Study On Paddy Preservation By Controlled Atmosphere Storage With N₂

The paddy rice is one of our country's main grain reserves plants. It is easily infected by insect pest and occur quality deterioration in the preserve process. The refreshment of paddy quality under controlled atmosphere storage with N₂ was studied. Compared with two kinds of rough rice and unpolished rice in conventional storage, the changes of paddy quality for 180 days'storage at different temperatures under controlled atmosphere storage with N₂ were studied.The germination percentage, brown rice rate, the fat acid value, catalase activity, free sulfhydryl group content, conductivity, gelatinization characteristic value were determined at regular time, and the endosperm micro-structure of rough rice (unpolished rice) was observed. The law for quality indicators'changing under controlled atmosphere storage with N₂ was studied. A field experiment on controling atmosphere was made with airbag and nitrogen produced by pressure swing adsorption system, airbag was completely sealed by Dual Slot tube and nylon thin film. The quality vairiation after controlled atmosphere storage with N₂ were studid. Three kind of insect pest of different strain were dealed with different N₂ concentration and lethal effect was studied in different temperature. The results were as follows:As the increasing of the storage time and the temperature, The paddy rice germination percentage, brown rice rate rise, catalase activity, free sulfhydryl group content of controlled atmosphere storage with N₂ and controlled group gradually decreased, and the fat acid value and conductivity increased gradually. The changes of germination percentage, free sulfhydryl group content, fat acid value and conductivity of controlled atmosphere storage with N₂ group were less than controlled group.Fat acid value and conductivity of unpolished rice under controlled atmosphere storage with N₂ gradually increased, but it were less than controlled group. The increasing rates were remarkable in high storage temperature. The increase of paddy fat acid was effectively suppressed under controlled atmosphere storage with N₂ .The change range of rough rice (unpolished rice) dextrinize characteristic value under controlled atmosphere storage with N₂ was less than controlled group. The higher storage temperature, the changes were more remarkable. The micro-structure's change of rough rice (unpolished rice) in controlled atmosphere storage with N₂ was delayed. The starch granules and protein connection level and sequence were holded and the starch granules bareness was reduced.Correlation analysis were used in the quality indicators of storage temperature and storage conditions. The quality indicators were greater influenced in storage temperatures than in storage conditions. The quality indicators under controlled atmosphere storage with N₂ were extremely significant correlated with each other.Paddy quality changes of field trial in controlled atmosphere storage with N₂ were similar to simulation bin, but the changes of core were significantly less than surface.The higher of N₂ concentration, the pest was more quickly skilled. The lethal effect of Tribolium castaneum (Herbst),Cryptolestes ferrugineus(Stephens) and Sitophilus oryzae(Linnaeus) were obvious in 98% of N₂ concentration. When all the insect pest were killed, it was longer time of adjusting to 93% of N₂ concentration than 98% of N₂ concentration.Under the same N₂ concentration, the pest mortality in high temperature were greater than low temperature. The tolerance ability orders of three test insects were as follows, first is Sitophilus oryzae (Linnaeus), second is Cryptolestes ferrugineus (Stephens) and the last is Tribolium castaneum (Herbst). The average tolerance ability of different insect times to the N₂ were the adult stage > the egg stage.