固态生料发酵棉籽粕菌种筛选及发酵工艺的研究

Screening of Strains for Solid-State Fermentation of Raw Cottonseed Meal and Study on Fermentation Technology

本研究旨在考察不同菌种组合和不同工艺参数对棉籽粕固态生料发酵后游离棉酚、营养成分和有益代谢产物的影响,以优化出最佳菌种组合和发酵工艺,并获得游离棉酚显著降低、营养价值显著提升的发酵棉籽粕。棉籽粕分别通过单菌发酵、混菌同步发酵和混菌分步发酵,依据发酵后的感官评定、活菌数和pH变化以及发酵棉籽粕的游离棉酚、酸溶蛋白、粗蛋白质和L-乳酸含量为筛选指标,筛选出发酵菌种的最佳组合;通过正交试验确定棉籽粕发酵的最佳工艺条件。结果表明:1)混菌分步发酵效果优于单菌发酵和混菌同步发酵,最佳菌种组合和发酵方式为先接种酿酒酵母(Saccharomyces cerevisiae)SC17-1和植物乳杆菌(Labacillus planetarum)LP15-1进行厌氧发酵,再接种枯草芽孢杆菌(Bacillus subtils) BS15-3进行好氧发酵。2)正交试验确定的最佳发酵工艺为料水比1.00∶0.80,接种酿酒酵母SC17-1和植物乳杆菌LP15-1厌氧发酵2 d,然后接种枯草芽孢杆菌BS15-3好氧发酵2 d,发酵温度均为30℃,接种比例为酿酒酵母SC17-1∶植物乳杆菌LP15-1∶枯草芽孢杆菌BS15-3=1∶1∶10,获得的发酵棉籽粕的游离棉酚降解率为66.28%,粗蛋白质含量提高了6.38%,酸溶蛋白含量提高了88.30%, L-乳酸含量从0.01 g/L提高至1.83 g/L。由此可见,通过先接种酿酒酵母SC17-1和植物乳杆菌LP15-1进行厌氧发酵,再接种枯草芽孢杆菌BS15-3进行好氧发酵的分步发酵方式固态生料发酵棉籽粕,可有效降低棉籽粕内源毒素并提高其营养价值,这为棉籽粕的开发与利用提供了有效的技术支撑。

This study aimed to investigate the effects of different bacterial combinations and different process parameters on the free gossypol,nutrients and beneficial metabolites after solid-state fermentation of raw cottonseed meal,and optimize the best bacterial combination and fermentation technology to obtain fermented cottonseed meal with significantly low free gossypol and significantly improved nutritional value. The cottonseed meal was fermented by single bacteria,mixed-bacteria simultaneous and mixed-bacteria stepwise,respectively.According to the sensory evaluation,viable bacteria count and pH change of cottonseed meal after fermentation,and various contents of free gossypol,acid-soluble protein,crude protein and L-lactic acid of fermented cottonseed meal,the best combination of fermentation strains was screened out. Then the optimum fermentation technology of cottonseed meal fermentation was determined by an orthogonal experiment. The results showed as follows:1)the effect of mixed-bacteria stepwise fermentation was better than that of single bacteria fermentation and mixed-bacteria simultaneous fermentation. The best strain combination and fermentation method was firstly inoculated with Saccharomyces cerevisiae SC17-1 and Labacillus planetarum LP15-1 for anaerobic fermentation,and then Bacillus subtils BS15-3 was inoculated for aerobic fermentation. 2)The best fermentation technology determined by orthogonal experiment was the ratio of material to water 1.00∶0.80,inoculation of Saccharomyces cerevisiae SC17-1 and Labacillus planetarum LP15-1 for anaerobic fermentation for 2 days,and then inoculation of Bacillus subtils BS15-3 for aerobic fermentation for 2 days,the fermentation temperature was 30 ℃,and the inoculation ratio was Saccharomyces cerevisiae SC17-1 ∶ Labacillus planetarum LP15-1 ∶Bacillus subtils BS15-3 = 1∶1∶10. As a result,the free gossypol degradation rate of fermented cotton meal obtained was 66.28%,the crude protein content increased by 6.38%,the acid-soluble protein content increased by 88.30%,and the L-lactic acid content increased from 0.01 to 1.83 g/L. Based on the above results,the stepwise solid-state fermentation of raw cottonseed meal by first anaerobic fermentation of Saccharomyces cerevisiae SC17-1 and Labacillus planetarum LP15-1 and then aerobic fermentation of Bacillus subtils BS15-3can effectively reduce its endogenous toxin and increase its nutritional value,providing effective technical support for the development and utilization of cottonseed meal.[Chinese Journal of Animal Nutrition,2022,34(5):3376-3391]