Screening a Bozo Starter Culture for Potential Application in Beer Fermentation

Abstract

The aim of this study was to identify yeast strains and hop-tolerant lactic acid bacteria from Bozo, a traditional Kyrgyz-fermented beverage that has been described as a predecessor of today’s beer. The isolated cultures were screened for their potential use in beer fermentation. A functional beer beverage made from an ancestor of beer could prove innovative for craft brewing. The cultures were isolated using a selective medium (VLB-S7S-Agar, 10 International Bittering Units), as beer includes hop acids that are lethal to many lactic acid bacteria. The application of polymerase chain reaction (PCR) techniques (real-time PCR, PCR sequencing of a partial fragment of the 16S rDNA) revealed the lactic acid bacteria Lactobacillus plantarum, Lactobacillus casei, and Pediococcus parvulus as well as three different strains of the yeast species S. To produce a beer similar to the traditional Kyrgyz beverage Bozo, all-malt wort was fermented using pure cultures of the isolated microorganisms. One strain of S. cerevisiae showed traits of domestication in that it utilized maltotriose and did not produce phenolic off-flavors. The sensory properties of the produced beers were evaluated at the end of the fermentation. Changes were observed in parameters such as alcohol content and attenuation. The results show that the production of beer with Bozo-descendant yeast and bacteria strains can be an innovative way to create new products with similar positive physiological effects as described for Bozo in the Introduction.