Yeast: Difference between revisions

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In the brewing industry, the viability and vitality of pitching yeast are crucially important for continued successful beer-making. Yeast management before, during, and after fermentation should endeavor to minimize physiological stresses imparted on brewing yeast cultures (21,27). Stress may be imposed on brewing yeast at pre-fermentation (e.g., acid-washing, cold-shock, oxidative stress, and nutrient starvation); primary and secondary fermentation (e.g., osmostress, ethanol toxicity, pH/temperature fluctuations, and CO2/hydrostatic pressure); and post-fermentation (e.g., mechanical shear, cold-shock, and nutrient starvation). Several bioprocessrelated approaches have been advocated to maximize brewing yeast viability and vitality at different stages of yeast handling (13,31). These include nutrient-controlled yeast propagation by fed-batch cultivation, selective yeast cropping from cylindroconical fermenters, and strict control over yeast storage and acid-washing conditions.<ref>Walker GM. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-56-0109 Magnesium as a stress-protectant for industrial strains of Saccharomyces cerevisiae.] ''J Am Soc Brew Chem.'' 1998;56(3):109–113.</ref>
In the brewing industry, the viability and vitality of pitching yeast are crucially important for continued successful beer-making. Yeast management before, during, and after fermentation should endeavor to minimize physiological stresses imparted on brewing yeast cultures (21,27). Stress may be imposed on brewing yeast at pre-fermentation (e.g., acid-washing, cold-shock, oxidative stress, and nutrient starvation); primary and secondary fermentation (e.g., osmostress, ethanol toxicity, pH/temperature fluctuations, and CO2/hydrostatic pressure); and post-fermentation (e.g., mechanical shear, cold-shock, and nutrient starvation). Several bioprocessrelated approaches have been advocated to maximize brewing yeast viability and vitality at different stages of yeast handling (13,31). These include nutrient-controlled yeast propagation by fed-batch cultivation, selective yeast cropping from cylindroconical fermenters, and strict control over yeast storage and acid-washing conditions.<ref>Walker GM. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-56-0109 Magnesium as a stress-protectant for industrial strains of Saccharomyces cerevisiae.] ''J Am Soc Brew Chem.'' 1998;56(3):109–113.</ref>
yeast requires a minimal amount of inorganic-phosphate, potassium, and magnesium (250, 500, and 70 mg/L, respectively) to support yeast-growth and ethanol/flavour formation. Inorganic-phosphate was important for fatty acid esters formation/short chain fatty acid (SCFA) reduction. Potassium was important in the formation of acetate esters/higher alcohols. Magnesium was the most important inorganic element for ester formation/SCFA reduction; furthermore, ethanol production is magnesium-dependent.<ref>Ribeiro-Filho N, Linforth R, Bora N, Powell CD, Fisk ID. [https://www.sciencedirect.com/science/article/abs/pii/S0963996922011024 The role of inorganic-phosphate, potassium and magnesium in yeast-flavour formation.] ''Food Res Int.'' 2022;162:112044.</ref>