Research On Antioxidant Activity Of Rice Bran By Solid-state Fermentation With Probiotics

In this research,rice bran were treated by solid state fermentation with co-inoculating Saccharomyces cerevisiea,Bacillus subtilisrice and Lactobacillus plantarum.Then the effect of solid state fermentation on the antioxidant capacity of rice bran was studied.The active substances of fermented rice bran extract were analyzed and explored the antioxidant activity of FRBE based on the zebrafish oxidative stress model.In order to provide theoretical reference for the development of high value-added rice bran.The paper mainly includes the following three parts:(1)Effect of solid state fermentation on the antioxidant capacity of rice branUsing scavenging ability of DPPH free radical as indicators,the effects of fermentation time,water content,sodium humate addition,enzyme types and enzyme addition on the antioxidant activity of rice bran were studied.The results showed that the antioxidant activity of rice bran was highest at 72 h fermentation time,50%moisture content,0.5%sodium humate addition,500 U glucanase addition amount,and the scavenging ability of DPPH free radical reached 85.55%.(2)Analysis of active components of rice bran extract before and after fermentationThe water extraction method is used to extract the active substances of fermented rice bran product,and the scavenging ability of DPPH free radical is used as an indicator to optimize the extraction conditions.The best extraction conditions:extraction time 60 min,extraction temperature 85℃,material-water ratio 1:20(g/mL).The results showed that the content of polyphenols,flavonoids and protein in FRBE was significantly increased(P<0.05)compared with RBE,increased by 68.17%,80.29%and 28.93%respectively.The polysaccharide content of FRBE was significantly reduced,but the mannose ratio was significantly increased(P<0.05).The rice bran phenolic acid is mainly composed of ferulic acid,caffeic acid and catechins.The content of ferulic acid,caffeic acid and catechins in FRBE reached 718.75 mg/kg,6.42 mg/kg and 9.96 mg/kg,which was significantly higher than RBE.It can be seen that fermentation can increase the solubility of antioxidant components such as rice bran polyphenols and flavonoids,change its monosaccharide composition and release more free phenolic acids.(3)Antioxidant activity evaluation of rice bran extract before and after fermentation in vivoThe effects of different concentrations of FRBE and RBE on the ROS content,lipid peroxidation and cell mortality of zebrafish oxidative stress model induced by AAPH were studied,and the activities of catalase(CAT)and superoxide dismutase(SOD)were measured.The results showed that the FRBE reduced the ROS content,lipid peroxidation and cell death in zebrafish embryo treated by AAPH,and the efficiency was better than the RBE group.In addition,FRBE can increase the antioxidant enzyme activity of zebrafish embryos.This results indicated that the water extract of rice bran could alleviate AAPH-induced zebrafish oxidative stress,and fermentation increased the antioxidant activity of rice bran.In conclusion,the synergistic fermentation of bacterial enzymes can improve the antioxidant capacity of rice bran and release more free polyphenols,flavonoids and other active substances,which can effectively alleviate AAPH-induced zebrafish oxidative stress.