Impact of Indigenous Non-Saccharomyces Yeasts Isolated from Madeira Island Vineyards on the Formation of Ethyl Carbamate in the Aging of Fortified Wines

João Micael Leça,José Carlos Marques,José Luis Vilchez,Vanda Pereira,Andreia Miranda,Manuel Malfeito-Ferreira

doi:10.3390/pr9050799

João Micael Leça, José Carlos Marques + Show 4 more

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https://doi.org/10.3390/pr9050799

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Abstract

The impact of selected non-Saccharomyces yeasts on the occurrence of ethyl carbamate (EC) was evaluated. Hanseniaspora uvarum, Starmerella bacillaris, Pichia terricola, Pichia fermentans and Pichia kluyveri isolated from Madeira Island vineyards were inoculated in Tinta Negra musts. Urea, citrulline (Cit) and arginine (Arg) were quantified when the density of musts attained the levels to obtain sweet (1052 ± 5 g/L) and dry (1022 ± 4 g/L) Madeira wines. The urea concentration varied between 1.3 and 5.3 mg/L, Cit from 10.6 to 15.1 mg/L and Arg between 687 and 959 mg/L. P. terricola and S. bacillaris generated lower levels of urea (<2.5 mg/L), Cit (<11.0 mg/L) and Arg (<845.6 mg/L). The five resulting fortified wines, individually fermented by the selected non-Saccharomyces yeast, were exposed to laboratory-accelerated aging at 70 °C for 1 month. From the studied yeasts, P. terricola and S. bacillaris revealed a lower potential to form EC (<100 µg/L); therefore, both yeasts can be a useful tool for its mitigation in wines.

Highlights

The use of selected indigenous starters from the complex biota of specific environments is a new trend in the wine sector [1]
The urea concentration found in sweet and dry wines sampled before alcoholic fortification was strongly dependent on the non-Saccharomyces yeast strain inoculated (Figure 1A)
These results suggest that the use of these two non-Saccharomyces strains as yeast starters can lead to high levels of urea and, a greater potential to develop ethyl carbamate (EC)

Summary

Introduction

The use of selected indigenous starters from the complex biota of specific environments is a new trend in the wine sector [1]. Studies on indigenous yeasts adapted to specific grape varieties and regions have grown in number in recent years, with the purpose of evaluating biodiversity and for selecting new indigenous strains associated with “terroir” in order to produce different types and styles of wine [2,3]. There is a growing interest in non-Saccharomyces yeasts given that selected strains can have a positive impact on wine quality. These yeasts can be inoculated singularly or included in a mix of yeast starters to compensate for their poor fermenting capacities. Yeast metabolism is responsible for producing several flavor compounds that can ensure wine quality as well as other compounds that can be related with off-flavors or even food contaminants, which can compromise its commercialization

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