Study On The Relationship Between Paddy Storage Quality And Coupling Factors

Paddy is the largest crop in China.Nearly two-thirds of China take rice as their staple food.In order to ensure food security and meet the growing needs of people for a better life,preserving paddy quality and freshness is an urgent need of paddy storage.It can increase effective grain supply under the new situation.The current research on the storage quality of rice mainly focuses on the law with a single factor（such as storage temperature）;the actual grain storage quality is the result of the coupling effect of multiple factors such as storage time,storage temperature,and storage humidity.Therefore,this article introduces two coupling factors of accumulated temperature and accumulated humidity and explores their relationship with the storage quality of paddy.In this paper,Jilin japonica paddy with different initial moisture content is the research object.The moisture content,storage quality index and physiological activity index of the paddy during the 60-day storage of different storage conditions were measured.The results showed that the moisture content of paddy depended on the storage relative humidity at constant storage temperature;the storage quality and physiological activity indexes were significantly correlated with storage time and storage humidity;and the degree of deterioration of paddy quality was positively correlated with storage time at higher relative humidity.Based on the principal component analysis,browning rate,chalkiness,fatty acid value and MDA content were identified as the main indicators of storage quality.And germination rate,LOX3enzyme activity and POD enzyme activity were the main indicators for physiological activity of paddy.During paddy storage,changes in its quality are closely related to lipid metabolism.Therefore,UHPLC-TOF-MS/MS and GC-MS were used for researching non-targeted lipidomics and targeted medium and long-chain fatty acid.And the content of lipid composition and medium and long-chain fatty acids were measured after 0 days,15 days and60 days of storage.When 15 days of storage,the antioxidant system represented by catalase and peroxidase in paddy works to resist the influence of the external high temperature and high humidity environment and the internal lipid peroxidation.However the change of lipids mainly manifested as the decrease of DG content and the increase of PA content.It is speculated that glycerides represented by DG are hydrolyzed for energy,and the content reduced.As cell membrane component and information transmission molecule,the increase of PA content reflects the changes in paddy cell membrane function and the response to external stimuli.After 60 days of storage,the content of TG and DG increased,while the content of PA carrying ultra-long-chain unsaturated fatty acids decreased.The resason may be the increasing of the stratum corneum content in order to resist the high temperature environment.The test of medium and long-chain fatty acids found that the content of saturated fatty acids in paddy increased,the content of polyunsaturated fatty acids decreased,and the content of monounsaturated fatty acids first increased and then decreased.Finally,the concept of accumulated storage temperature and accumulated humidity is introduced.Based on the quality data of paddy,the variation and correlation between paddy quality and its influencing factors during storage were analyzed to determine representative quality indicators and corresponding RH₀.The change model of the storage quality of paddy and its influencing factors was established.It is contributed to shorten judge period and improve judge accuracy of paady storage quality.Therefore it can take scientific basis for the goal of keeping the quality and freshness of paddy during storage.