Episode 152

Evaluation of FPDM for STA1 Positive (Diastaticus) Yeast in the Brewery


December 2nd, 2019

26 mins 19 secs

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About this Episode

Saccharomyces cerevisiae var. diastaticus is a beer spoilage yeast, with contamination leading to off-flavors, over-attenuation, and over-carbonation, potentially causing gushing beer, exploding packages, or non-compliance with Alcohol by Volume reporting. Many diastaticus yeast are commercially available, high-attenuating strains, but wild strains have also been isolated in beer. Regardless of the source of contamination, re-fermentation of finished beer by diastaticus is caused by the secretion of a glucoamylase. In finished beer, glucoamylase breaks down unfermented dextrins, creating newly fermentable carbohydrates. Outside of PCR-based genetic screening, there exists no easy method for detection of diastaticus contamination by the brewery quality control lab. Matt Linske joins us live from the 2019 Master Brewers Conference to discuss his evaluation of Farber Pham Diastaticus Medium (FPDM) for the enrichment and detection of diastaticus, and provides tips for effective use of FPDM in the brewery.

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