Optical Sum Frequency Generation Spectroscopy of Cracked Non-Glutinous Rice (<i>Oryza sativa</i> L.) Kernels

Abstract

In order to study the correlation between the cracking of rice ( Oryza sativa L.) kernels and the molecular structure of the amylopectin in them, we attempted optical sum frequency generation (SFG) spectroscopy in the C-H stretching vibration region for normal and cracked japonica non-glutinous rice kernels. The samples were Koshihikari and Nipponbare. In Nipponbare, the width of the SFG spectrum peak at 2915 cm - 1 of the cracked rice kernels was broader than that of the normal ones, while for Koshihikari there was no clear difference. The width of the 2915 cm - 1 peak is suggested to originate from the variety of the higher-order structure of the saccharide chains in amylopectin. Although this is a tentative result, this method is shown to have a potential of serving for preventing the cracking of the rice kernels.