Model for evaluating paddy rice quality based on principal component analysis of its mechanical indexes

In order to overcome every malpractice of the previous methods for appraising paddy rice quality, based on paddy rice mechanics rheological indexes, this paper, embarking from the sample correlation matrix, analyzes fourteen main mechanical characters of seven varieties of paddy rice by the principal component analysis method. According to more than 91.1% of the cumulative variance proportion, three new independent indexes were established，which were related to the quality of paddy rice. Principal component z1, rigidity factor; principal component z2, elasticity factor; principal component z3, viscidity factor, the principal component values of varieties were obtained. Paddy rice could be classified depending on the principal component values, and the results were similar to the classified results depending on taste quality. The results of correlation analysis between the principal component and the taste quality of paddy rice show that, PRIN1 has a closely positive correlation with the taste quality, and PRIN2 has a positive correlation with the taste quality. Regression equation between taste quality and principal component was developed by using Stepwise Regression, which could be used to predict and evaluate quality of paddy rice.