Effect of Steam Explosion Treatment on Starch Molecular Structure of Indica Rice Starch

The influences of steam exploded pressure, retained time, and sample moisture content on starch molecular structure of indica rice starch treated with steam explosion were analyzed by gel chromatography(GPC), ultraviolet–visible spectroscopy(UV), and Fourier transform infrared spectroscopy(FT-IR). The results showed that, with the increase of steam exploded pressure, retained time, and sample moisture content, molecular weight of indica rice starch were decreased, and the proportion of starch short chain pieces was increased. In addition, the intermediate absorption peak gradually disappeared, and the degree of polymerization of indica rice starch chains was decreased. The maximum absorption wavelength of UV spectrum showed a blue shift. As the intensity of steam explosion treatment increased, the intensity of aldehyde group absorption peak at 1650 cm-1 in the infrared absorption spectrogram increased, and starch infrared crystallization index(ICI) increased. Steam explosion technology effectively degraded the polymerization degree of indica rice starch chains and increased the crystallinity starch granule.