The impact of nutrients on aroma production by S. cerevisiae, non-Saccharomyces yeasts and lactic acid bacteria in mixed fermentations


Project Number
IWBT-Y 16-01

Project title
The impact of nutrients on aroma production by S. cerevisiae, non-Saccharomyces yeasts and lactic acid bacteria in mixed fermentations

Project leader
Rossouw, D

Institution
University of Stellenbosch. Faculty of AgriSciences. Institute for Wine Biotechnology

Team members
Rossouw, D
Bauer, F F
Du Toit, M
Divol, B
Musarurwa, H
Jolly, N P

Project description
The screening of wine microbiomes has yielded new species and strains of yeast (Saccharomyces and non-Saccharomyces) and lactic acid bacteria (LAB) with significant potential to improve the winemaking process and wine character and quality. These species and strains were selected for features such as reduced production of off-flavours, more balanced fermentative activity, reduced ethanol yields and more diverse and novel aromatic features.

This research aims to improve the understanding of the impact of single species and of mixed fermentations on the aromatic properties of wine, and in particular to establish links between specific nutrient composition of a must, selected environmental factors controlled during winemaking and the resulting aromatic features of a wine. Internationally a significant research efforts are directed towards understanding the impact of grape must composition and nutrients on the growth and metabolic activities of microorganisms during wine fermentation.

Much remains unknown regarding the utilisation of nutrients by yeasts and LAB, the impact of specific nutrients and mixtures of nutrients on aroma compound production and the final quality of the wine. If optimal fermentation supplements are to be formulated, a deeper knowledge is required regarding the impact of specific nutrients (i.e. amino acids) on the aroma compounds produced by S. cerevisiae, non-Saccharomyces yeasts and LAB. In light of the growing trend towards inoculation of mixed species starter cultures the impact of nutrients on microbial interactions and aroma outcomes in co-inoculated (S. cerevisiae, non-Saccharomyces and LAB) fermentations also need to be evaluated comprehensively.

The present application proposes to investigate aromatic outcomes in complex environments and in particular to multispecies and mixed fermentations supplemented with different nutrients. Such an approach will yield data that are of direct relevance to practical winemaking, and will lead to the development of better microbiological tools, an aroma prediction model and practical strategies to achieve desired outcomes.

Poster(s)
Lombard, J, Musarurwa, H T, du Toit, S C and Bauer, F F. 2016. Characterizing Wickerhamomyces anomalus and Kazachstania aerobia: aroma biosynthesis and fermentation kinetics when co-cultured with Saccharomyces cerevisiae. Poster presented at Macrowine. 27 June – 30 June, Changins, Switzerland.

Buica, A, Vannevel, S, Fedrizzi, B, Herbst

Presentation(s)
Musarurwa, H.T, McKinnon, A, and Bauer, F.F. 2016. The impact of branched chain and aromatic amino acids on fermentation kinetics and aroma biosynthesis by wine yeast. Paper presented at Macrowine. 27 June – 30 June, Changins, Switzerland.

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