| Paddy is one of Chinese major grains and its yield and quality are very essential. 40% of the annual output is for storage. But during storage, germination rate decline, aging and other quality deterioration problems often arise, which leads to the loss of 100 billion kilograms of paddy per year. In recent years, the government has used high technology to push agricultural development, which makes the paddy storage techniques step forward with less losses. However, we haven’t achieved a breakthrough for some key technologies. The fundamental reason is that the basic research for grain storage is lagging behind. With the development of high throughput technologies, like genomics and proteomics, researchers can explore macromolecules changes in cells or tissues from the biological point of view. Proteomics can clearly identify the protein change in foods and reveal the interactions between proteins or protein and other components after food materials are processed. This provides a new method for the study of paddy storage technology. Because of the new method, people can explore the change of protein contents and kinds in grain by proteomics technology at molecular lever in order to infer the structural change and interactions between protein and other components. Then it can be known about how these changes affect the quality of paddy during storage to provide theoretical support for improving grain storage techniques.In this thesis, physical and chemical indicators of paddy in different temperature and time under conventional and CO2 controlled atmosphere storage were studied, including fatty acid value, moisture, texture characteristics, a-amylase and lipoxygenase activity. Through differential proteomics analysis, the molecular mechanisms for aging of paddy during storage were stated in this thesis at proteome lever. And the rules and effects of interactions between protein and other nutrients were analyzed.It was found that fatty acid value of paddy during storage increased gradually and with the temperature being higher, the rise was greater in both conventional group and controlled atmosphere group. What’s more, CO2 can play a delayed effect of fatty acid value increasing. Judging from the content of water, bound water decreased and loosely bound water increased. And with the temperature becoming higher, the change was faster. Besides, CO2 exerted the best effect for paddy stored in 37℃. Also, rice texture characteristics presented regular patterns with time. Rice hardness and adhesiveness decreased, gumminess increased, springiness and resilience decreased. Overall, CO2 worked litter for paddy stored in 4℃, but exerted obvious effect for paddy stored in 37℃. In addition, rice hardness and gumminess data showed that CO2 worked the most efficiently in 25 ℃. About enzyme activity, a-amylase declined with storage time. And with the temperature becoming higher, the decline was faster. Meanwhile, lipoxygenase activity gradually increased and CO2 played a nice role in defer the change.Through studying the proteome of the Od,25℃ 90d,25℃+CO2 90d and 37℃ 90d paddy sample, it was found that proteins of larger molecular weight showed a large number of downregulation, meantime, upregulation proteins turned out to be proteins of low molecular weight. The results showed that the metabolic reactions were mainly catabolism for paddy during storage. Compared to the 25 ℃ 90d paddy, 37℃ 90d paddy proteins changed more which meant with the temperature becoming higher, the aging was faster. Results in contrast to 25℃ 90d,25℃+CO2 90d paddy sample had less catabolic reactions. And it was good for quality maintaining. Moreover, these proteins change also connected with other nutrients or paddy quality. For example, the decline of bound water and enzyme catalysis might lead to disulfide bonds between proteins. Then the increase of disulfide bonds could worsen the taste of rice. And the downregulation of dihydrolipoyl dehydrogenase also made paddy quality rather worse. |
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