Correlation Factor Analysis Of The Differences In Starch Digestibility Of Rice Under Different Cooking Conditions

In this paper, indica hybrid rice, japonica rice and waxy rice with different amylose content were studies. First of all, cooked indica hybrid rice as the research object, the comparative studies the differences of in vitro starch digestion protocol; Secondly, the functional and structural characterization of the three kinds of rice starch were carried out.Finally, the effect of different processing conditions on the in vitro digestibility of starch in raw or cooked rice flour and cooked rice was studied. The results are as follows:Through the comparison of different digestion protocol, we found that regardless of the cooked indica rice or starch gels digested by the simulated gastro digestion and intestinal fluid in adding amylase and protease will cause the increase of starch digestion.Therefore, in order to more close to the human digestive environment and more accurate detection of in vitro starch digestibility, simulated gastro-intestinal digestion and the addition of amylase and protease in small intestinal digestion is necessary.Through the comprehensive characterization of the three kinds of rice varieties, it can be concluded that indica hybrid starch (IHS) had the highest proportion of long branch chains and the lowest proportion of short branch chain, whereas the opposite results were observed for japonica starch (JS). Relative crystallinity ranging from 33.4 %for JS to 39.4 % for waxy starch (WS). Significant differences were observed in lamellar distance and short-range molecular order. The lower pasting viscosity of WS was attributed to the formation of less rigid swollen granules at a concentrated regime. WS showed higher in vitro digestibility compared with IS and JS. Our results show that the multi-scale structure of starch granules determines the functional properties of starch.By evaluating the in vitro starch digestibility of raw and cooked rice flour by different processing methods, it can be concluded that the overall paste viscosities of cooked IHF and JF were lower than those of their corresponding raw flours. However,cooked WF showed much higher paste viscosities than raw flours. Cooking increased greatly the rate and extent of starch digestion of IHF and JF, but had a small effect on WF.There were small differences in the rate of starch digestion and estimated glycemic index of rice after cooking under various conditions. The present study demonstrated that cooking methods had little effect on in vitro starch digestibility of cooked rice flour.For cooked rice, at the same ratio of rice to water, the in vitro starch digestion of rice with pre-soaked cooking was higher than that of un-soaked cooking except for WR-P-1:1.At different the ratio of rice to water, starch digestibility of cooked rice no increase with increasing the ratio of rice to water. The RS content of indica hybrid rice (IHR) was as high as 19 % compared with japonica rice (JR) and waxy rice (WR) at atmospheric pressure cooking, the RS content of WR was as high as 8 % compared with IHR and JR at pressure cooking. The results showed that the texture properties and cooking methods affected the in vitro starch digestibility of rice. Through this research, we can provide the appropriate rice cooking way to meet the needs of different people, which was of important theoretical and practical significance.