Effect of the respiro-fermentative balance during yeast propagation on fermentation and wort attenuation

Assessment of yeast physiology during industrial‐scale brewing practices using the redox‐sensitive dye resazurin

“…It was expected that the yeast would be driven towards fermentative metabolism during propagation, despite being supplied with oxygen at regular intervals as the concentration of sugars in the wort were high (Moutsoglou & Dearden, 2020). Limiting factors in the wort such as nutrient deprivation (assimilable nitrogen or zinc ions), the production of ethanol and carbon dioxide, and a high cell density results in slower yeast growth and entry into the stationary phase (Hulse, 2003).…”

“…The medium used for brewery propagations is usually wort as it is cost-effective and provides the necessary nutrients for yeast to grow. Despite the tanks being aerated during propagation, the metabolic flux in yeast is driven towards fermentation pathways due to the high sugar content in wort, while the oxygen only supports lipid synthesis (Moutsoglou & Dearden, 2020). After reaching the desired yeast count, the yeast is pitched into a vessel for primary beer fermentation or bottles for refermentation.…”

Respiro-fermentative metabolism in yeast cultivated in solid-state culture: The Crabtree effect and ethanol production

“…Additionally, the metabolism of certain yeast is regulated by the Crabtree effect (Crabtree, 1929). Crabtreepositive yeast may produce ethanol under aerobic conditions depending on substrate or nutrient availability, leading to a reduction in biomass production (Pronk et al, 1996;Hagman et al, 2013;Moutsoglou et al, 2020). Under anaerobic conditions, acetaldehyde is the last electron accepter and is converted into ethanol under fermentative metabolism.…”

“…Respiratory metabolism is possible when oxygen is present to act as the final electron acceptor. Both pathways can coexist simultaneously resulting in a mixed (respiro-fermentative) pattern of metabolism (Gancedo and Serrano, 1989;Hagman et al, 2013;Moutsoglou et al, 2020). The activities of the different pathways can be evaluated by measuring the rates of metabolic formation or substrate uptake.…”

Cinética del proceso de fermentación de mostos en la producción de cerveza

“…La evaluación cinética de los procesos fermentativos se ha relacionado a través de modelos matemáticos con la actividad de microorganismos, los biorreactores y las consideraciones de balance para la acumulación de producto, que están en función de la biomasa y sustrato (Moutsoglou et al, 2020;Fox et al, 2019;Rodman y Gerogiorgis, 2016;Krogerus et al, 2015). El efecto térmico como parámetro importante en el desarrollo cervecero, ha sido evaluado considerablemente y se ha demostrado el efecto en su dinámica e influen cia de control en la optimización del proceso.…”