Research On Different Controlled Atmosphere Influencing On Stability And Ediblity Of Rice Quality

Rice is the main food crop in China. There are often some quality changes occurredduring the storage with freshness declining over time, resulting in decreasing of foodvalue and commercial value and losses of enterprises that taking rice as their mainproducts. With the increasing number of nuclear families and the improvement ofliving standards, people’s health awareness has gradually increased; the gunny bagsand other traditional forms of packaging cannot meet people’s demand, while marketdemand for efficient, clean, environmentally friendly small package of rice peoplegrowing high. Therefore, the study on the storage preservation of rice has been paidmuch attention by the food scientists at home and abroad. And rice packagingtechnology featured more efficiency, practicability, low-cost and high-quality isincreasingly popular among the consumers. Through researching on quality changingrule of the small packaged rice, the storage problems of rice could be improved.In this experiment, fresh Longjing Chahayang3rice are taken as experimentalmaterial. Through adopting different storage approach, the representatives of thephysical and chemical indicators, such as water, fatty acids, reduction sugar andamylase are selected every40d with rice stored in a sealed bag of scheduled N2andCO2mixing concentration and temperature. Through combining with the changes ofcooking quality, texture characteristics and taste value, the stable conditions affectedrice quality could be elected. Since all modified atmosphere packaging of rice need tobe lift packaging before it is eaten, therefore, this study，according to the study of theirtypical quality and food quality after unblocking of modified atmosphere packagingunder storage of selected stable conditions, is aimed to provide a theoretical basisand data support for the development of high-end rice and new food packagingtechnologies. The main research programs and results are as follows:The rice samples were stored at5℃,10℃,15℃,20℃with100%CO2and N2and other different proportions atmosphere CO2: N2(1:4,1:1,4:1) by air conditioners,observing every40d to measure its various indicators. After continuous measurementof200d, the physical and chemical indicators’ changes represented by water, fatty acids and are researched and analyzed. The comprehensive analysis shows thephysicochemical quality of rice reaches best stability under the proportion ofatmosphere storage controlled at CO2and N21:1. Temperature5℃could best delaythe deterioration of the quality rice, but the difference between10℃and15℃is notsignificant (p>0.05), and both of them could delay the deterioration of the quality ofrice. The15℃has the highest cost performance. The water content did not changesignificantly (p>0.05) at15℃atmosphere ratio of1:1, fatty acid grew by104%(p<0.05), catalase activity decreased by4.9%(p<0.05), reducing sugar grew by68%(p<0.05) and amylose increase by1.7%(p<0.05).The significant indicators affected on the value of eating are the rice waterabsorption, swelling, dry matter content of rice, rice ph, hardness, and elasticityrespectively. It shows that the seven indicators closely related to the rice taste valueand can be used to evaluate the consumption of rice quality.The rice water absorption and swelling are gradually increased with prolongedstorage time of rice under different storage conditions during the200d, pH of the ricesoup and dry matter decreases gradually, and the increase magnitude will vary withthe increasing of storage temperature. The results measured by texture analyzershows that rice hardness, elasticity is growing with prolonged storage time and bothchew and taste value will decrease, low temperature under the gas ratio of1:1hasrelatively more stable effect on the physical and chemical indicators.According to the first two chapters’ experiments, rice under temperature15℃, gasratio of1:1, vacuum conditions and natural storage conditions were selected andre-opened after the removal of modified atmosphere packaging. Physical andchemical properties of fatty acids, edible quality and sensory evaluation weremeasured for every7d. Three35d storage rice taste decreased, compared with thevacuum packaging and natural packaging, eating scores decreased rapidly of modifiedatmosphere packaging after re-opened, while eating quality of21d rice has nodifference (p>0.05). The results suggest that, although modified atmospherepackaging can better maintain rice freshness, extend shelf life of rice, but itrecommended to enjoy it within14d after lifting the package in order to obtain the best rice edible quality and taste.