Study On Reducing The Free Gossypol And Enhancing The Nutritional Value Of Cottonseed Meal

Cottonseed meal is one of high quality plant protein resources, and the crude protein content of it is about 40%. But the free gossypol and other anti-nutritional factors in cottonseed meal have badly influenced its feed value.This subject employed microorganism fermentation method to reduce free gossypol and other toxic substances, degrade the protein in cottonseed meal to peptides and proteins with small molecular weight which could be absorbed easily by animals, accumulated some benefit products, and then improved the nutritional quality of the cottonseed meal, as well as increased the dosage added to the feedstuff.Based on the foundation of analysis methods, some strains used in this fermentation were obtained from the organisms reserved by the laboratory. A strain named B2 could significantly reduce the content of free gossypol; it was identified as Bacillus cereus. Another strain named B1 could significantly degrade the cottonseed meal protein to small peptides identified as Bacillus subtilis; two strains named Y2 and L which could bring good smell and dainty were also screened(Strain Y2 is a yeast; strain L is a lactobacillus).Sole fermentation research on strain B2 was adopted to see the effect on detoxification ratio of free gossypol. The best process parameters were confirmed: Fermentation duration was 48 h, feed to water ratio was 1 to 1, inoculums dose was 2%, temperature was 28℃and initial pH was just in nature state. On this condition, the detoxification ratio could reach to 51.9%.Also, sole fermentation research on strain B1 was adopted to see the effect on decomposition of cottonseed meal protein. The best process parameters were confirmed: Fermentation duration was 72 h, feed to water ratio was 1 to 1, inoculums dose was 4%, temperature was 30℃and initial pH was just in nature state. On such condition, the TCA-NSI could reach to 33.0%.Based on the strains screened from the organisms reserved by the laboratory and the sole fermentation research, mixed fermentation research was adopted. Finally, the optimum combination for fermentation was B1+B2+Y2+L. Inoculums dose of each organism is 1%(gross weight), fermentation duration was 48 h, feed to water ratio was 1 to 1.2, temperature was 30℃, and initial pH was just in nature state. On such condition, the detoxification ratio can reach to 53.4%. Judging from the pattern of SDS-PAGE, most of the cottonseed meal protein was decomposed to peptides with molecular weight below 10 kDa. TCA-NSI was also increased from 6.8% to 37.2%. The content of crude protein reached to 44.61%, which exceeded 3.79 percent than before.And then, the stability test was taken on the mixed fermentation process. The result showed that both the iteration and the stability were very good.