| Cottonseed meal was one of high quality plant protein resources,and the crude protein content of it was above 40%.However,it contain some poisonous substances,such as free gossypol and anti-nutritional factors,which extremely restrict its uses in animal feed.A number of methods have developed,microorganism fermentation method obtained a better effect.It can reduce toxic substances free gossypol and other anti-nutrient fators,degrade the protein in conttonseed meal to proteins with small molecular weight which could be absorbed easily by animals,accumulated some benefit products,as acid amino and enzyme,then improved the nutritional value of the conttonseed meal,as well as widely brought into focus.It can improve the nutritional value of the cottonseed meal by microbe with solid fermentation,which is high small peptide and used as feed scientific and effectively.As a result,we took the achievements which were followed:1 Study of screening strains on cottonseed meal by solid fermentation.The control group was the material mixed with cottonseed meal,corn flour and wheat bran in the quality ratio of 8:1:1 and grinded by 60 mash screen.Sole solid state fermentation research was adopted to see the effect on detoxification ratio of free gossypol and improvement of protein,trials were divided 12 strains treatment and 3 repeated that fermentation of cottonseed meal.Cottonseed meal could obtained better sensory and palatability after fermentation,especially Enterococcus faecalis Efl;some of strains could degrade free gossypol,Bacillus licheniformis B12 could degrade free gossypol best,free gossypol content decreased from 382.5?g/g to 219.0?g/g,detoxification rate was 42.7%;in the enzyme activity determination,Bacillus subtilis Bs1,Bs3 all showed the high activity,reaching 43.8 U/mL and 43.6U/mL,which contained much soluble protein and small pepides.Saccharomycetes increased the crude protein highly.Then mixed strain fungus fermentations test by the double and three strains were carried out on the basis of sole fermentation.Mixed culture solid fermentation of two strains gained the best effect.Finally we found best strain combination were Bacillus licheniformis B12 and Candida utilis Cu1.Free gossypol was reduced largely,and the quality of cottonseed meal was improved remarkably.The detoxification rate was up to 50.03%;soluble protein and small peptide were 9.11%and 6.98%?2 Determination of the best fermentation conditions of cottonseed meal.In order to further degrease free gossypol and improve protein content,reducing the harmful bacteria in fermentation substrate,a series trials were conducted to determine the suitable process parameters for cottonseed meal through solid state fermentation.Two trials were studied,the degradation of free gossypol and soluble protein were as the indicator for fermentation effect.Cottonseed meal substrate was treated with different concentration of urea and heating at 100? for 30min and 60min but no sterilization.After fermentation was over,it is discovered that protein enhances very obviously after the urea in 2%and at 100? for 60min.Fermentation conditions were optimized by using of single factor test with combination strains to ferment,then a orthogonal trial was taken to determine the optimal fermentative parameters,including the temperature,the vaccination quantity,the proportion of substrate and ratio of matter and water as four factor three horizontal orthogonal experiment,which ferment soluble protein and small peptide as the judgment target in orthogonal experiment.The test date was further analyzed with SPSS 16.0 software.The proportion of substrate and ratio of matter and water influenced protein content significantly(p<0.05).The appropriate conditions of solid fermentation for cottonseed meal with the collaborative enzymes were as follows:temperature was 28?,the proportion of substrate to water was 1:1,the substrate included 90%cottonseed meal,5%corn flour and 5%wheat bran,inoculation proportion of two strains was 1:3(B12:Cu1),inoculation amount was 20%v/w and the pH was in nature.Free gossypol content was under 200?g/g.Soluble protein and small peptides were enhanced from 6.4%to 20.19%and 4.93%to 15.27%and crude protein was increased 6.5%-8.7%,and then,the stability test was taken on the mixed fermentation process,the results showed well.3 Analysis nutrient components under different fermentation conditions.The experiment was conducted to investigate the active products and nutritional composition under different fermentation condition,compared with the blank.The results showed that total amino acids and essential amino acids were increased.Judging from the pattern of SDS-PAGE,most of the cottonseed meal protein was decomposed to peptides with molecular weight below 10KDa.It was discovered that fermentation could increase crude protein and reducing sugar.Meanwhile,a certain amount of protease and amylase and probiotics were produced in the fermentation,which improved the cottonseed meal nutrition value greatly.Considering cottonseed meal as low-cost resources and high feed production,this study made full use of the cottonseed meal resources and increasing the content of protein with simple technology.It was an effective way to manufacture feed for areas abundant in cotton,which provided theoretical guidance for further use of cotton seed meal and made highly economical and social benefits. |
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