Effect Of Endosperm Lipid On Rice Quality And Digestibility

Lipid is an important component of rice,classified as starch lipids and non-starch lipids,which not only has unique nutritional value,but also has significant influences on rice quality,particularly on the functional characteristics of starch.Clarifying the mechanism of lipid affecting rice quality will promote the improvement of rice quality and the development of functional rice.In this study,four rice mutants with different lipid content and their parent were used to analyze lipid content and composition and to investigate the influences of endosperm lipid on rice quality and digestibility.This study will provide some scientific bases for improving rice quality and functional rice breeding through exploring the optimal lipid content and composition in rice endosperm.The main results are as follows:1)The lipid content in parent R7954 is only 0.61%,while the lipid in high lipid mutant increased greatly,reached up to 2.52%.In R7954 and low lipid mutant GZ93,endosperm lipid is majorly starch lipid,while in high lipid mutant,the ratio of nonstarch lipid to total lipid is higher.Non-starch lipid contains oleic acid,linoleic acid,palmitic acid,aslo few myristic acid and arachidonic acid,among which unsaturated fatty acids are in a higher proportion.Starch lipid contains myristic acid,palmitic acid,stearic acid,oleic acid,linoleic acid.The unsaturated fatty acid i.e.linoleic acid increased greatly in high lipid mutant;2)Rice endosperm lipid affects the physicochemical properties of starch thorough forming amylose-lipid complex with amylose,while the influences depend on rice cultivars.After defatted treatment,AAC was increased in all rice;high lipid mutants starch showed non-typical V-type crystallinity,while after defat,some typical diffraction peaks of A-type crystal appeared;After removal the endosperm lipid,GT and ?H of R7954 and GZ93 were decreased,GT and ?H of high lipid mutants starch were increased,?H of amylose-lipid complex decreased.After remove starch lipid,GC increased and the viscosity decrease in R7954 and GZ93,the viscosity,gel hardness(HD),adhesion(COH)and chewiness(CH)were increased in high lipid mutants;3)Rice endosperm lipid formed amylose-lipid complex with amylose,affects the digestibility of starch,having.The RS content of rice was significantly correlated with the lipid content.After defatted treatment,starch hydrolysis rate were increased,and the presence of lipids can improve the resistant digestibility of starch.