Study On Nattokinase And Bioactive Peptides Of Peanut Meal By Solid State Fermentation

Peanut meals as the substrate were fermentation by using Bacillus subtilis,in order to explore the optimum conditions of nattokinase and antioxidant activity,ACE inhibitory peptides,respectively.To provide theoretical and practical basis for utilization of peanut meal.This paper is divided into the following four parts:1.The peanut meal was fermented by Bacillus natto to prepare nattokinase.The technological conditions were optimized by single factor and orthogonal experiments with a primary indicator of nattokinase.The results showed that the optimal conditions were as follows: fermentation temperature 37 ?,inoculum size10%,the ratio of solid/liquid 1:0.4 g/m L,fermentation time 24 h.Under the optimized conditions,the activity of nattokinase reached 3162 U/m L,18% higher than that obtained in one-factor-at-a-time experiments(only 2680U/m L).And soluble nitrogen reached 5.6 mg/m L.2.By single factor experiments,?-cyclodextrin,maltodextrin,starch sodiilm octenylsuccinate were selected,which have better protective effect on nattokinase.Then by orthogonal experiments,the vacuum freeze-drying protective agent formulas of nattokinase was screened and optimized.The optimum formulas of freeze-drying protective agent were obtained as follows: 5% ?-cyclodextrin,10% maltodextrin,2% starch sodiilm octenylsuccinate.Under these optimized conditions,after vacuum freeze-drying,the remnant enzyme activity of nattokinase could be up to74.2%,which was obviously higher than using single protective agent.Treated by artificial gastric juice for 4h and artificial intestinal for 4h,the remnant enzyme activity of nattokinase could be up to 49.3%.3.This research used the Bacillus subtilis as an original strain and the index es including hydroxyl free radicals scavenging rates and reducing power.Single fa ctor and response surface methodology were used to optimize the conditions for t he preparation of antioxidant peptides from peanut meal.The results showed that th e optimal conditions were as follows: fermentation temperature 37 ?,inoculum si ze6.8%,the ratio of solid/liquid 1:0.4,fermentation time 38 h.Under the optimized conditions,results indicated that hydroxyl free radicals scavenging rates,reducing power,DPPH free raicals scavenging rates,Nattokinase activity and polypeptide were 84%,0.21,74%,1360 U/g and0.335,respectively.4.This research used the Bacillus subtilis as an original strain.The technological conditions were optimized by single factor and response surface methodology with a primary indicator of angiotensin converting enzyme(ACE)inhibitory peptides.The results showed that the optimal conditions were as follows: fermentation temperature 37 ?,inoculum size 4.6%,fermentation time 33 h.Under the optimized conditions,results indicated that ACE inhibitory activity,nattokinase activity,hydroxyl free radicals scavenging rates and reducing power were 1960 U/g,61% and 0.136,respectively.