Study on Removal of Change Condition and Nutrient of Lactarius Deliciosus Fermented Cottonseed Meal
|School||Hunan Agricultural University|
|Keywords||cottonseed meal free gossypol Lactarius deliciosus solid-state fermentation detoxification response surface method|
Cottonseed meal, which contains protein as much as36%-47%, is a nutrient rich plant protein feed resource. However, the feeding value of cottonseed meal is seriously affected by the toxic substances and anti-nutritional factors, such as free gossypol and Tannin. In order to improve the nutritional value of cottonseed meal and the adding proportion in animal feed, this study, which adopted Lactarius deliciosus as fermentation strain, reduced the content of free gossypol of cottonseed meal, increased the content of crude protein and free amino acid as well as produced some protein feed of high nutritional value which has massive water-soluble exopolysaccharide, cellulase and protease. The main results were obtained as follow:1.The effects of the solid-state fermentation conditions of Lactarius deliciosus on the detoxification and the improvement of nutritive value of cottonseed meal were studied by using single-factor experiment. The results showed that the optimal fermentation conditions were as follows:the ratio of cottonseed Meal to wheat bran was6:4; the contents of (NH4)2SO4, KH2PO4and MgSO4-7H2O were0.75%,0.15%and0.15%, respectively; the fermentation temperature was28℃, the initial pH value was6.5,the ratio of mateial to water was1:1.4,the inoculation quantity was10%. Under these conditions, the detoxification rate of free gossypol was62.44%, the yield of water soluble exopolysaccharide reached15.32mg/g-dry substrate. Additionally, the content of crude protein and free amino acid increased4.33%,7.09%,the enzyme activity of CMCase, FPA and protease reached5684.7U/g-dry substrate,97.6U/g-dry substrate and4643.7U/·dry substrate.2. Based on the single-factor experiment,the influence of temperature,initial pH value, the ratio of mateial to water, inoculum size and their interactions on the degradation rate of free gossypol was evaluated by using response surface methodology. Data were analyzed with Design-Expert8.0.5b software.The results showed that the optimal fermentation conditions were:temperature28℃, initial pH value6.6, the ratio of mateial to water was1:1.38, inoculum size10.38%. Under these conditions,the rate of free gossypol degradation reached87.70%. 3. The effects of material thickness, air relative humidity and the disinfection method of fermentation room on cottonseed meal fermentation were studied by magnified and pilot production experiment. The optimal conditions of large-scale productive technology were as follows:the material thickness was9cm, the air relative humidity was90%as well as the disinfection time in fermentation room was4h with the disinfection method of UV and formaldehyde fumigation. Under these conditions, the average degradation rate of free gossypol reached89.55%, the yield of water soluble exopolysaccharide reached15.89mg/g-dry basis, the content of crude protein and total free amino acid increased4.67%and6.64%, respectively, as well as the enzyme activity of cellulase, FPA, protease reached4612.5U/g·dry substrate,94.5U/g-dry substrate and3627.6U/g-dry substrate. Accordingly, we can make a conclusion that the detoxification process which was stable and reliable could be used in the large scale production of cottonseed meal detoxification by Lactarius deliciosus fermentation.