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In this study, B. subtilis and S. cerevisiae are used for fermentation strains and the solid-state fermentation method were adopted for microbial fermentation of rice protein. The optimum conditions for a single fermentation were investigated by accordance with single factor test and orthogonal experiment. Determined by orthogonal experiments in solid fermentation conditions on the basis of the proportion of strains of Bacillus subtilis and yeast complex fermentation, inoculation, fermentation temperature, fermentation time, and ultimately determine the best conditions for complex fermentation. In addition, this study also carried out the carp breeding test using composite strain fermented rice protein replace of fish meal, and verified the practical effect of the fermentation once again. The results were as follows:Experiment1The optimization of single bacteria fermentation conditions using rice protein as materialS. cerevisiae and B. subtilis were seperately used in the fermentation of rice protein. Based on the single factor test and orthogonal experiment, optimum fermentation conditions of two strains were collected. S. cerevisiae fermentation optimum conditions were as folllows fermentation time96h, inoculum9%,55%moisture content, fermentation temperature28℃, fermentation initial pH6.0, and installed capacity30g/250mL flask. B. subtilis fermentation optimum conditions were fermentation time72h, inoculum9%,60%moisture content, fermentation temperature37℃, fermentation initial pH7.0, installed capacity30g/250mL flask.Experiment2The preliminary study of composite strain fermentation rice proteinBased on reasonable selection single fermentation of two strains(B. subtilis and S. cerevisiae), the single-factor test about the proportion of strains, inoculation, fermentation temperature, fermentation time of composite strain, and orthogonal experiment was designed to explore the best composite strain fermentation conditions. Reusults:B. subtiliss:S. cerevisiae=2:1, inoculum9%,60%moisture content, fermentation temperature37℃, fermentation time72h,installed capacity30g/250mL flask, The final fermentation product of acid-soluble protein content of26.33%. Experiment3Studies on the fermentation rice protein in the Crucian carpAn7-week feeding experiment was conducted to evaluate the effect of different levels of fermented rice protein on growth performance indicators, blood biochemical indicators,muscle ingredients indicators and small peptide transporter expression in crucian carp. The experimentation was divided into5treatment groups, there were control group,6%unfermented group,12%unfermented group,6%fermentation group,12%fermented5treatments,3parallel each treatment, each group30fishes. The results showed:the fermentation group compared with unfermented group performance has been significantly improved (P<0.05).The multifaceted indicators of6%fermentation group has no significant difference compared with the control group of fish meal(P>0.05), even better than the control group of fish meal, which proves fermented rice protein can partially substitute fish meal.
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