Study On Retarding The Aging Process Of Brown Rice By Modified Atmosphere Package

Brown rice has a higher nutritional value than the milled rice,which contains a variety of nutrients such as phytosterol,polyphenols.Brown rice have the effect of reducing the cholesterol content,antioxidation.With the promotion of the nutritional value of food and health,brown rice has gradually been accepted by the public.However,brown rice will gradually become aging in the circulation link,and the quality is obviously deteriorated.Fresh brown rice,Jing4155S×Huazhan,in polyethylene terephthalate(PET)bags was sealed as follows:vacuum-sealing,10%O2+90%N2 sealing,30%O2+70%N2 sealing,100%N2 sealing and air-sealing(control)under 37? for 6 months.Quality measurements were monitored every two months,including colour,microorganism,fatty acids value,MDA,debranching enzyme reducing sugar,amylose,phytosterol,GSH,phenolics and so on.In order to provide some theoretical basis for delaying the aging of brown rice.The main research conclusions are as follows:(1)Study and analysis of the influence of different atmosphere packaging conditions on the quality and physiology of brown rice during aging process:colour,microorganism,fatty acids value,MDA,debranching enzyme,a-amylase,PPO,POD,volatile substances,reducing sugar,amylose,starch grain structure,rice hardness,cohesiveness,recoverable.During aging process,colour deepened,moulds increased,alcohols decreased while aldehydes,alkanes,acids,esters increased;under different gas conditions,in 90%N2+10%O2 packaging,fatty acid value increased slowly,the debranched enzyme activity,the activity of alpha amylase,and the decrease of peroxidase activity were small,the increase of amylose content and reducing sugar content is less.And also,brown rice had more closely starch structure,smaller hardness and larger adhesiveness of steamed rice in 90%N2+10%O2 packaging.Among all,90%N2+10%O2 packaging can effectively slow down the deterioration of brown rice quality and postpone the aging,followed by vacuum packaging,which have significant difference compared to others.(2)Study and analysis of the influence of different atmosphere packaging conditions on the bioactive substances and antioxidant activity of brown rice during aging process:free phytosterol,phytostanol,POPs,GSH,phenolics,flavonoids,DPPH and FRAP.During aging process,the content of bioactive substances and the antioxidant activity were reduced in varying degrees.The content of free phytosterol in the brown rice and the decrease of phytostanol content in the vacuum package are less.The decrease of glutathione content,polyphenols and flavonoids in brown rice in 90%N2+10%O2 packaging were slow.As for the antioxidant activity,it was found that the value of DPPH in the 90%N2+10%O2 package decreased slowly to 26%and FRAP value reduced by 88%.Among all,vacuum and 90%N2+10%O2 packagings can effectively preserve the phytosterol content of brown rice,inhibite sterol oxidation,delay the decrease of phenolic content,DPPH value and FRAP value compared to others.