Study on Quality Change of Rice Bran Treated by Microwave Collaborating with Water Regulating During Storage
In this study,the change of enzyme activity in rice bran,the quality of rice bran and the changes of physiological active substances were investigated by microwave collaborating with water regulating during the storage.The results indicated that adjustment of initial moisture content had obvious synergistic effects on microwave stabiliza-tion of rice bran,when the initial moisture mass fraction was of 24％,the peroxidase activity was of 0,lipase was a-bout 7％,and polyphenol oxidase was about 3％.With microwave power of 1 000 W,microwave time of 180 s,layer thickness of 1.5 cm and initial moisture mass fraction of 24％,the acid value and peroxide value of rice bran in 12-week storage were 21.45 mg KOH/g and 4.22 mmol/kg,respectively,the acid value was reduced by about 35％,and the peroxide value was reduced by about 26％compared with the raw material(initial moisture mass frac-tion of 11％.The influencing factors were as follows:initial moisture content of rice bran＞microwave power＞mi-crowave time＞layer thickness;the total contents of tocopherol and tocopherol decreased linearly,and the contents tended to be 0 at 12 weeks,the phenomenon which the total contents of tocopherol and tocopherol increased and de-creased only occurred at week 8 at higher initial moisture content.Microwave treatment had a significant effect on the contents of γ-tocopherol and γ-tocopherol,decreased by 50％and 33％on average.The α-tocopherol content(200 mg/kg)was lower in rice bran treated with higher initial water content.During the storage,the contents of pal-mitic acid in rice bran oil increased,while the contents of oleic acid and linoleic acid decreased.The γ-oryzanol content increased first and then decreased,reaching a maximum of about 1.35％at 8 weeks.Water regulation had no significant effect on the fatty acid composition and the oryzanol content of rice bran during storage.In order to get bet-ter quality rice bran raw materials,storage time shall not exceed 2 weeks.
NETL
NSTL
万方数据
