Skip navigation links

2017 Master Brewers Conference
20. Spoilage risk-based analysis of Lactobacillus and Pediococcus brewery isolates in beers having diverse properties

Kristen Kahle, Invisible Sentinel, Philadelphia, PA, U.S.A.

Coauthor(s): Kelly Maher, Stone Brewing Co., Escondido, CA, U.S.A.; Michaela Feeney, Invisible Sentinel, Philadelphia, PA, U.S.A.

Yeast, Fermentation, and Microbiology II
Thursday, October 12
3:30–5:15 p.m.

A major challenge in maintaining beer quality is early detection of spoilage microorganisms before they have the ability to produce unintended flavors and aromas. Spoilage organisms can be diverse and present different quality risks based on their potential to thrive in beer and in the brewery. Early detection coupled with risk-based analyses can provide invaluable information to quality-centric brewers. A novel molecular diagnostic assay, Veriflow brewPAL, was developed to provide accurate and sensitive detection of beer-spoiling Pediococcus and Lactobacillus species in under three hours. In this study, Veriflow brewPAL technology was used to assess bacterial growth in beers having diverse properties. Numerous factors may influence the ability of Lactobacillus and Pediococcus species to metabolize and affect the quality of beer, including levels of hops resistance genes in bacterial isolates and percent ABV, IBU, gravity, malt builds, and respective substrates in beer formulations. The effects of these factors on Lactobacillus and Pediococcus growth were evaluated with the ultimate goal of developing a comprehensive, validated model for beer spoilage risk assessment that could be used by breweries to preserve the quality and therefore the taste and value of the beer they produce. Lactic acid bacteria strains were isolated from different locations within a brewery setting. Each isolate was genetically characterized to determine strain identity and the hops resistance gene profile. Following characterization, select strains were grown in beers having distinct properties in order to determine the factors that are major predictors of spoilage risk. Bacterial growth in each beer was measured and quantified using the Veriflow brewPAL system to determine overall risk of spoilage, which was subsequently correlated to the properties specific to each beer. While ABV and IBU are important factors that can influence the risk of beer spoilage, the results of these studies revealed additional properties are strong modulators of bacterial growth, including the utilization of specialty malts. These findings can be used as a guide to help predict whether conditions within a particular beer are favorable for rapid bacterial growth and subsequent spoilage, thereby providing brewers with the ability to make early and informed decisions to maintain the quality of their products.

Kristen Kahle, Ph.D., is the director of research and development at Invisible Sentinel, a global molecular solutions company that provides microbial diagnostic tools for multiple industries including food safety and beverage quality. At Invisible Sentinel, Dr. Kahle leads the scientific team that developed brewPAL, a rapid molecular test for the detection of beer spoilage organisms, in partnership with several award-winning breweries. Dr. Kahle specializes in the development of quantitative assays to identify spoilage organisms and has successfully commercialized new technologies for data analysis. Dr. Kahle earned her M.S. degree in biotechnology from The Pennsylvania State University and a Ph.D. degree in molecular pharmacology and structural biology at Thomas Jefferson University. Dr. Kahle has extensive experience investigating viral and microbial pathogens, resistance mechanisms, and previously designed inhibitors to mitigate the effects of these biological agents. She has numerous publications in the field of microbiology and host/pathogen interactions.