Isolation, Identification, and Characterisation of Beer-Spoilage Lactic Acid Bacteria from Microbrewed Beer from Victoria, Australia

Garry Menz¹, Christian Andrighetto², Angiolella Lombardi², Viviana Corich³, Peter Aldred¹ and Frank Vriesekoop^1,*
¹ Institute of Food & Crop Science, School of Science & Engineering, University of Ballarat, Mount Helen, Australia,
² Biotechnology Group, Institute of Food Quality and Technologies, Veneto Agricoltura, Thiene, Italy
³ Microbiology Group, Faculty of Agriculture, University of Padova, Legnaro, Italy
^* Corresponding author. E-mail: f.vriesekoop@ballarat.edu.au
Parts of this paper were presented at the 2010, 31st IBD conference (Asia Pacific section) at the Gold Coast, Australia.

J. Inst. Brew. 116(1), 14–22, 2010 | VIEW ARTICLE

ABSTRACT
Lactic acid bacteria are the most frequently encountered beerspoilage bacteria, and they may render beer undrinkable due to the production of lactic acid, diacetyl, and turbidity. Microbrewed beer is typically sold unpasteurised, leaving it more susceptible to spoilage by lactic acid bacteria. In this study, the incidence of lactic acid bacteria in bottled microbrewed beer from Victoria, Australia was investigated. A total of 80 beers from 19 breweries were screened for lactic acid bacteria. Almost 30% contained culturable lactic acid bacteria, and many had lactic acid levels well above the flavour threshold. Ethanol, hops, and the pH levels of the beers were not predictors for spoilage in the beers examined, and contamination appeared to be more closely linked to the source brewery. The 45 lactic acid strains isolated from these beers were identified by RAPD-PCR, with Lactobacillus brevis being the most frequently isolated species. All isolates were capable of spoiling beer and contained putative hop resistance genes. At typical beer levels, pH and ethanol had no effect on the growth of the particular spoilage bacteria isolated in this study.

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