Identification Of Spoilages In Top-fermented Wheat Beer

With the social progress and economic development, the requests about beer quality have been demanded increasingly. Many people like top-fermented wheat beer for its individual flavor. The identification of spoilages in top-fermented wheat beer is helpful to make targeted prevention in the practical production and to minimize the loss of production, at the same time to design a rapid detection of the spoilages which often occurred in the beer. So the identification of spoilages of top-fermented wheat beer has very important use in the improvement of beer quality and to fed back the microbial situation timely and accurately in the process of beer production.This article focuses on identification of spoilages of top-fermented wheat beer by physiological and biochemical characteristics and 16S rDNA PCR. Firstly,10 strains of spoilages of top-fermented wheat beer isolated from samples were from pilot-scale brewing tests of 2 tons, including wort, fermented beer, unsterilized beer and yeast. Then these strains were identified by physiological and biochemical characteristics and 16S rDNA gene sequencing. The results showed that 10 strains were Lactobacillus brevis, Lactobacillus lindneri, Lactobacillus casei, Lactobacillus coryniformis, Lactobacillus plantarum,, Lactobacillus paracollinoid.es, Pediococcus claussenii, Pediococcus inopinatus Pediococcus damnosus, Pectinatus cerevisiiphilus.Finally, the growth of the selected spoilages of different conditions and different beer culture medium were studied.the results of six lactobacillus were basically consistent, those grew best in MRS culture medium, the optimal temperature was 35 ℃ and the optimum pH was 5. The results of growth status of Lactobacillus brevis and Lactobacillus lindneri in MRS culture medium were coordinate with NBB culture medium; The growth status of Pectinatus cerevisiiphilus in MRS culture medium were fundamentally identical with NBB culture medium, the optimal temperature was 35 "C, the optimum pH was 6; the results of three Pediococcus grew best in NBB culture medium, the optimal temperature was 25℃ and grew preferably in pH 5 and 6.