Multi－Utilization Of The Waste Brewing Yeast

Waste brewing yeast was the off-product in the beer brewing. The cost for the waste water treatment would be increased and the environment would be polluted if the waste brewing yeast was not reused. At the same time, there were very rich amount of useful compound in the waste brewing yeast, which was very important for extraction. There was great social and economic benefit with comprehensive utilization of waste brewing yeast. It was research on the processing of the RNA, nucleotide acids, and mannan from waste brewing yeast in the paper. The main results were as follows:First of all, the extraction of RNA was studied. The hindrance of the cell wall was reduced through the infiltration pressure with the high temperature-salting out method. The perfect techniques were established by the single factor experiment and orthogonal experiment. The operational process parameters were: yeast density 8 %, the salinity 10 %, natural pH, and incubating at 95℃for 4 hours. The yield of RNA crude extraction was 6.49 % at the process condition. Comparing the method with saturated ammonium sulfate and with the protenase, a best process for removing the protein from RNA was proposed. The neutral protenase was added with 40 u per gram dry yeast, incubated at 55℃for 1 hour, and then at 95℃for 15minutes. The nucleic acid was precipitated by using the iso-electric precipitation and alcohol sedimentation. Double volumes of absolute ethyl alcohol was added to RNA extraction, pH was adjusted to 2.5 and then was incubated at 4℃overnight. The crude product was gotten after centrifugation and drying. Finally the yield of crude RNA was 5.0 %, which was much higher than the others of domestic research. The purity of RNA was 93.6 %. The crude RNA was decomposed into four kinds of 5'-mononucleotides with 5'-phosphodiesterase. The RNA concentration was 2%, pH 7.0, incubated at 70 for 2 hours with 5'-phosphodiesterase of 30 u /mL. The total yield of four kinds of the mononucleotides was 84.2 %.The mannan was extracted from the cell wall of waste brewing yeast residual by Alcalase digest. 2 % alkali was added into waste brewing yeast residual with 8 %, Alcalase was added with 50 u/mL substrate and then incubated at 60℃for 4 hours. The yield of mannan extraction was 96.2 %, while it was 92.7 % with 750 grams of waste yeast.