| Distiller’s grains are the waste by-products of grain brewing,which are rich in protein,fat,starch and trace elements and other nutrients.China,as a big country in the production and consumption of Baijiu,produces a large amount of distillers’grains every year.At the same time,China’s animal husbandry is facing a huge gap in feed protein.In order to improve the reuse rate of liquor making waste,and alleviate the contradiction between human beings and livestock.In this paper,the technological conditions of microbial fermentation of Maotai-flavor Baijiu distillers’grains into cell protein were explored and optimized,mainly from the decomposition and removal of cellulose in the distillers’grains,the preparation of expanded culture bacteria and the conversion of crude protein,in order to improve the conversion rate of cell protein in the distillers’grains.The main research results are as follows:(1)Optimization of the technology of degrading distiller’s grains and husksThrough L16(4~5)orthogonal experiment,the fermentation conditions of three cellulase composite agents degrading distiller’s grains and cellulose were studied,and the optimal technological conditions for the degradation of crude fiber were obtained:the amount of composite enzyme was three times,the water content of distiller’s grains was55%,p H 4.5,and treatment at 60℃for 36 hours.Under the optimum conditions,the crude fiber of distiller’s grains was reduced by 55.02%,and acid detergent fiber,neutral detergent fiber and acid detergent lignin were significantly degraded.(2)Preparation and Optimization of Brewery Grains for Extended CultureThe medium formulation and fermentation conditions of Candida utilis,Rhizopus oryzae,Bacillus subtilis and Lactobacillus plantarum were optimized by L9(3~4)orthogonal experiment.The optimized culture medium formula of the expanded culture agent was as follows:the main components were:distiller’s grains 40%+bran40%+soybean meal 20%,maltose 2%,ammonium sulfate 1%,potassium dihydrogen phosphate 0.5%and ferric sulfate 0.2%.The best fermentation conditions for expanded culture of distiller’s grains were 8%of the inoculum,60%of the substrate water content and 30℃of the fermentation temperature.(3)Optimization of the technology of transforming distiller’s grains into crude proteinThe effects of inoculum amount,substrate water content and fermentation temperature of mixed bacteria on the conversion of crude protein from distiller’s grains were studied by L16(4~3)orthogonal test.The results showed that the optimum fermentation conditions were 8%inoculum,50%water content of distiller’s grains and 20℃fermentation temperature.Under the optimal fermentation conditions,the content of true protein and crude protein increased significantly after fermentation.Under the optimal combination of fermentation conditions,the content of crude protein and true protein in Maotai-flavor Baijiu lees after fermentation was 28.76%and 19.78%,64.16%and 45.87%higher than that before fermentation,respectively.(4)Optimization of fermentation technology of distiller’s grains transformed protein feedOn the basis of the optimal expanded culture bacteria,the degradation conditions of chaff,and the crude protein conversion test obtained in research contents 2,3,and 4,the nutrient content of protein feed under different fermentation processes was compared,and the technological process of protein feed production from distiller’s grains fermented by bacteria was optimized.The protein content was 26.83%,and the crude fiber content was13.17%.The optimal fermentation process of converting distiller’s grains into protein feed was obtained.To sum up,this study obtained an optimized technology for fermentation of Maotai-flavor Baijiu lees into protein feed.By optimizing the fermentation process and fermentation conditions,the protein content reached 26.83%,and the crude fiber content was 13.17%,providing a technical reference for the resource recycling of Maotai-flavor white wine lees and the large-scale development of protein. |
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