title: Not your ordinary yeast: non-Saccharomyces yeasts in wine production uncovered.
abstract: Saccharomyces cerevisiae and grape juice are 'natural companions' and make a happy wine marriage. However, this relationship can be enriched by allowing 'wild' non-Saccharomyces yeast to participate in a sequential manner in the early phases of grape must fermentation. However, such a triangular relationship is complex and can only be taken to 'the next level' if there are no spoilage yeast present and if the 'wine yeast' - S. cerevisiae - is able to exert its dominance in time to successfully complete the alcoholic fermentation. Winemakers apply various 'matchmaking' strategies (e.g. cellar hygiene, pH, SO2 , temperature and nutrient management) to keep 'spoilers' (e.g. Dekkera bruxellensis) at bay, and allow 'compatible' wild yeast (e.g. Torulaspora delbrueckii, Pichia kluyveri, Lachancea thermotolerans and Candida/Metschnikowia pulcherrima) to harmonize with potent S. cerevisiae wine yeast and bring the best out in wine. Mismatching can lead to a 'two is company, three is a crowd' scenario. More than 40 of the 1500 known yeast species have been isolated from grape must. In this article, we review the specific flavour-active characteristics of those non-Saccharomyces species that might play a positive role in both spontaneous and inoculated wine ferments. We seek to present 'single-species' and 'multi-species' ferments in a new light and a new context, and we raise important questions about the direction of mixed-fermentation research to address market trends regarding so-called 'natural' wines. This review also highlights that, despite the fact that most frontier research and technological developments are often focussed primarily on S. cerevisiae, non-Saccharomyces research can benefit from the techniques and knowledge developed by research on the former.
authors.affiliation: ARC Infruitec-Nietvoorbij, Stellenbosch, South Africa.
authors.forename: Neil P
authors.initials: NP
authors.lastname: Jolly
authors.forename: Cristian
authors.initials: C
authors.lastname: Varela
authors.forename: Isak S
authors.initials: IS
authors.lastname: Pretorius
mesh_terms: D001419:Bacteria / Q000378:metabolism; D005285:Fermentation; D023281:Genomics; D012106:Research; D012440:Saccharomyces / Q000145:classification / Q000378:metabolism; D014920:Wine; D015003:Yeasts / Q000145:classification* / Q000502:physiology
keywords: aroma; fermentation; flavour; non-Saccharomyces; wine; yeasts