Stability Study Of Controlled Atmosphere Storage With N₂on Japonica Rice And Its Unsealed After The Storage

The quality change rule of japonica rice which was stored at different temperatures （20,25,30,35℃） under controlled atomosphere storage with N₂（nitrogen gas concentration morethan98%） and conventional storage during the storage life of120days and removedcontrolled atomosphere storage was studied in this paper.The results showed:The germination rate,viability, the catalase activity in japonica rice under controlledatomosphere storage with N₂and conventional storage all showed a degressive trend withthe increase of storage temperature and time;while fatty acids,conductivity,malondialdehyde content were on the rise, whole refined rice rate and cookingquality（general scores of sensory evaluation）, viscosity and so on decreased,but pastingproperties（peak viscosity, minium viscosity and final viscosity）,hardness,elasticity andcolour in japonica rice all gradually increased.The effect of the two storage ways on quality with the storage time at lowtemperatures（25℃and30℃） was not big and it is beneficial to keep grain quality, however,the quality change of japonica rice speeded up at high temperatures（30℃and35℃）,especially at35℃,the change became more obvious and this is bad for the storage ofjaponica rice. The germination rate and viability of japonica rice under controlledatomosphere storage with N₂were not so good as conventional storage,the case on thecondition of30℃was specially clear, all these indicated the state of lack of oxygen washarmful to maintain the seed quality of japonica rice, yet the other quality indexes showedbetter under controlled atomosphere storage with N₂and this storage way did release theinfluence of high temperature on quality to some degrees.During the time when the japonica rice was removed and storaged as a conventional way,the germination rate, viability, the catalase activity and whole refined rice rate continued tobring down with the increase of storage temperature and time, while the fattyacids,conductivity, pasting properties and colour had an upward trend; peak viscosity,minimum viscosity and final viscosity of japonica rice all had an upward trend with thestorage time, especially for the high temperature of35℃,the increase showed most clearly.This manifested the quality of japonica rice after removed the controlled would still continuethe precious change trend, and the higher the temperature was, the bigger the change occurs.Therefore, controlled atomosphere storage with N₂and low temperature storage werehelpful for japonica rice to refresh its quality, low temperature storage was easy and simpleto handle and low in expense, controlled atomosphere storage with N₂could relieve theinfluence of high temperature on the quality of japonica rice, however, the japonica riceafter removed from controlled atomosphere storage with N₂is not advisable to continue tostore, it was ought to be processed and saled in the market right away, or it could be storedfor short time only under low temperature.