Effects of Different Storage Environment and Time on Rice Quality

Abstract

In order to study the quality variation of Longjing 31 rice in ordinary and negative-pressed rice bucket put in the environment with high temperature and high humidity and room temperature during storage, rice color parameters, fatty acid value, taste value, amylose content, protein content, fatty acid compositions, gelatinization characteristics of rice flour were measured. Two dimensions of rice quality under storage conditions and storage time were analyzed by radar analysis. It showed that high temperature, high humidity and storage time could step up the deterioration of rice quality. Different storage conditions and time had significant effects on peak (1 991~2 859 cP), final (2 650~3 334 cP) and trough viscosity (1 459~2 182 cP), fatty acid value (2.74~32.58 mg/100 g), oleic (1.12~1.81 mg/g) and linoleic acid (2.68~3.53 mg/g), as well as the taste value (68.72~80.30 score) (P < 0.05). The radar map analysis showed that quality deterioration indexes of rice stored in high temperature and high humidity ordinary rice bucket were mainly reflected in fatty acid value, oleic acid and linoleic acid; quality deterioration indexes of rice stored in high temperature and high humidity negative-pressed rice bucket were mainly reflected in peak viscosity and final viscosity; quality deterioration indexes of rice stored in common rice bucket at room temperature and negative-pressed rice bucket at room temperature were mainly reflected in peak viscosity and trough viscosity, respectively. For different storage time, the peak and trough viscosity showed a trend of first increase and second decrease, the fatty acid value increased continually, the oleic acid and linoleic acid contents sharply decreased after storage for a certain time, and the taste value gradually decreased. To sum up, it showed that the negative-pressed rice bucket could better maintain the rice quality for short time (15 days) storage, and there were no significant differences between ordinary and negative-pressed rice buckets for long periods (15 days or more) of rice storage.

Keywords

• milled rice
• storage
• taste value
• fatty acid
• gelatinization characteristic