Physicochemical properties of high-amylose rice starches during kernel development

In this paper, endosperm starches were isolated from a high-amylose transgenic rice line (TRS) and its wild type rice Teqing (TQ) kernels at different developmental stages. TQ and TRS starches showed similar amylose contents and shapes at early developmental stage, then the amylose content increased with kernel development. The rate of increase in amylose content was much faster in TRS starches than that in TQ starches. TRS starches showed heterogenous granules at the middle and late developmental stages. TQ starch crystallinity remained A-type, but TRS starch crystallinity changed from A- to C- via CA-type. TRS starches showed higher gelatinization temperatures, lower gelatinization enthalpies, lower swelling powers, and lower hydrolysis rates at middle and late developmental stages compared with TQ starches. The amylose content had a significantly negative correlation with crystallinity, gelatinization enthalpy, swelling power, enzyme digestibility, and acid hydrolysis.