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This study presents the behavior of the identified yeast strain S. cerevisiae, isolated from Busuioacă de Bohotin grapes from the Pietroasa winery, during the process of fermentation to obtain dry active yeast biomass for the winemaking process. In this respect, we promoted an optimization strategy for obtaining active dry yeast biomass. The cultivation conditions for micropilot fermentation (temperature, pH, carbon source, and nitrogen source) were selected and designed according to a Taguchi design with four factors and three levels. Reproducibility testing was conducted under specific fermentation parameters: temperature (32 °C), pH (4.5), carbon source (12%), and nitrogen source (0.7%). Following the optimization process, two combinations of cultivation parameters were selected, and one of them, based on the results, was selected for further analysis. Quantitative data were obtained, showing dry yeast biomass (DCW) at 1.39 g/100 mL and protein content at 45.57%. The active yeast was then used in the winemaking process for Tămâioasă Românească and Busuioacă de Bohotin varieties at Pietroasa winery for validation. This optimization aims to facilitate easy and rapid production of fresh wine yeast tailored to the local winemaking practices of Pietroasa winery, with real application potential in other viticultural areas, aligning with the terroir concept.

Yeast (including brewing yeast) and yeast-based preparations derived from bioprocesses or agroindustrial byproducts represent valuable feed additives and ingredients for ruminants. The optimization of brewing yeast biotechnological processing through fermentation mediated by the brewing yeast strain Saccharomyces pastorianus ssp. carlsbergensis W34/70 was investigated. The cultivation conditions (temperature, pH, carbon source, and nitrogen source) were selected and designed according to a Taguchi fractional experimental plan, with four factors on three levels, and their influence on the evolution of the bioprocess of obtaining the brewing yeast biomass was evaluated. The dependent variables were the yeast biomass amount in wet form, yeast biomass amount in dried form after lyophilization, dried yeast biomass wettability assayed through the contact angle (CA), protein content (PC), and dry matter content (DS). The effects that the experimental conditions had on the system responses were visualized in tridimensional space using the response surface methodology, and the combination of biotechnological parameters that ensured process quality and robustness was then determined using the Taguchi technique through its performance indicator, i.e., the signal-to-noise ratio. By optimizing the biotechnological parameters, this study provides a valuable contribution in the area of brewing yeast biomass processing, with the aim of producing probiotic yeast for ruminant nutrition.