Physical And Chemical Foundation For Cooking And Eating Quality Of Japonica Rice

Rice is a stable food for more than two thirds of population in China where is the first rice production and consumption around the world.With the rapid development of economy and society,japonica rice was popular as its high quality.Improving rice quality,developing new estimated criteria of rice quality,and meeting the needs of consumer,is one of the most urgent tasks faced with by rice breeders at present.Rice quality including milling quality,appearance quality,cooking and eating quality and nutritional quality,in addition,cooking and eating quality is the main factor which affect consumer's desire,is also the focus and goal of researchers.Cooking and eating quality traits are complex and estimated methods are diversef however,none can evaluate rapidly and accurately the eating quality.In this study,twelve rice cultivars grown in Jiangsu province,twelve mutants mutagenized by Wuyujing 3 and a indica-japonica hybrid rice fe"Yongyou 1540" were used as materials,yield traits,appearance quality,milling quality,cooking and eating quality and nutritional quality were determined by analysis of physical and chemical property,instrumental analysis and artificial sensory evaluation,we investigated the relationship between eating quality and agronomic traits,milling quality,appearance quality,biochemical basis and physical characteristics,respectively.We compared the advantage or disadvantage of different evaluation methods,with the aims to provide a theoretical basis for grain eating quality evaluation and improvement.The main conclusions were as follows:(1)Genotypic differences in rice quality indicators among 25 materials were detected.For yield components,the coefficient of variation(CV)of grain number per panicle was the highest value while that of seed setting rate was the lowest.In terms of milling quality and appearance quality,chalkiness showed the largest CV whereas milling quality presented the smallest one.On biochemical components,the CV of each amino acids were similar,crude fat content exhibited the largest value of CV,followed by albumin and globulin,finally starch components.In rapid visco analyser(RVA)parameters.setback viscosity(SBV)presented the largest CV but the opposite of that of peak time(PT).Enthalpy of DSC showed a maximum of CV while temperature with a minimum.On grain texture characteristic,chewiness,hardness and stickiness tested by a texture analyzer showed the highest CV.Protein content tested by a taste analyzer showed the largest CV.All CV of sensory properties indicators were higher.with the highest for hardness.In present study.most materials are small panicle type with grains being round.higher chalkiness grade(grade 3-4),low amylose content.low protein content.Marked differences existed in chalkiness,SBV,artificial sensory evaluation.(2)Correlation analysis between eating quality and other quality and agronomic traits were performed.The results showed that eating quality had a positive correlation with panicle numbers whereas a negative correlation with grain number per panicle,suggesting that japonica rice with small panicle tend to have better eating quality.Both brown rice rate and chalkiness showed positive correlations with eating quality,which indicated that chalkiness has a beneficial influence on eating quality.Potassium was content negatively correlated with the integrated value of rice taste.Water content affected the grain color and luster.Crude protein and fat contents showed a negative correlation with eating quality,especially for prolamin.which imply that low protein content can improve eating quality.Starch component show little effect on eating quality.In terms of physical characteristics,integrity and hardness of grain were significantly negatively correlated with breakdown.SBV was positively correlated with hardness.Both starch gelatinization temperature and enthalpy showed a significant negative correlation with the integrated value of rice taste.(3)Advantages or disadvantage of different sensory panels were analysed,including texture analyzer.taste analyzer and sensory panel.Comparison the taste analyzer with sensory panel,besides protein and water content showed significant positive correlations with the integrated value of rice taste while other indicators were not significant by a taste analyzer,indicating that taste analyzer still can not take place of eating sensory evaluation.Comparison between the texture analyzer with sensory panel showed no significant correlations.Indicators of artificial sensory evaluation existed highly correlation.Stickiness significantly negatively related to all indicators except for color.Aroma,luster,integrity,flexibility,hardness showed significant positive correlations with the integrated value of rice taste.Our study showed the weakness of instrument analysis for eating quality.suggesting the necessity of sensory panel for eating quality evaluation.