Influence of indigenous non-Saccharomyces yeast strains on the physicochemical and sensory properties of wine fermentation: a promising approach to enhancing wine quality

This study explores the potential of indigenous non-<i>Saccharomyces</i> yeasts isolated from <i>Vitis vinifera</i> L. grape skins to improve the quality of regional wines by enhancing their physicochemical and sensory characteristics. Five promising yeast strains were identified at different stages of fermentation: <i>Hanseniaspora opuntiae</i> (J1Y-T1), <i>H. guilliermondii</i> (Y5P-T5), <i>H. uvarum</i> (JF3-T1N), <i>Pichia kudriavzevii</i> (Y8P-T8), and <i>Starmerella bacillaris</i> (WMP4-T4). Among these, <i>H. uvarum</i> and <i>S. bacillaris</i> were particularly noteworthy due to their superior alcohol production, achieving levels of 8.16 ± 0.05% and 8.04 ± 0.04% (v/v), respectively, and demonstrating higher alcohol tolerance even in later fermentation stages. <i>Hanseniaspora uvarum</i> also showed exceptional resilience, with a half-life of 3.34 ± 0.03 days and a Km value of 1.0200 ± 0.0100 mol L⁻¹, achieving the highest biomass even in the later stages of fermentation. High-Performance Liquid Chromatography analysis revealed that while tartaric acid levels remained constant, malic acid content decreased, and acetic acid was produced by all strains. Solid-Phase Microextraction-Gas Chromatography Mass Spectrometry identified ethyl acetate as the dominant volatile compound, with <i>H. uvarum</i> producing the highest concentration (43.411 ± 1.602%), contributing to a fruitier aroma and flavor. The combined attributes of <i>H. uvarum</i> higher alcohol content, enhanced fruity notes, improved clarity, lower acetic acid (0.52 ± 0.03 g L⁻¹), and significant residual sugar (162.37 ± 2.48 g L⁻¹) make it a promising candidate for improving the overall quality of regional wines. Incorporating <i>H. uvarum</i> into mixed starter cultures with specific <i>Saccharomyces</i> strains could further optimize the wine fermentation process.