Study On The Relationship Of Japonica Rice Physicochemical Property And Edible Quality

Water, starch and protein are three most important components in japonica rice. Their properties have great influence on the formation of japonica rice edible quality. It is instructive to explore the relationship between physicochemical properties and edible quality for traditional rice and its products’quality evaluation and control.In the experiment, ten japonica rice were taken as materials. Water migration during japonica rice soaking and cooking was determined. Starch properties and gelatinization properties were measured. Albumin, globulin and texture properties were analysed. Edible quality was evaluated; The pearson correlation between starch properties and gelatinization properties were analyzed. Linear regression equations of starch properties and eating quality of cooked rice were established. The main results of this paper are as follows: (1) At first10minutes of cooking, relaxation time T22increased greatly, then T22reduced, while the proton amplitude increased gradually. When cooking was completed, constitution water were the main water statement in cooked rice.(2) There are much difference in amylose content between japonica rice varieties, the difference of chain A and chain B1proportion in amylopectin was big, difference of chain B2and B3+proportion was small; Sensory score ranges from71to92. Liaojing294had minimum hardness(1092g) and maximum viscosity(29.41g*s). Chujing31had maximum hardness(2580g), while Yunjing26had minimum viscosity(10.4g*s).(3) The difference of albumin SDS-PAGE graph between japonica rice varieties was small. Globulin SDS-PAGE graph between japonica rice varieties had some differences. Chujing31, Yunjing26, Guanglingxiangjing and Wuyunjing21had more high molecular weight protein bands in the range of34.75KDa-70.2KDa. High molecular weight subunits led to smaller breakdown value.(4) The negative correlation of AM content and the breakdown value was extremely significant(r=-0.781, p<0.01). The negative correlation of chain B1with peak viscosity and breakdown value was extremely significant(r=-0.878, p<0.01; r=-0.924, p<0.01). The positive correlation of Chain A with peak viscosity and breakdown value was extremely significant(r=0.874, p<0.01; r=0.938, p<0.01). Chain B2had significant crrelation with trough viscosity and breakdown value only, B3+had no significant correlation with gelatinization properties; Breakdown value and hardness were significantly correlated(r=-0.902, p<0.01). Breakdown value had significantly positive correlation with viscosity, springiness and sensory score. Setback value and hardness were significantly correlated(r=0.937, p<0.01). Setback value had significantly negative correlation with viscosity, springiness and sensory score; Linear regression equations of hardness, adhesiveness, springiness, cohesiveness, resilience and sensory score of cooked rice were established by stepwise regression analysis. The regression equations can predict the edible properties of japonica rice. Japonica rice with higher chain A content, lower amylose content, chain B1content and crystallinity had better eating quality.