Effect Of Storage Temperature And Moisture Content On Rice Quality

This paper selected a kind of japonica rice and indica rice,both of which were of several different levels of moisture content, and stored at different temperatures. It is primarily studied in this paper the difference of rice quality induced by different storage conditions, the suitable storage condition for rice of higher moisture content, which could maintain rice quality without too much cost. The results showed: After a 12-month storage period, rice quality indexes of different storage temperature and moisture content have different changes. Rice stored at room temperature, which experienced a summer heat period, have larger changes in various quality indexes than rice stored at 15℃and 20℃. The changes of various indicators of higher moisture content rice stored at 15℃and 20℃is larger than safety moisture content rice stored at the same temperature, but the difference is small, and the rice could still be stored after 12 months. Stored at a temperature of 20℃, during 12 months or even longer storage period, higher moisture content rice could effectively delay its aging speed to achieve its safety storage without too much cost. During rice storage process, its light transmittance difference prensented a downward trend, but fluctuated without rules. So, light transmittance difference might be used for qualitative analysis, but not suitable for quantitative analysis. In rice storage process, its viscosity decreased, hardness increased, viscosity / hardness also decreased. It was showed in the paper, the changes of rice texture characteristics were not isolated, there are significantly correlations between texture characteristics and proteins, cell wall, lipids and other chemical compositions. And the correlations between these indexes of indica were larger than japonica. The microstructure study of rice suggested that storage temperature and rice moisture content affected the membrane change of rice starch cell surface, the higher the moisture content or the storage temperature was, the more the compound starch granules was, and the thinner the starch cell surface membrane was. After a 12-month storage, starch granules developed from single particle to compound, the degree of capsule wrapped increased, bare degree decreased, cracks began to appear between the starch cells. High moisture content rice changed more than rice of safety moisture in microstructure, and rice stored in higher temperature changed more too, but rice of differen moisture content and stored in different temperature had similar changing trends in microstructure.