## 1 Introduction  
Winemaking dates back to the beginning of civilization, but the scientific community keeps pursuing new technologies to improve the production and quality of wine. Although the yeasts that are usually selected for winemaking are from the genus _Saccharomyces_, most often of _Saccharomyces cerevisiae_ species, there is great potential in the use of non-_Saccharomyces_ yeasts. Non-_Saccharomyces_ yeasts play an important role in the pre-fermentative stage of winemaking (e.g., cold soak) and un-inoculated fermentations, characterized by the coexistence and succession of multiple yeast species and strains [1]. Recently, several non-_Saccharomyces_ yeasts with great eoncological potential are commercially available, and this is likely to continue in the near future [2]. As most non-_Saccharomyces_ yeasts show limited fermentation aptitudes, sequential or co-inoculation with _Saccharomyces_ yeasts is required for fermentation completion. The sequential fermentation is initiated by a high concentration of a non-_Saccharomyces_ species. For example, after a certain period of time or when the ethanol level reaches the desired level, _Saccharomyces_ yeasts is inoculated. In this manner, enough time is provided for the metabolic contribution of non-_Saccharomyces_ yeasts before being inhibited by _Saccharomyces_ yeasts and increasing alcohol levels, whilst avoiding stuck or sluggish fermentation [3]. Fermentation involving non-_Saccharomyces_ yeasts may bring many advantages to the wine production process and the final wine quality, depending on the yeast genus, species and strain. It is a potential solution to reduce ethanol content in wine when mitigating the effects of climate change and the premature ripening of grapes, as well as producing wines with less alcohol to meet specific consumer and stylistic requirements. It has been shown that _Metschnikowia pulcherrina_[2] and _Lachancea thermotolerans_[4], in combination with _S. cerevisiae_, are good candidates for decreasing wine ethanol content. _Schizosaccharomyces pombe_ is the highest malic acid consumer among yeasts [5] and thus can be used to decrease wine acidity through maloalcoholic fermentation [6]. On the other hand, _L. thermotolerans_ shows the potential to increase total wine acidity through the production of lactic acid [4]. In excess, acetic acid has a negative impact on fermentation and wine aroma. Although _S. pombe_ shows a tendency to produce high levels of acetic acid, an interesting strategy with sequential fermentation of _L. thermotolerans_ and _S. pombe_, proposed as an alternative to malolactic fermentation, resulted in decreased acetic acid content [7]. High sulphite levels added in various stages of winemaking may cause consumer rejection. Application of non-_Saccharomyces_ yeasts, in particular _Torulaspora delbrueckii_ and _M. pulcherrina_, in bioprotection by colonizing the environment in pre-fermatterative stages and thereby limiting the development of the potentially undesirable microbiota, offers an alternative to SO2 [8]. Moreover, non-_Saccharomyces_ yeasts can positively affect wine protein stability, either by producing more mannose-containing polysaccharides, which act as stabilizers or by acting proteolytically and reducing the levels of pathogenesis-related proteins [9]. One of the most important applications of non-_Saccharomyces_ yeasts is their use for obtaining wines with distinct aroma profiles. Non-_Saccharomyces_ yeasts are a great source of different exogenous enzymes that may affect the release of various grape-derived compounds during fermentation, including terpen, norisoprenoids, and thiols that have a positive impact on wine aroma. Their influence is more direct through the production of odoriferous fermentation aroma compounds, such as higher alcohols, fatty acids, and esters, in quantities and ratios which often differ among the species and from those obtained by _S. cerevisiae_[7]. Non-_Saccharomyces_ yeasts affect the wine's volatile composition in a species/strain-specific manner. For example, _P.