Study On The Structure And Properties Of Starch In Japonica Rice And Its Products With Different Amylose Content

Amylose content,as an important index to measure rice quality,is widely used in the breeding of high-quality rice varieties.As the main component of rice endosperm,the content and structure of starch affect the quality and functional characteristics of rice.In this paper,waxy,normal and high amylose japonica rice were selected.The amylose content was less than 0.5%,18.8% and 33.3% respectively.Taking the comparison of structural and functional characteristics between Japonica Rice Starch with 33.3% amylose content and glutinous rice and ordinary japonica rice starch as the starting point,we can fully understand the structure and properties of Japonica Rice Starch with different amylose content,and further explore the cooking characteristics of rice and the structural and functional characteristics of starch in rice products.Structural and functional characteristics of three Japonica rice starches differing in amylose content were investigated using a range of characterization methods.As amylose content increased,the weight-average molecular weight,short-range order,relative crystallinity,and lamellar peak intensity of starch decreased.high-amylose starch contained a lower proportion of A chains than waxy and normal starches.high-amylose starch displayed a C-type crystalline structure,different from the A-type crystalline structure of waxy and normal starches.Compared with waxy and normal starches,high-amylose starch exhibited higher granule size(volume-average diameter),pasting temperature and higher resistant starch content,but lower peak viscosity,breakdown viscosity,swelling power,and rapidly digestible starch content.The cooking properties of Japonica rice with different amylose contents were investigated.waxy,normal,and high-amylose Japonica rice were cooked at normal pressure and evaluated for water absorption,volume expansion,molecular mobility,microstructure,crystalline structure,and starch digestibility.The results showed that high-amylose rice had lower peak viscosity but higher pasting temperature and final viscosity than waxy and normal rice.After cooking,high-amylose rice showed slightly higher water absorption ratio but lower volume expansion ratio than the other two rice varieties.Water was more evenly distributed in cooked waxy and normal rice than in cooked high-amylose rice.After cooking,starch in waxy and normal rice kernels almost lost the entire crystalline structure,but starch of cooked high-amylose rice still exhibited strong V-type crystallinity.Cooked high-amylose rice contained higher content of resistant starch than cooked rice of other two varieties.The structural and functional properties of starch in Yin rice,rice tea and rice flower were compared.The results showed that there were significant differences in water absorption and expansion between Yin rice porridge and rice tea,and high amylose had the lowest water absorption and expansion.waxy in Yin rice porridge,rice tea and rice flower has no obvious diffraction characteristic peak.Compared with normal,the position of high amylose diffraction peak in the three rice products is basically the same,the intensity increases,and the crystal structure is basically not damaged.The final viscosity and recovery value decreased with the increase of amylose content.The RDS content of high amylose in rice flower was lower than that of Yin rice and rice tea,and the contents of SDS and RS were higher than that of other rice products.