Effects Of Cottonseed Meal Detoxification By Biological Fermentation

In the present study, biodegradation of free gossypol (FG) by C. tropicalis ZD-3 was carried out under solid state fermentation (SSF). The process parameters for fermentation detoxification was optimized and factors of affecting fermentation detoxification were also investigated.Experiment 1. To optimize the process parameters for detoxification of gossypol in cottonseed meal (CSM) by C. tropicalis ZD-3 during solid substrate fermentation (SSF). The maximum detoxification efficiency of gossypol was achieved by employing the substrate which consists of 70% of CSM, 20% of corn flour and 10% of wheat bran. The optimum fermentation conditions for gossypol detoxification are incubation period of 48 h, incubation temperature at 30℃, inoculum level 5% v/w, moisture content of solid substrate 50% and pH in nature.Experiment 2. Heat treated CSM substrate was fermented by C. tropicalis ZD-3, free gossypol (FG)were determined. The objective was to study the effect heat treatment on the reduction of gossypol levels during solid substrate fermentation of CSM. The results showed that heat treatment was instrumental in reducing gossypol levels during CSM fermentation.Experiment 3. Different treated CSM substrate was fermented by C. tropicalis ZD-3, then free gossypol (FG), crude protein (CP) content were determined in CSM substrate. The objective was to study the effect of carbohydrate sources on the reduction of gossypol levels during solid substrate fermentation of CSM. The results showed that CSM substrate supplemented with selected carbohydrate sources was beneficial for fermentation detoxification, of which, starch was most effective, detoxification efficiency upped to 91.91%.Experiment 4.CSM substrate was added with 0, 0.5%, 1% and 2% of ethanolamine (or choline chloride) respectively, mixed evenly, then heat treatment and fermentation experiments were carried out. The results showed that CSM substrate supplemented with different percentage of ethanolamine or choline chloride was not beneficial for CSM heat treatment and fermentation detoxification.Experiment 5.CSM substrate was treated with different concentration of ethanolamine, choline chloride, lecithin and heated whole soy, then fermented by C. tropicalis ZD-3. After fermentation ,to assay the FG content and neutral, alkaline and acetic proteinase activity, as well as microbial numbers in fermented CSM substrate. The objective was to study the effect of ethanolamine, choline chloride, lecithin and heated whole soy on CSM fermentation.①The results showed that when substrate was heated, ethanolamine, choline chloride, lecithin and heated whole soy had no efficiency for fermentation detoxification, decreased detoxification rate significantly except for choline chloride; neutral proteinase activity was increased markedly by choline chloride, ethanolamine and lecithin; alkaline proteinase activity was improved greatly by choline chloride and lecithin; and acidic proteinase activity was elevated significantly by all treatment factors; microbial numbers in fermented substrates was increased markedly by all treatment factors, of which, the effect of choline chloride was best.②The results demonstrated that when substrate was not heated, ethanolamine, lecithin and heated whole soy had no efficiency for fermentation detoxification, decreased detoxification rate significantly, but choline chloride had the trend of improving detoxification rate; the neutral proteinase activity was increased greatly by lecithin and whole soy; the alkaline proteinase activity was elevated markedly by all treatment factors, but acidic proteinase activity was decreased significantly by all treatment factors; microbial numbers in substrate treated with choline chloride was increased greatly, whereas treated with others, microbial numbers were decreased significantly.③The results showed that choline chloride had important implication for fermentation detoxification of CSM, because its substrate proteinase activity was higher and microbial numbers was larger than other factors. When substrate was not heated, lower concentration of choline chloride could facilitate fermentation detoxification.