Fermentation Of Corncob By Microorganism And Enzyme To Produce Polysaccharides And Its In Vitro Activity

In this study,corn cobs were used as raw materials,along with auxiliary materials such as bran and soybean meal,corncob polysaccharides were prepared by co-fermentation of corn cobs with microorganisms and enzymes,and then its antioxidant activity and probiotic effects were studied.This paper mainly includes the following two parts:1 Fermentation of corn cob with bacteria and enzymes to prepare crude polysaccharide1.1 Screening of Fermentation StrainsBased on the yield of corn cob polysaccharides,the basic culture medium for corn cobs was cultured in the manner of single strains of bacteria,double strains of bacteria,and bacterial ratios against Bacillus subtilis,Bacillus licheniformis,Lactobacillus plantarum,and Saccharomyces cerevisiae.The best bacteria and their combinations,bacteria ratio screening.The results showed that Bacillus subtilis and Saccharomyces cerevisiae fermented corn cobs at the ratio of 1:9 to produce polysaccharide with the highest content of 167.27 mg/g,which was 121.7% higher than the content of polysaccharide in raw material 75.45 mg/g.1.2 Screening of enzymesBased on the combination of fermentation strains and the determination of ratios,the production of corn cob polysaccharides was used as an index,and single enzyme fermentation and dual enzymes were used for the four enzymes of cellulase,xylanase,pectinase,and mannanase.Fermentation,enzyme ratios,and enzyme amounts are selected to screen for optimal enzyme additions.As a result,it was found that the optimum enzyme for fermenting corn cobs was cellulase and the amount added was 1000 U/g.1.3 Screening of synergistOn the basis of the previous experiments,corncob polysaccharide production was used as an index,and the Plackett-Burman test was designed to use sodium humate,urea,ammonium sulfate,triammonium citrate,dipotassium hydrogen phosphate,potassium dihydrogen phosphate,manganese sulfate,zinc sulfate,copper sulfate,magnesium sulfate,and Tween 80.The 11 substances were selected as fermentation synergists.As a result,it was found that none of the synergists selected in this experiment was added to the fermentation substrate.1.4 Screening of fermentation conditionsOn the basis of previous experiments,with the corncob polysaccharide production as an index,the single-factor test was used to screen the fermentation conditions for the simultaneous production of corncob polysaccharides by bacteria and enzymes.The results showed that the best fermentation time was 48 h and the fermentation temperature was 35°C.The total inoculum size was 8%,and the ratio of solid to liquid was 1:0.8.The corncob polysaccharide content obtained under this fermentation condition was 395.97 mg/g,which was 424.8% higher than the polysaccharide content of raw material 75.45 mg/g.1.5 Analysis of nutritional quality of fermented corncobBy measuring crude protein,crude fat,neutral detergent fiber,acidic detergent fiber,calcium,phosphorus,crude ash,polysaccharides,reducing sugars,soluble total sugar,and solubles,the changes of nutrients in unfermented raw materials and corncob by co-fermentation of microorganisms and enzymes were studied.As a result,it was found that the corn cob after fermentation had calcium(0.46%),phosphorus(0.19%),crude fat(13.15%),polysaccharide(395.68 mg/g),reducing sugar(15.87 mg/g),the content of total soluble sugar(285.32 mg/g)and soluble matter(18.38%)was significantly increased(P<0.05)compared to unfermented raw materials;the content of neutral detergent fiber(55.04%)and acidic detergent fiber(23.23%)was significantly decreased(P<0.05).1.6 Screening conditions for extraction of corncob polysaccharidesThe single factor method was used to study the effect of different conditions on the yield of corncob polysaccharide.The results showed that the optimal extraction time was 40 min,the extraction temperature was 80°C,and the ratio of solid to liquid was 1:20.2 Study on antioxidant and probiotics of corncob polysaccharidesThe determination of reducing power and scavenging ability of DPPH free radical and hydroxyl radical of corncob polysaccharides,and the proliferation of Lactobacillus plantarum,Bifidobacterium and Lactobacillus acidophilus were also studied in this experiment.The results showed that the DPPH,hydroxyl free radical scavenging rate and reducing power of the unfermented and fermented corncob crude polysaccharides increased with increasing concentrations,and the antioxidant capacity of the fermented corncob crude polysaccharides was significantly higher than that of the unfermented corncobs(P<0.05).The unfermented and fermented corn cob polysaccharide had a proliferation effect on Lactobacillus,Bifidobacterium and Lactobacillus acidophilus,and the proliferation of Bifidobacteria was significantly higher than that of the other two probiotics(P<0.05).When the crude polysaccharide concentration was 2 mg/mL,the proliferation was strongest,and the fermented corncob crude polysaccharide was significantly higher than that of unfermented corncob polysaccharide(P<0.05).