Effects of melatonin and tryptophol addition on fermentations carried out by Saccharomyces cerevisiae and non-Saccharomyces yeast species under different nitrogen conditions

• Published in: International journal of food microbiology Vol. 289; pp. 174 - 181
• Main Authors: Valera, María José, Morcillo-Parra, M. Ángeles, Zagórska, Izabela, Mas, Albert, Beltran, Gemma, Torija, María Jesús
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 16-01-2019; Elsevier BV
• Subjects: Alcohol; Alcohols; Alcohols - analysis; Amino acids; Amino Acids, Aromatic - pharmacology; Baking yeast; Fermentation; Fermentation - drug effects; Fungi; Growth regulators; Hanseniaspora uvarum; Indoles - pharmacology; Inoculation; Kinetics; Melatonin; Melatonin - pharmacology; Metabolism; Metabolites; Metschnikowia pulcherrima; Nitrogen; Nitrogen - metabolism; Saccharomyces; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - metabolism; Species; Starmerella bacillaris; Torulaspora delbrueckii; Viability; Wine; Wine - analysis; Wines; Yeasts; Yeasts - drug effects; Wine; Metschnikowia pulcherrima; Torulaspora delbrueckii; Hanseniaspora uvarum; Starmerella bacillaris
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2018.09.013

During wine fermentation, yeasts produce metabolites that are known growth regulators. The relationship between certain higher alcohols derived from aromatic amino acid metabolism and yeast signalling has previously been reported. In the present work, tryptophol (TrpOH) or melatonin (MEL), which are putative growth regulators, were added to alcoholic fermentations. Fermentations were performed with three different inocula, combining Saccharomyces cerevisiae and four non-Saccharomyces yeast species, under two nitrogen conditions. The combinations tested were: (i) only S. cerevisiae; (ii) the mixture of four non-Saccharomyces species; and (iii) the combination of all five species together. The results revealed that the TrpOH and MEL addition caused changes in fermentation kinetics, viability and species distribution during fermentation, but it was dependent on the nitrogen present in the media and the composition of the inocula.
Low nitrogen condition seemed to favour the presence of non-Saccharomyces species until mid-fermentation, although at the end of fermentation the imposition of Saccharomyces was higher in this condition. The presence of high concentrations of TrpOH resulted in limited growth and a delay in fermentation, noticeably significant in fermentations performed with S. cerevisiae inocula. These effects were reversed by the presence of non-Saccharomyces yeast in the medium. Low TrpOH concentration allowed faster fermentation with mixed non-Saccharomyces and Saccharomyces inocula. Moreover, in the absence of S. cerevisiae, a low concentration of TrpOH increased the presence of Torulaspora delbrueckii during fermentation with high nitrogen availability but not under low nitrogen conditions, when the population of S. bacillaris was higher than that in the control. The effects of MEL were particularly evident at the beginning and end of the process, primarily favouring the growth of non-Saccharomyces strains, especially the first hours after inoculation.
•Tryptophol and melatonin affect fermentation kinetics and population dynamics.•Nitrogen concentration modified the effect of both compounds on population dynamics.•High amounts of tryptophol delayed single S. cerevisiae fermentations.•Tryptophol changes the population dynamics in absence of S. cerevisiae.•Melatonin improves the fermentation performance of non-Saccharomyces.