Saccharomyces and non-Saccharomyces Competition during Microvinification under Different Sugar and Nitrogen Conditions

Abstract

The inoculation of wines with autochthonous yeast allows obtaining complex wines with a peculiar microbial footprint characteristic from a wine region. Mixed inoculation of non-Saccharomyces yeasts and S. cerevisiae is of interest for the wine industry for technological and sensory reasons. However, the interactions between these yeasts are not well understood, especially those regarding the availability of nutrients. The aim of the present study was to analyze the effect of nitrogen and sugar concentration on the evolution of mixed yeast populations on controlled laboratory-scale fermentations monitored by density, plate culturing, PCR-DGGE and sugar and nitrogen consumption. Furthermore, the effect of the time of inoculation of Saccharomyces cerevisiae respect the initial co-inoculation of three non-Saccharomyces yeasts was evaluated over the evolution of fermentation. Our results have shown that S. cerevisiae inoculation during the first 48 h conferred a stabilizing effect over the fermentations with non-Saccharomyces strains tested and, generally, reduced yeast diversity at the end of the fermentation. On the other hand, nitrogen limitation increased the time of fermentation and also the proportion of non-Saccharomyces yeasts at mid and final fermentation. High sugar concentration resulted in different proportions of the inoculated yeast depending on the time of S. cerevisiae inoculation. This work emphasizes the importance of the concentration of nutrients on the evolution of mixed fermentations and points to the optimal conditions for a stable fermentation in which the inoculated yeasts survived until the end.

The utilisation of nitrogenous compounds by commercial non-Saccharomyces yeasts associated with wine

“…It is important to note what nitrogen sources are left in the grape must after non-Saccharomyces inoculation and before sequential Saccharomyces addition in order to ensure that the remaining nitrogen is sufficient for S. cerevisiae to complete fermentation as nitrogen consumption profiles of non-Saccharomyces yeasts, for example Hanseniaspora vineae and Metschnikowia pulcherrima have been shown to affect the growth of Saccharomyces yeasts . A study by Lleixà et al (2016) confirmed that nitrogen consumption by non-Saccharomyces yeasts before Saccharomyces inoculation can increase the risk of sluggish or stuck fermentations.…”

Effect of Torulaspora delbrueckii Yeast Treatment on Flavanols and Phenolic Acids of Chenin blanc Wines

“…Combination wines made during 2012 and 2013 scored lower in perceived acidity than VIN13 wines (2012 and 2013). However, succinic acid can also contribute to perceived acidity (Taillandier et al, 2014;Lleixá et al, 2016). There were significant differences in the concentration of succinic acid among wines made over the three vintages.…”

Lachancea thermotolerans, the Non-Saccharomyces Yeast that Reduces the Volatile Acidity of Wines

“…Some non-Saccharomyces, as well as some non-conventional species of Saccharomyces, present good fermentative capacities and, are able to produce wines with lower levels of ethanol and higher concentrations of glycerol [1]. They are also able to avoid stuck fermentations, as they can grow at lower temperatures [2,3] as well as being nitrogen [4] and salt tolerant [5]. Moreover, mixed inoculations of non-Saccharomyces, S. cerevisiae yeasts, and lactic acid bacteria (LAB) in sequential fermentations are of great interest to the wine industry for various technological and sensorial reasons [6].…”

“…Moreover, mixed inoculations of non-Saccharomyces, S. cerevisiae yeasts, and lactic acid bacteria (LAB) in sequential fermentations are of great interest to the wine industry for various technological and sensorial reasons [6]. In addition, a peculiar microbial footprint that is characteristic of a particular wine region may be imprinted onto a wine if inoculation with autochthonous yeast is performed [3].…”