MOLECULAR BIOLOGY FOR IMPROVED FERMENTATION EFFICIENCY UNDERSTAND HOW YEAST CONTRIBUTE TO THE FLAVOR PROFILE OF DISTILLED SPIRITS W R I T T E N B Y J O Y G H O S H , P H . D . A N D P AT R I C K H E I S T, P H . D .
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ver the last several decades, the study of living organisms on a molecular scale has helped improve our understanding of how things work at the cellular and sub-cellular levels. This has led to some very important discoveries resulting in organisms with improved function, such as higher yielding grain crops or microbes capable of producing unique and valuable enzymes. Although distilled spirits production is often carried out using ageold techniques and protocols, there is a lot that can be learned and applied from recent discoveries in molecular biology. Here, we look at how recent advances in molecular biology are being used to improve beverage alcohol production and the potential for new product development. We will focus primarily on the yeast, Saccharomyces cerevisiae, whose performance in fermentation directly impacts flavor of the distilled spirit as well as alcohol production and yields. Although there is a clear difference between how beer, wine, and distilled spirits are made, there is one common factor—all of them involve yeast, a unicellular eukaryotic organism. The global yeast market is expected to reach around 5 billion U.S. dollars by the end of 2016, with a significant market share of that being brewer and distiller’s yeast. With the exception of any contaminating bacteria or wild yeast, it is the only living ingredient in the entire fermentation process and greatly influences the quality of fermented beverages.
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Two key factors in beverage alcohol production include yeast performance during fermentation, which directly relates to alcohol production and yields, and flavor profile of the resulting distilled spirit. Both of these factors are yeast strain specific and changes in fermentation conditions and/ or the extracellular environment of the yeast cells can induce stress and alter cell performance as well as affect the desired flavor profile of the alcoholic beverage. Recent studies in yeast molecular genetics have revealed that there are several cellular metabolic pathways that are associated with yeast performance and flavor/ aroma production. Manipulation of such pathways could result in the development of yeast strains capable of better performance under stressful fermentation conditions, and at the same time regulate or influence flavor profiles.
TYPES OF YEAST STRESS FACTORS DURING FERMENTATION Survival and productivity of yeast during fermentation is dependent on their ability to respond and adapt to a changing environment. This is especially true in the later stages of fermentation when alcohol concentrations are high and sugars have been depleted. In addition, there are other stressors which WWW.ARTISANSPIRITMAG.COM