Screening Of Highly Degradable Free Gossypol Sulfate Strains And Preliminary Study On Solid State Fermentation

Cottonseed meal(CSM)with high concentration of protein is a very good resources of plant protein feedstuff. But due to the presence of free gossypol toxic animal, which greatly reduced the utilization value. Therefore, a number of methods have been developed for removing free free gossypol(FG). Such as organic solvent extraction, ferrous sulfate, calcium hydroxide treatment processing and fermentation etc. At present, the use of microbial fermentation detoxification is considered to be the best method, The method can not only free gossypol cottonseed removal, but also can improved cottonseed protein, amino acids, as well as some pro-growth factor contents. Therefore, it has been widespread concerned.In the present study, a strain with high efficiency of free gossypol detoxification was screened out; The process parameters for fermentation material pretreatment and fermentation detoxification was optimized; The factors which can affecting fermentation had been investigated; In addition, through the further investigation of the changes of the material before and after the fermentation, the fermentation effect of the Monascus purpureus fermentation was studied. As follows:1. A strain with high efficiency of free gossypol detoxification was screened out. Through all the existing laboratory strains blind screened, screened strains biodegradable free gossypol, and ultimately selected Monascus as the experimental strain.2. The process parameters for fermentation material pretreatment was optimized. Based on single factor experiments, through the orthogonal experimental design, from the heating time A(10 min, 15 min, 20 min), cottonseed humidity B(50 %, 60 %, 70 % moisture) and heating temperature C(100 ℃ and 110 ℃, 120 ℃) 3 factors and 3 levels to proceed, according to L9(34) and design of experiment, which nine study different treatment group of cottonseed free gossypol(FG) with the effects of gossypol in study the change rule. Through the analysis, the factors of free gossypol in cottonseed degradation rate of primary and secondary influence humidity > temperature > time, that is, the influence of humidity maximum, followed by temperature, time of minimum comprehensive factors, the optimum condition of pretreatment for A3B3C3, 20 min, the humidity of 70 % and 120 ℃ treatment effect was the best. Under the optimum conditions for degradation experiments to about 290 mg/kg, the degradation rate was 96.2 %.3. The process parameters for fermentation detoxification was optimized. The solid state fermentation conditions were optimized by single factor and orthogonal design, first of all to humidity, inoculation, fermentation temperature, fermentation time, the thickness of the solid state fermentation do single factor optimization experiments and of the four factors do L25(56) experimental design, which nine treatments, study of different treatment combinations, effect of cottonseed in free gossypol(FG) in study the change rule. Then select the best solid-state fermentation by the end of the minimum free gossypol content and nutrients to changing circumstances. The factors to influence the degradation rate of free gossypol in cottonseed for quantity of primary and secondary :inoculums > temperature > fermentation thickness > humidity, that is the influence of inoculation amount is maximum, followed by temperature, thickness of the fermentation and humidity. Taking all factors, the best fermentation conditions is A4B2C3D5, namely 32 ℃ culture temperature, 60 % ratio of humidity, 10% of inoculation, the fermentation thickness of 2.5 cm of the treatment effect best. Under the best conditions experimental verification degradation to about 80 mg / kg, a degradation rate of 72.5 %.4.The changed between before and after fermentation detoxification. Through the fermentation of Monascus detoxification cottonseed without mildew and other undesirable changes and loose texture, rich flavor. The content of the acid in the cottonseed was decreased by 46.9 %. The content of crude protein in cottonseed was improved from 45.83 % to 49.15 %. The large molecular proteins are converted into small proteins, which greatly improve the nutritional value of cottonseed.