Effect of Saccharomyces, Non-Saccharomyces Yeasts and Malolactic Fermentation Strategies on Fermentation Kinetics and Flavor of Shiraz Wines

Hélène Nieuwoudt,Maret Du Toit,Martin Kidd,Heinrich Du Plessis,Marieta Van Der Rijst,Neil Jolly

doi:10.3390/fermentation3040064

Hélène Nieuwoudt, Maret Du Toit + Show 4 more

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https://doi.org/10.3390/fermentation3040064

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Abstract

The use of non-Saccharomyces yeasts to improve complexity and diversify wine style is increasing; however, the interactions between non-Saccharomyces yeasts and lactic acid bacteria (LAB) have not received much attention. This study investigated the interactions of seven non-Saccharomyces yeast strains of the genera Candida, Hanseniaspora, Lachancea, Metschnikowia and Torulaspora in combination with S. cerevisiae and three malolactic fermentation (MLF) strategies in a Shiraz winemaking trial. Standard oenological parameters, volatile composition and sensory profiles of wines were investigated. Wines produced with non-Saccharomyces yeasts had lower alcohol and glycerol levels than wines produced with S. cerevisiae only. Malolactic fermentation also completed faster in these wines. Wines produced with non-Saccharomyces yeasts differed chemically and sensorially from wines produced with S. cerevisiae only. The Candida zemplinina and the one L. thermotolerans isolate slightly inhibited LAB growth in wines that underwent simultaneous MLF. Malolactic fermentation strategy had a greater impact on sensory profiles than yeast treatment. Both yeast selection and MLF strategy had a significant effect on berry aroma, but MLF strategy also had a significant effect on acid balance and astringency of wines. Winemakers should apply the optimal yeast combination and MLF strategy to ensure fast completion of MLF and improve wine complexity.

Highlights

Shiraz, known as Syrah (Vitis vinifera L.), is a red cultivar used internationally to produce dark-coloured and full-bodied wines that are suitable for ageing
The non-Saccharomyces yeast count decreased during the remainder of alcoholic fermentation and at the end of fermentation (18 days) the count was lower than 1 × 104 colony forming units (CFU)/mL
Thermotolerans L2 had a negative effect on lactic acid bacteria (LAB) growth and the progress of malolactic fermentation (MLF) when LAB were used in a simultaneous inoculation, but the same effect was not observed for sequential MLF

Summary

Introduction

Known as Syrah (Vitis vinifera L.), is a red cultivar used internationally to produce dark-coloured and full-bodied wines that are suitable for ageing. Shiraz is cultivated in all wine producing regions of the world, including Australia, South Africa and South American countries [1]. Wine flavor contributes to the final quality of wine and is the product of the combined effects of several volatile compounds, such as alcohols, aldehydes, esters, acids, monoterpenes and other minor components already present in the grapes, or that are formed during fermentation or maturation [1]. Wine production includes two important fermentation processes, i.e., alcoholic fermentation conducted by yeast, and malolactic fermentation (MLF) conducted by lactic acid bacteria (LAB) [3,4]. The yeasts drive alcoholic fermentation by converting grape sugar to alcohol, carbon dioxide and volatile compounds that affect the aroma and taste of wine [3,5]. At the onset of alcoholic fermentation, a large number of non-Saccharomyces species may be present, but the final stage is dominated by alcohol-tolerant Saccharomyces cerevisiae strains [3,5,6,7]

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