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

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.

Inside Current Winemaking Challenges: Exploiting the Potential of Conventional and Unconventional Yeasts

“…Nevertheless, excessive levels of H. uvarum affected the fermentation kinetics, producing wines with a nail-polish-like aroma due to higher levels of acetate esters and volatile phenolics [ 101 ]. Moreover, strains of H. uvarum may produce an excessive amount (up to 1 g/L) of acetic acid, imparting the typical vinegary smell [ 102 ].…”

Use of Non-Saccharomyces Yeasts in Berry Wine Production: Inspiration from Their Applications in Winemaking

“…The improvement of acidity by inoculation of L. thermotolerans is the result of the conversion of sugars to lactic acid. Some L. thermotolerans strains produced lactic acid at more than 16 g/L, which is significantly higher than that produced by S. cerevisiae and likely to be excessive in oenological applications . Besides the excessively high production of lactic acid, L. thermotolerans has an intermediate fermentability (7–8% v/v in ethanol), making it necessary to combine L. thermotolerans with S. cerevisiae to mitigate the acidification and to complete alcoholic fermentation.…”

“…107 Besides the excessively high production of lactic acid, L. thermotolerans has an intermediate fermentability (7−8% v/v in ethanol), 54 making it necessary to combine L. thermotolerans with S. cerevisiae to mitigate the acidification and to complete alcoholic fermentation. As expected, the ethanol production in cofermentations reached the same level as that in the control S. cerevisiae fermentation, 107 and the concentration of lactic acid in mixed fermentations showed a moderate increase compared to the control. 105 The acidification of L. thermotolerans involved in fermentation contributed to the quality improvement of the wines produced in warm climates, giving them roundness and balanced acidity and further improving their freshness.…”

pH Control and Aroma Improvement Using the Non-Saccharomyces Lachancea thermotolerans and Hanseniaspora spp. Yeasts to Improve Wine Freshness in Warm Areas

“…Therefore, biological acidification is a way to protect the wine and allows the reduction of SO 2 levels. The effect on molecular SO 2 at low pH has an impact on reducing the levels of spoilage microorganisms and, as a consequence, lowering the production of off-flavors and toxic molecules such as biogenic amines and others, thus producing safer and cleaner wines [25].…”

“…It can be observed how the high pH typical of varieties such as Tempranillo in warm areas is deleterious to wine quality, not only producing chemical and microbial instability but also making sulfites inefficient due to low molecular SO 2 levels. The natural biological acidification of Lt produces pH reductions from 4.0 to 3.5 or less resulting in molecular SO 2 levels increasing from <0.4 (dangerous) to >0.8 (safe) [25]. It should also be noted that lactic acid is a stable acid that cannot be altered or metabolized by microorganisms during wine aging.…”