Research On Yeast Culture Using Distiller’s Grains As The Substrate

The yeast culture is under the control of modern fermentation process, adopting the method liquid and liquid-solid processing to produce the product,it is a green micro ecology feed additive which has multiple effects such as health care and nutrition, etc. At present,many foreign products have entered our country, but the price is very expensive.In order to reduce the cost of producing yeast culture and realize the reclamation and free from pollution of the white distiller’s grains,we use low-cost white distiller’s grains as main substrate and inoculate Saccharomyces cerevisiae, firstly by adopting yeast density solid-state fermentation, we obtain the optimal culture conditions and production craft,then learn from the autolysis methods of the beer yeast slurry,we carry on yeast autolysis in this solid substrate and find the best conditions of yeast autolysis.Finally we find the laboratorial technological process of producing yeast culture using distiller’s grains as the substrate:weigh 10g distiller’s dried grains and then put into 250 ml conical flask, adding dedicated enzymic preparations for white distiller’s grains fermentation which occupying 4% of the quality of distiller’s dried grains, inoculum 0.7 million activated yeast per kilogram distiller’s dried grains, adjust the water content of distiller’s grains to 45%-50%,take the flasks into 30℃incubator to cultivate after sealing,training to 45h and 51h, respectively add 2ml nutrient solution to the substrate(add molasses which occupying 8% of the quality of distiller’s dried grains and urea which has 0.5gN/per kilogram distiller’s dried grains), shake up and disperse, at intervals of 12h reverse the material until the 72h fermentation process is complete. And then, adjust initial pH of the solid-state substrate to 6 by dilute sulphuric acid,add autolysis promoter:6% NaCl solution(w/w distiller’s wet grains),0.04% papain solution(w/w distiller’s wet grains) and 9% absolute ethyl alcohol(v/w distiller’s wet grains), control the ratio of total volume of autolysis promoter and the total quality of distiller’s dried grains to 1:1, stir and disperse, maintain 55℃autolysis 36h and then dry and crush into finished product. After yeast density solid-state fermentation,the number of yeast can eventually reach to 4 billion per kilogram distiller’s dried grains,after autolysis,the ammoniacal nitrogen can reach to 3.83 mg per kilogram distiller’s dried grains.