Monitoring spoilage bacteria and wild yeasts in eastern Chinese breweries

Based on 100 isolated strains of beer-spoilage bacteria and 22 wild yeast strains, this article investigates the contamination degree assessment and quality control procedures of seven breweries in eastern China. Samples were collected from five main points in each brewery: brewing water and wort; fermented beer; seed yeasts; equipment, air, and surroundings; and finished beer. All of the isolates were identified to the genus or species level by comparing their 16s rDNA, and species of wild yeast were identified as non-Saccharomyces and Saccharomyces. Determination of microorganism growth in degassed commercial lager beer indicated that approx. 80% of the bacteria had the ability to contaminate beer. This study of the occurrence of contamination in eastern Chinese breweries indicates that monitoring spoilage microorganisms is important for enhancing the sanitation quality control procedures in these plants.