Production, reactivation and nutrient requirements of active dried yeast in winemaking: theory and practice

Abstract

Wine yeast, from production to application, traverse an incredible range of environments. Central to their ability to not only survive but to thrive throughout this journey is their capacity to transform themselves in response to the varied conditions encountered. Wine yeast resilience alone, however, is insufficient. Producers and winemakers must be assiduous in their use of wine yeast with an understanding of yeast requirements throughout the process to achieve optimal results. Active dried yeast (ADY) starter cultures for initiating grape must fermentations are convenient, reliable and available for a wide range of strains suited to different wine types. These benefits cannot be fully realised without optimisation of: their production; reactivation of the dried product prior to inoculation; and appropriate nutrient management during fermentation. This review discusses current knowledge on production of Saccharomyces ADY for greatest biological stability and activity, and factors that affect their activity following rehydration and inoculation into grape must. The efficacy of various types of commercial additives used in reactivation of ADY and, winemaking interventions and nutrients that are used to optimise fermentation are also discussed.

Identification by phenotypic and genetic approaches of an indigenous Saccharomyces cerevisiae wine strain with high desiccation tolerance

“…Further investigations based on ‘omic’ techniques, such as genomic, proteomic and metabolomics analysis of CD‐6Sc strain, might provide new clues to gain insight into the molecular mechanisms to overcome desiccation stress. The genetic modification of yeasts with improved defences towards stress has been shown to enhance strain performance, but at this time these approaches do not represent solutions that can be deployed (Schmidt and Henschke, ). A useful alternative to this approach can be the exploitation of yeast's natural biodiversity, which may lead to the identification of indigenous strains that, in addition to possessing interesting technological characteristics, can be proposed as ADY.…”

“…In winemaking, ADY is the form most often sold worldwide, mainly because of its low volume and long storage time. Just as the basis for production of good wine begins in the vineyard, the basis for yeast performance in inoculated grape must begins with the preparation of healthy starter cultures (Schmidt and Henschke, ). In the process of transformation from living biologically active yeast to dried organisms in stasis and back again, various yeast cellular components must undergo transitions in their fundamental physical state, and in order to survive, these transitions must be traversed with great efficiency.…”

Active Dry Yeast: Lessons from Patents and Science

“…According to these authors, dry wine yeast should be rehydrated prior to incorporation into the grape must. Schmidt and Henschke (2015) have reviewed quality aspects of active dried yeast for winemaking.…”

Oxidative stress resistance during dehydration of three non-Saccharomyces wine yeast strains

“…These findings suggest that growing in nutrient-poor conditions (TSM) may have affected yeast detoxification mechanisms. Moreover, the enzymatic glutathione recycle mechanism, one of the most important ROS elimination pathways in cells, mediated by both glutathione reductase and glutathione oxidase, may have been affected during cultivation in limited nutritional conditions (TSM) (Gamero-Sandemetrio, Paya-Tormo, Gómez-Pastor, Aranda, & Matallana, 2018; Schmidt & Henschke, 2015). Indeed, glutathione can be mobilized as a source of nitrogen and sulfur under limited nutritional conditions, thus satisfying yeast growth requirements (Mehdi & Penninckx, 1997).…”

“…During ADY formulation, yeast cells undergo multiple stresses which reduce their performance, e.g. cell starvation in the course of biomass propagation then heat and oxidation induced by the drying stages (Beker & Rapoport, 1987;Rapoport, 2017;Schmidt & Henschke, 2015). In fact, cells subjected to hydric variations accumulate intracellular reactive oxygen species (ROS) as result of failure of their detoxification systems and the functionality of the proteins and enzymes responsible for the ROS elimination (Dupont, Rapoport, Gervais, & Beney, 2014).…”