The Effect Of Nitrogen-filled Storage On The Quality Of Brown Rice

According to the United Nations Food and Agriculture Organization(FAO),the amount of 15%?16%of the rice world-wide suffered the loss due to the unsuitable storage and processing conditions.China takes the first place in grain production and consumption,hencescientific and reasonable storage techniques of rice would be of great practical significance.Aging during storage resulted in numerous changes in the chemical and physical properties of rice.Therefore,the effective,green and healthypreservation techniques of rice have become increasingly urgent.At present,the utilization of controlled atmosphere storage and coating the grain with bioactive compound substances for rice storage has been attracted more attention in food and agriculture scientists.In this work,the effects of nitrogen-filled storage and nitrogen-filled combined with 0.15%rosemary extracts coating storage were studied compared to natural sealed storage.The quality changes of brown rice after opening the package(unsealed,removing nitrogen)were also investigated.The main contents and results are as follows:Firstly,the changes in chemical compostion,colors and the amount of microorganism of brown rice during storage were investigated.Compared to natural sealed storage,nitrogen-filled combined with 0.15%rosemary extracts storage and nitrogen-filled storage were more effective in slowing down the loss of moisture,the reduction of the content of crude fat and free sulfhydryl,and the increase of total number of molds and yeast colonies.Nitrogen-filled combined with 0.15%rosemary extracts storage showed the most effective effect on antioxidant and antibacterial of brown rice during storage,compared to nitrogen-filled storage and natural sealed storage.Meanwhile,nitrogen-filled storage was more effective in lowering the changes of starch content and sugar content.Moisture content in each group increased firstly and then decreased after opening the package(removing nitrogen)while the number of bacteria and fungi increased with the storage time.The variation range of the content of crude fat,MDA,free sulfhydryl,amylose,reducing sugar and fatty acid value is greater than groups with nitrogen.And the changes in the contents of fatty acid,MDA,free sulfhydryl and reducing sugar of brown rice in nitrogen-filled groups and nitrogen-filled combined with 0.15%rosemary extracts groups were more significant than those in natural sealed storage group druing storage.However,the changes in whiteness and b*values of brown rice of nitrogen-filled combined with 0.15%rosemary extracts groupswere more obvious,indicating that coating the grain with rosemary extracts was at the disadvantage in maintaining the appearance and colors of brown rice.Secondly,physiological changes of brown rice during storage were studied.Nitrogen-filled storage and nitrogen-filled combined with 0.15%rosemary extracts storage can effectively reduce the change rate of the total acid,leachate conductivity,the activities of lipase,a-amylase and catalase of brown rice.Nitrogen-filled storage could significantly lower the increase rate of conductivity and the decrease of?-amylase activity and catalase activity.After nitrogen removed in each group,the variation range of total acid,leachate conductivity,lipase activity,?-amylase activity and catalase activity is greater than groups with nitrogen,especially in nitrogen-filled group and nitrogen-filled combined with 0,15%rosemary extracts group.However,the germination rate of brown rice in nitrogen-filled combined with 0.15%rosemary extracts group decreased most significantly,followed by nitrogen-filled group,indicating that rosemary extracts are not good for germination.Thirdly,the changes in cooking quality and pasting characteristics of brown rice during storage were also studied.Nitrogen-fillied storage and nitrogen-fillied combined with 0.15%rosemary storage could decrease the following items' changing rate to varying degree:water absorption of brown rice,pH value,dry matter content and iodine blue value of rice soup,hardness and elasticity of cooked rice.The decreases in pH value and the content of dry matter of rice soup were most modest in nitrogen filling combined with 0.15%rosemary group.After opening the package,the amplitude of variation of water absorption of brown rice,pH value,dry matter content and iodine blue value of rice soup,hardness and elasticity of cooked rice is greater.Nitrogen-fillied storage and rosemary exhibited insignificant effect on expansivity rate of brown rice and cohesion and resilience of cooked rice.In nitrogen-fillied combined with 0.15%rosemary group,peak viscosity,bottom viscosity,final viscosity,pasting temperature and setback value of brown rice were smaller than those of nitrogen-fillied group and natural sealed group,indicating that rosemary can maintain better gelatinization property while nitrogen-fillied storage showed insignificant effect on gelatinization property of brown riceIn summary,compared to natural sealed storage,nitrogen-fillied storage would be more effective to maintain the quality of brown rice during storage.And coating the rice grain with rosemary extracts could slow down significantly the oxidation of fat and inhibit the growth of bacterial of brown rice.After removing the nitrogen,quality deteriorating of brown rice was more obvious.