Influence of Non-Saccharomyces on Wine Chemistry: A Focus on Aroma-Related Compounds

Abstract

Wine fermentation processes are driven by complex microbial systems, which comprise eukaryotic and prokaryotic microorganisms that participate in several biochemical interactions with the must and wine chemicals and modulate the organoleptic properties of wine. Among these, yeasts play a fundamental role, since they carry out the alcoholic fermentation (AF), converting sugars to ethanol and CO₂ together with a wide range of volatile organic compounds. The contribution of <i>Saccharomyces cerevisiae</i>, the reference organism associated with AF, has been extensively studied. However, in the last decade, selected <i>non-Saccharomyces</i> strains received considerable commercial and oenological interest due to their specific pro-technological aptitudes and the positive influence on sensory quality. This review aims to highlight the inter-specific variability within the heterogeneous class of non-<i>Saccharomyces</i> in terms of synthesis and release of volatile organic compounds during controlled AF in wine. In particular, we reported findings on the presence of model non-<i>Saccharomyces</i> organisms, including <i>Torulaspora delbrueckii, Hanseniaspora spp,</i><i>Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia</i> spp. and <i>Candida zemplinina</i>, in combination with <i>S. cerevisiae</i>. The evidence is discussed from both basic and applicative scientific perspective. In particular, the oenological significance in different kind of wines has been underlined.