Non-Saccharomyces as Biotools to Control the Production of Off-Flavors in Wines.

Antonio Morata,Carmen González,Iris Loira,Carlos Escott

doi:10.3390/molecules26154571

Antonio Morata, Carmen González + Show 2 more

Open Access

https://doi.org/10.3390/molecules26154571

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Abstract

Off-flavors produced by undesirable microbial spoilage are a major concern in wineries, as they affect wine quality. This situation is worse in warm areas affected by global warming because of the resulting higher pHs in wines. Natural biotechnologies can aid in effectively controlling these processes, while reducing the use of chemical preservatives such as SO2. Bioacidification reduces the development of spoilage yeasts and bacteria, but also increases the amount of molecular SO2, which allows for lower total levels. The use of non-Saccharomyces yeasts, such as Lachancea thermotolerans, results in effective acidification through the production of lactic acid from sugars. Furthermore, high lactic acid contents (>4 g/L) inhibit lactic acid bacteria and have some effect on Brettanomyces. Additionally, the use of yeasts with hydroxycinnamate decarboxylase (HCDC) activity can be useful to promote the fermentative formation of stable vinylphenolic pyranoanthocyanins, reducing the amount of ethylphenol precursors. This biotechnology increases the amount of stable pigments and simultaneously prevents the formation of high contents of ethylphenols, even when the wine is contaminated by Brettanomyces.

Highlights

Wine quality is strongly and negatively affected by some microbial metabolites with low sensory thresholds and negative olfactory impact, including reduced sulfur compounds [1,2], volatile acidity [3], ethylphenols [4,5], and acetaldehyde [6]
It should be noted that lactic acid is a strong inhibitor of malolactic fermentation (MLF) at high doses, which occurs in many enzymatic processes and is known as product inhibition
The use of non-Saccharomyces in ternary cultures in sequential or mixed fermentations has several advantages in terms of aroma improvement, control of spoilage microorganisms, and depletion of off-flavors; it is very important to ensure the biocompatibility of the strains used

Summary

Introduction

Wine quality is strongly and negatively affected by some microbial metabolites with low sensory thresholds and negative olfactory impact, including reduced sulfur compounds [1,2], volatile acidity [3], ethylphenols [4,5], and acetaldehyde [6]. The sensory impact is quite variable because sensory thresholds can range from very low values (H2S, 1.6 μg/L) to very high concentrations (volatile acidity 0.3–0.6 g/L), so the range is about 1 million times (Table 1). This makes the analytical approach very specific and makes the use of sensitive and reproducible techniques based mainly on gas chromatography–mass spectrometry (GC-MS or GC-MS/MS) instruments essential for their determination [7]. This review is focused on the elimination of off-flavors by using non-Saccharomyces yeasts that are able to control pH by bioacidification or to decrease the 3coofn1c2entration of precursors of molecules responsible for sensory defects

Bioprotection

Apiculate Yeasts and Volatile Acidity

Biocompatibility

Depletion of Off-Flavor Precursors

Findings

Conclusions