Climate Change Adaptation in Winemaking: Combined Use of Non-Saccharomyces Yeasts to Improve the Quality of Pedro Ximénez Wines

This study evaluates the impact of two non-<i>Saccharomyces</i> yeasts, <i>Lachancea thermotolerans</i> and <i>Metschnikowia pulcherrima</i>, on the oenological and sensory characteristics of Pedro Ximénez (PX) white wines produced in warm regions of southern Spain. PX wines are particularly affected by climate change, often exhibiting low acidity and limited aromatic complexity. Fermentations were performed using pure and sequential cultures of these yeasts and compared to a control inoculated with <i>Saccharomyces cerevisiae</i>. Wines fermented with <i>L. thermotolerans</i> showed increased titratable acidity (up to 6.83 g/L), reduced pH (down to 3.02), and higher lactic acid concentrations, contributing to improved freshness and microbial stability. The use of <i>M. pulcherrima</i> led to a significant rise in ester production, enhancing fruity and floral aromatic notes. Sequential fermentation using both yeasts produced wines with the highest overall aromatic complexity and superior performance in sensory evaluations. These findings support the use of <i>L. thermotolerans</i> and <i>M. pulcherrima</i> as a promising biotechnological strategy to improve white wine quality under climate change conditions.