Enological repercussions of non-Saccharomyces species

The bulk of the sugar fermentation in grape juice, in order to produce wine is carried out by yeasts of the genus Saccharomyces, mainly S. cerevisiae. However, S. cerevisiae is not the only wine yeast, as spontaneous grape juice fermentation involves a complex succession of growth and death of different yeasts [1,2], and each of them contribute to the organoleptic properties of the final product. Saccharomyces are not usually found in the epiphytic yeasts present on the surface of grapes, where Hanseniaspora, Candida, Pichia, and Hansenula are dominant [3]. However, Saccharomyces imposes itself due to its higher tolerance to the stressful conditions of fermentation, due to its resistance to the addition of sulfite and to the ethanol that it itself produces [4]. Therefore, most non-Saccharomyces species relevant to winemaking have been traditionally overlooked, except when they act as spoilage agents [5]. However, the use of selected non-conventional yeasts to improve the organoleptic properties of wine is probably the most exciting trend in modern enological microbiology [6,7,8]. This Special Issue gives a complete picture of the most promising non-Saccharomyces strains and their contributions towards more complex and balanced wines.This work has been funded by a grant from the Spanish Ministry of Economy and Competiveness (AGL2017-83254-R).Peer reviewe