetyl groups' percentage below 2.5 g/100g for a food application. The objective of this work was to evaluate the effects of the acetic anhydride concentration, in an aqueous solution, on the degree of acetylation, in physical, thermal, pasting and morphological properties, and enzymatic susceptibility on rice starch acetylated with the acetyl groups' percentage up to 2.5 g/100g. The rice starch was acetylated using different concentrations of acetic anhydride (5 g/100g, 10 g/100g and 20 g/100g, starch db). Acetylation increased the peak viscosity, breakdown, final viscosity, retrogradation and pasting temperature and reduced the hardness of the gels, as well as their adhesiveness and gumminess; however this did not affect the morphology and susceptibility to hydrolysis by the α-amylase of the starch. The acetylated starches using 10 and 20 g/100g acetic anhydride showed lower swelling power and solubility compared to native starch.