Dependence of physiochemical, functional and textural properties of high-resistant starch rice on endogenous nonstarch polysaccharides

To investigate the possibility of improving the quality of rice rich in resistant starch through operation of nonstarch polysaccharides, the high dietary fibre (7.24%) mutant cw and its wild-type R7954 were selected to study the physiochemical characteristics of starch before and after removal of nonstarch polysaccharides. Results showed that hydrolysed or partially hydrolysed nonstarch polysaccharides in cw decreased the resistant starch content significantly, from 15.23% to 10.8%. Nonstarch polysaccharides had significant influences on the gelatinisation temperature, RVA parameters of R7954, but no significant influences on that of cw. For cw, removal of cellulose increased swelling power and adhesiveness, decreased the hardness significantly, from 0.3 to 0.23N, while the resistant starch content was still as high as 13.72% and showed no significant difference from the wild type. This suggests that the influences of nonstarch polysaccharides on starch properties depend both on the type of rice and the nonstarch polysaccharides. Operation on nonstarch polysaccharides for obtaining rice with lower glycemic index is feasible, but operation on nonstarch polysaccharides may also be an alternative way of improving the palatability for rice high in resistant starch.