Characteristics of acetylated starches prepared using starches separated from different rice cultivars

The physico-chemical properties of acetylated starches from different rice cultivars were evaluated. The acetylation of starches from different cultivars showed different acetyl (%) and degrees of substitution (DS). The FT-IR spectral analysis confirmed the introduction of acetyl moiety in the acetylated starches through a band at 1730.8 cm−1. The scanning electron microscopy did not show any significant difference between the external morphology of native and acetylated starches. The acetylated rice starches showed slightly higher amylose contents than their native counterparts. Acetylation increased swelling power and solubility and decreased To, Tp, Tc and ΔHgel of all starches. In all starches, acetylation decreased pasting temperatures, but increased peak viscosities. Acetylation brought greatest change in To of the starch showing highest DS and least in the starch showing lowest DS. Acetylation caused weakening of the starch gels, which was observed to be dependent on degrees of substitution. Starch gels stored at 4 °C showed a significant decrease in syneresis (%) upon acetylation. The effectiveness of acetylation in reducing retrogradation was more evident from syneresis data than from setback viscosities observed by RVA.