Study On The Solid-state Fermentation Of Cottonseed Meal And The Degradation Of Free Gossypol

Cottonseed meal was a high-quality vegetable protein feed, which contained high contentof amino acid and its crude protein content was second only to soybean meal. But because ofcontaining free gossypol (FG), which had certain toxic effects to animals, cottonseed meal wasgreatly limited in using as animal feed. In this study, in order to reduce the content of FG, and toimprove the utilization of cottonseed meal protein, Bacillus sp. were used as the strains tofermenting the cottonseed meal in solid-state. The study had a broad application prospect, andthe main contents and results were as follows:1.Basing on the results of screening by the methods of flat transparent circle anddetermination of the protease activity of the fermentation broth, the cottonseed mealfermentation test in solid-state was done, by using the TCA-N content as the main evaluationindicator, and the bacillus strain ND-1was screened out as the fermented strains.2.With ND-1as the fermented strain, the single-factor test and orthogonal test forcottonseed meal were done respectively. The results showed that the optimal fermentationconditions such as material-water ratio, inoculant amount, incubating temperature andfermentation time were1:0.8,10%,36℃and48h, respectively, and the TCA-N content wasincreased from3.81%to22.49%, which increased by4.9times. The results of SDS-PAGEelectrophoresis analysis showed that the larger proteins of cottonseed meal were graduallydegraded to smaller polypeptide and peptide or amino acids after48h fermented.3.Adopting phloroglucinol method was used to determine the content of FG in cottonseedmeal, the results showed that the content of FG was not reduced after fermented48h under theoptimal conditions, and the results varied between mediums sterilized or not. The strains ofbacillus ND-2, JM5, JM1and all kinds of yeasts(C.lipolytica, Saccharomyces cerevisiae, JMF,L028and HL99) were all not reducing the content of FG by fermentation. It had a detoxificationrate of48.6%by autoclave treatment. Some of the FG could be removed under60℃formaintaining a longer period of time, and the detoxification rate could reach to90.0%whenmaintaining72hours. It was helpful to removing FG to adding a certain amount of Fe2+or Cu2+to cottonseed meal. 4.The result of mixed fermentation of soybean meal, cottonseed meal and rapeseed mealshowed that there would be the best results when the mixing ratio was3:2:1, and the content ofTCA-N were increased by13.0times(sterilized) and8.0times(non-sterilized), the total aminoacids were improved from0.38g/100g to6.34g/100g(sterilized) and5.05g/100g (non-sterilized),which increased by15.7times(sterilized) and12.3times(non-sterilized) respectively.