Application Studies On The Evaluation Of Rice Eating Quality With Mixolab

The Mixolab is a new instrument for detecting cereal quality developed by Chopin. In order to explore new approaches and new characteristic index for evaluating rice eating quality, the feasibility of the Mixolab used for rice eating quality was investigated in the paper. On the basis of stability of the key parameters of Mixolab in the process of detecting rice quality, the paper attempeted to seek the characterization point of rice quality, and the correlections among the Mixolab characteristic values and physio-chemical index of rice eating qualities, such as amylose content, gel consistency, gelatinization temperature and protein content. In the end, the correlations among the Mixolab characteristic values and rice eating qualities were studied, with an aim to account for whether Mixolab can be used to evalute rice eating quality. The results were as follows:(1) In order to study the effect of the rice flour distribution, water absorption and mixing speeds on the rice eating quality detection with Mixolab, and seek the best condition for the rice eating qualities detecting with Mixolab, four rice sample with different amylose content, such as Guodao1 Guodao8, Changgengdao and glutinous rice-Y4 were used as materials in the experiment. The results showed that the three factors significantly affected the test datum, and the 0.8 mm of mesh size of screen, 140 rpm of rotate speed and 60% of water absorption were optimum condition for the rice eating qualities detection with Mixolab in the experiment, which could meet the requirements with the standard deviation lower than 10%.(2)Adding the additives, such as rice bran, defatted rice bran and deproteinizated rice bran to the rice flour had significant effects on the Mmixolab graph, and the Mixolab maps of rice flour between adding rice bran and defatted rice bran were similar. The Mixolab charateristic values were significantly positively corrected with the starch content, especially on the C1, C2, C3, C4 ,C5 andβ, with correlation coefficients 0.4684, 0.6987, 0.9119, 0.8784, 0.8810 and 0.8087, respetively, while they were markedly negatively correlated with the protein content, with correlation coefficients -0.5162, -0.5662,-0.8486 -0.8636, -0.8565 and -0.8376, repectively. Meanwhile,γwas markedly negatively correlated with starh content, while it was markedly positively correlated with protein content. Fat was siginficantly negatively correlated with C1, C2 andβ, while fibre was siginficantly negatively correlated with C3, C4 ,C5,βbutγ. It can be prelininary inferred that C1, C3, C4, C5,β,γstand for determin absorption, measures starch gelatinization, measures the stability of the hot-formed gel, mearsures starch retrogradation during the cooling period, starching speed, and enzymatic degradation speed, respectively.(3)41 rice varieties with different amylose content were used to study the correlation between the physio-chemical parameters of rice and the Mixolab graph. The results indicated that the rice gel consistency, amylose content, gelatinization temperature and protein content were significantly correlated with certain characteristic values of the Mixolab graph, and the gel consistency was significantly positively correlated with C1, C2 and C3-C4, while it was significantly negatively correlated with C4 andγ. There were significant correlations between the amylose content and C3, C4 and C5, but amylose content was significantly negatively correlated with C1. The gelatinization temperature was also significantly positively correlated with C1, C2, C3, C5 and C3-C4, but it was significantly negatively correlated withγ. Contrary to the gelatinization temperature, the protein content was significantly negatively correlated with the C1, C3, C5, C3-C4 andβ, while it was positively correlated withγ. In addition, a correlation cluster analysis indicated that there were more significant corrections between the Mioxlab graph characteristic values and physio-chemical parameters of indica rice than with the other rice types in the experiment.(4) 41 different rice varieties with different amylose content were also used to study on the relation between the rice eating quality and Mixolab graph. And the correlation analysis demonstated that C1, C3-C4 andγwere significantly correlated with the rice eating quality, with correlation coefficients 0.7513, 0.7518 and -0.7581, respectively, which can be used as characteristic points of rice eating quality and be suitable for building regression model for estimating the rice eating quality. In sum, the Mixolab was more suitable for estimating the eating qualities of indica rice.To sum up, by choosing appropriate parameters, Mixolab graph not only has good stability, but also its characteristic values can reflect physio-chemical parameters and eating quality of rice. Mixolab can be used to detecte the eating quality of rice.