Kari Murad (1), Mohammad Hussain (1), Olivia Junco (1), Rachel McCormick (1), Jana McGinnis (1); (1) The College of Saint Rose, Albany, NY, U.S.A.

Yeast, Fermentation, and Microbiology

Spontaneous fermentation is dependent upon the yeasts available in the local environment. In fact, for generations brewers, bakers and vintners relied on the ferments produced by microbes present on the grains/fruits, in the facilities and floating in the air. These wild yeasts can produce desirable ferments but often travel in the company of spoilage bacteria and molds. Due to the variability in using wild yeast, most production breweries and distilleries use commercially available yeast during fermentation to ensure production quality and consistency; however, we know that nuance in bouquet and flavor often come from terroir and the unexpected in fermentation. As the second-largest apple-producing state in the United States, New York has no shortage of family orchards, some of which have turned to expanding their markets through the production of apple-based alcohols. We teamed up with orchard distilleries to collect wild yeast from the fruits during apple harvest season. Initial research isolated five potentially viable strains. The wild yeast strains were identified and then characterized for their glucose tolerance and consumption, ethanol tolerance and production, propagation potential and viability. These strains were then tested further in small-batch, beer-brewing trials.

Kari Murad received her Ph.D. degree in pathology at Albany Medical College in Albany, NY. After working in hospital-based laboratories, she was hired to teach microbiology and immunology at the College of Saint Rose in Albany, NY, in 1999. Exploits in her kitchen lab and collaborations with local farms, breweries/distilleries and food safety labs led her to design an undergraduate food microbiology research lab and subsequent food microbiology course. Relatively new to the brewing world, she has recently become a member of ASBC and is always looking forward to her next adventures with microbiology.