Identification of wild yeast contaminants in Lager brewing process
2010
Supreecha Intree(King Mongkut's Institute of Technology Ladkrabang, Bangkok (Thailand). Faculty of Agricultural Industry. Food Sanitation Program) | Aphacha Jindaprasert(King Mongkut's Institute of Technology Ladkrabang, Bangkok (Thailand). Faculty of Agricultural Industry. Food Sanitation Program) E-mail:kvaphach@kmitl.ac.th | Sunee Nitisinprasert(Kasetsart University, Bangkok (Thailand). Faculty of Agro-Industry. Department of Biotechnology) | Adisorn Swetwiwathana(King Mongkut's Institute of Technology Ladkrabang, Bangkok (Thailand). Faculty of Agricultural Industry. Food Sanitation Program)
Contamination of wild yeasts in Lager brewing process was studied by using yeast and mold agar (YM) supplemented with 600 ppm of CuSO4. Samples were collected from 3 sources of beer processcooled wort (300 samples), pitching yeast (100 samples) and rinse water (300 samples). The data showed that rinse water contaminated with 2 percent wild yeasts, pitching yeast contaminated with 1 percent wild yeasts, while cooled wort revealed no contamination of wild yeast. Identification of contaminated wild yeasts in beer process was later studied by PCR technique. Base- sequencing in D1/D2 of 26s rRNA gene were analyzed with using primer NL1 (5'-CATATCAATAAGCGGAGGAAAAG-3') and primer NL4 (5'- GTCCGTGTTTCAAGACGG-3'). The results showed that Clavispora (Candida) lusitaniae was the major contamination of wild yeasts (33 percent ) followed by Candida pararugosa (19 percent ), Pichia spartinae (19 percent ), Saccharomyces cerevisiae (10 percent ), Candida intermedia (5 percent ), Candida orthopsilosis (5 percent ), Rhodotorula mucilaginosa (5 percent ) and Trichosporon ovoides (5 percent ), respectively.
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