Optimizing Small‐Scale Production of Fresh Wine Yeast Biomass

Abstract

AbstractThe present study sought to optimize fresh wine yeast biomass production in an aerated fermenter fed with different volumes of concentrated grape must. Variables most likely to influence the process were tested at high and low levels, in a total of 13 fermentation runs. The production process was scaled up to pilot plant level, and the yeasts thus obtained were inoculated into wine fermentation tanks in a winery to evaluate their implantation during alcoholic fermentation.The best fermentation conditions were those used for batches carried out at 34C, 15°Brix and initial inoculum of 5.0 × 107 cells/mL; in these cases, cells displayed high protein and phosphorus content, a good P2O5/N ratio and appreciable accumulation of intracellular trehalose, indicating that the process was not too much stressful. Generally, biomass exhibited adequate vitality throughout storage (80%). The yeast produced retained a high degree of vitality and viability after 2 weeks of refrigeration; for this, seasonal production could, to some extent, be matched to the needs of the winery.Small‐scale laboratory production of fresh yeast biomass could help small wineries enhance the concept of terroir. This study confirmed that small amounts of fresh biomass can be sufficient as inoculum in winemaking.Practical ApplicationsThis research is related to small‐scale production of grade yeast using concentrated grape must. It has important practical applications, useful in small wine cellars.At the beginning of the vintage, the oenologist could produce their own selected yeasts and used them in wine‐making process, as biomass showed a high vitality/viability degree after 2 weeks of storage at 4C. Moreover, biomass is easier to use in small wineries, so it ensures uniform dispersal, and in the conditions studied, the biomass obtained is sufficient to inoculate tanks with an inoculum of 106 cells/mL.