Impact of dried, creamed and cake supply formats on the genetic variation and ethanol tolerance of three Saccharomyces cerevisiae distilling strains

Abstract

Scotch whisky fermentations typically employ high-gravity fermentation practices to maximize product formation and to minimize both energy and water inputs. This approach increases ethanol concentrations at the end of fermentation, creating stressful conditions for the yeast. In this work we examined the relative tolerance of four Saccharomyces cerevisiae distilling yeast strains, supplied in dried, creamed, cake or slurry format, to ethanol under CO 2 -induced anaerobic conditions. The cells were assessed for their capacity to recover and grow on inhibition spot plates and to maintain cell viability in ethanol-dosed suspensions. Variations in ethanol tolerance were observed between strains and between the same strain supplied in different formats. The creamed yeast format typically exhibited a higher tolerance to ethanol. One possible explanation for this observation is that cells surviving the dehydration and rehydration process might incur sub-lethal genome damage. Thus the genetic integrity of the most ethanol-tolerant strain was assessed as a function of supply format (two dried and one creamed). The mitochondrial DNA was examined using mitochondrial restriction fragment length polymorphism and the chromosomal DNA using pulsed field gel electrophoresis and polymerase chain reaction with both ITS and delta-specific primers. In one dried yeast sample, genetic integrity was compromised, highlighting the requirement for yeast intake quality assurance programmes.

Active Dry Yeast: Lessons from Patents and Science

“…Dead yeast cells induce haze in suspension in beer (Finn & Stewart, 2002). Drying and rehydration of distiller's yeast would incur sublethal genome damage (Cheung, Brosnan, Phister, & Smart, 2012).…”

Mini-Review: The Role of Saccharomyces cerevisiae in the Production of Gin and Vodka

“…Yeast is available to the distiller in several formats, the most popular being cream yeast (around 15%-20% dry matter), pressed cake (around 28%-35% dry matter), and active dried yeast (around 95% dry matter) [49,50]. The format chosen by the distiller will be influenced by the size and capabilities of the distillery.…”

“…However, large-scale industrial producers are more likely to choose creamed yeast, despite a short shelf life (of around 28 days), compared to active dried yeast (1 year). These distilleries have the production turnover to select cream yeast to be their format of choice [49,50]. Smaller (e.g., craft) distillers generally prefer dried yeast for convenience and longer shelf-life.…”

Analysis of the chemical composition and properties of the main and side products during the implementation of new technologies for producing ethanol

“…Поэтому в регулировании этого уровня большую роль играют различные кормовые добавки с повышенным содержанием протеина, включающего в себя незаменимые аминокислоты, макро-и микроэлементы, витамины [3]. В работах современных ученых доказана эффективность использования внесения ферментных препаратов на различных стадиях при переработке зернового сырья [5][6][7][8].…”