Combined Application of Ultra-High-Pressure Homogenization and Non-Saccharomyces Yeasts to Reduce Sulfites and Improve Wine Quality.

In recent years, the wine industry has searched for alternatives to reduce the use of sulfites, with ultra-high-pressure homogenization (UHPH) emerging as a promising technology. The objective of this study was to evaluate the combined effect of UHPH and non-Saccharomyces yeasts (Lachancea thermotolerans and Metschnikowia pulcherrima) on wine quality. To this end, fermentations were carried out using control Verdejo must, must treated with UHPH, and must treated with 50 mg/L SO2, using pure cultures and co-inoculations. Enological parameters, volatile compounds, colour, redox potential, and sensory profile were analyzed. The results showed that the co-inoculation of L. thermotolerans and M. pulcherrima reduced the final ethanol content by 0.5% (v/v) and increased lactic acid production, resulting in a decrease in pH of 0.3 units; however, L. thermotolerans in monoculture failed to implant properly in UHPH-treated must. In addition, wines from UHPH-treated musts exhibited 20% lower redox potential, suggesting that treatment with UHPH was effective in inactivating oxidative enzymes, as did those fermented with M. pulcherrima. Regarding volatile compounds, UHPH wines showed a 30% reduction in higher alcohols and carbonyl compounds, resulting in a characteristic aromatic profile that was positively evaluated in sensory analysis. In conclusion, the combination of UHPH and non-Saccharomyces yeasts represents an effective strategy for improving wine quality and reducing the use of sulfites.