Effects of Some Physicochemical Properties of Paddy Rice Varieties on Puffing Qualities by Microwave “ORIGINAL”

Abstract

Ten paddy rice varieties, both waxy and non-waxy paddy rice, which are cultivated in the northern and northeastern region of Thailand, were selected to study the effects of some physicochemical properties on the qualities of puffing rice (puffed yield, expansion volume, expansion ratio and bulk density) using microwaves at a frequency of 2450MHz and power at 800 watts. It was found that the amylose content (range 5.58-21.24%) was strongly negatively correlated with all qualities of puffed rice: puffed yield (r=-0.95**), expansion volume (r=-0.82**), expansion ratio (r=-0.79**) and bulk density (r=-0.78**). The starting time of puffing negatively correlated with puffed yield (r=-0.67*), while tightness of husk (lemma-palea) interlocking, thickness of ventral region layer, husk content, width and length of brown rice were unrelated to puffed rice quality. Amylose content could explain the puffing qualities of puffing rice. The coefficient of determination (R2), for the linear correlation with amylose content with regard to the quality of rice puffing for puffed yield, expansion volume, expansion ratio and bulk density was 0.91, 0.67, 0.62 and 0.61, respectively. Paddy rice with suitable physicochemical properties for puffing by microwave heating has low amylose, a thin ventral region and a puffing time that starts quickly and continues, as exhibited in rice varieties RD 6, RD 10 and NSPT.