Study On The Microbial Fermentation Of Wheat Bran Feruloylated Oligosaccharides And Its In Vitro Antioxidant Activity

In the present study,Feruloyl oligosaccharides(FOs)was prepared by mixed fermentation with wheat bran as raw material,and the antioxidant activity of FOs initially isolated and purified was analyzed in vitro.This paper mainly includes the following three parts:1 Mixed fermentation process of wheat bran FOs1.1 screening of fermentation strainsThis test,on the basis of the wheat bran medium by dual wavelength spectrometry FOs production,in view of the Bacillus subtilis(Bacillus subtilis)and Bacillus licheniformis D3(Bacillus licheniformis D3),plant Lactobacillus P8(Lactobacillus plantarum P8),Saccharomyces cerevisiae(Saccharomyces cerevisiae),four types of fermentation strains,taking single bacterium fermentation,double bacteria fermentation,the three bacteria fermentation and four bacteria fermentation strains screening combination.The results showed that the fermentation strains composed of b.subtilis,b.licheniformis D3 and s.cerevisiae in the ratio of 1:1:1 had the highest FOs yield,which was 655.9 nmol/g,316%higher than that of the unfermented wheat bran(207.5 nmol/g).1.2 screening of synergistOn the basis of the previous test,on the basis of wheat bran medium,by dual wavelength spectrometry FOs production,B.subtilis,B.licheniformis D3 and S.cerevisiae,proportion of mixed strains fermentation,for glucose,urea,beef extract,yeast extract,peptone,sucrose and potassium dihydrogen phosphate(KH2PO4),ferrous sulfate(FeSO4),magnesium sulfate(MgSO4),calcium chloride(CaCl2)10 kinds of fermentation synergist,Synergist selection was performed through Plackett-Burman test design.The results showed that the mixture of B.subtilis,B.licheniformis D3 and S.cerevisiae was used to ferment wheat bran to prepare FOs without adding synergist.1.3 optimization of fermentation conditionsOn the basis of the previous test,on the basis of wheat bran medium,by dual wavelength spectrometry FOs production,B.subtilis,B.licheniformis D3 and S.cerevisiae:proportion of mixed strains fermentation,fermentation temperature,fermentation time,quantity and water than 4 fermentation conditions,through the single factor experiment of fermentation conditions for preliminary screening,to determine the response surface experiment center four fermentation conditions,further through the response surface experiment design and optimize the fermentation conditions.The best fermentation conditions were as below:fermentation time 58.5h,fermentation temperature 42.5?,inoculation amount 10.7%,material/liquid ratio 1:1.16.The yield of FOs obtained under this fermentation condition was 1309.46 nmol/g,which was 631%higher than that of the unfermented wheat bran(207.5 nmol/g).2 Separation and purification of FOs from wheat branBased on previous experiments,FOs prepared from wheat bran fermented by mixed bacteria was preliminarily isolated and purified by Amberlite XAD-2.According to the concentration,pH and volume of the adsorbed sample solution and the concentration,pH and volume of the desorption solution,the preliminary screening was carried out by single factor test.The results showed that the concentration of sample solution on FOs in the best wheat bran was 4 mg/mL,the pH of sample solution was 4,and the volume of sample solution was 40 mL.At this time,the adsorption rate was 83.76%.When desorption was performed,the optimal volume fraction of ethanol solution was 50%,elution volume was 15 mL,and the desorption rate was 94.80%.3 Evaluation of FOs antioxidant activity in wheat bran in vitroBased on previous experiments,the antioxidant activity of FOs in wheat bran initially isolated and purified was evaluated by determining the scavenging ability of DPPH radical,hydroxyl radical and reducing power.The results showed that the FOs in wheat bran initially purified by Amberlite XAD-2 had good reducing power and scavenging effect on DPPH radical and hydroxyl radical.When the concentration of FOs solution in wheat bran was 4 mg/mL,the antioxidant activity in vitro was basically equivalent to that of standard BHA.To sum up,B.subtilis,B.licheniformis D3 and B.cerevisiae were mixed with 1:1:1 fermentation strains.The optimal fermentation conditions were as follows:fermentation time 58.5h,fermentation temperature 42.5?,inoculation quantity 10.7%,solid-liquid ratio 1:1.16.The optimal conditions for the separation and purification of FOs by macroporous resin Amberlite Xad-2 are as follows:the concentration of sample solution is 4 mg/mL,the pH value of sample solution is 4,the volume of sample solution is 40 mL,the optimal desorption solution is 50%ethanol solution by volume fraction,and the elution volume is 15 mL.FOs obtained from wheat bran separation and purification can effectively remove DPPH radical and hydroxyl radical,and has a strong reducing power.