 IVES 9 IVES Conference Series 9 Identification of riboflavin low producer yeasts to prevent the light-struck taste in white wines

Identification of riboflavin low producer yeasts to prevent the light-struck taste in white wines

Abstract

AIM: Wine quality maintenance during the storage is a fundamental aspect for both wine producers and consumers. Nowadays, great attention has been given to the light effect, causing detrimental changes of wine; indeed, light can induce off-flavours associated to the light-struck taste (LST)(1). This fault is due to photochemical oxidation processes in which riboflavin (RF) and methionine (Met) play an important role generating methanethiol (MeSH) and dimethyl disulphide (DMDS)(2), responsible of the unpleasant cabbage and onion-like odours that make wine undrinkable. Although it is well-known the contribution of yeasts in the final amount of these compounds in wine, microbiological strategies against the LTS defect limiting their release are not yet available. This study is part of the project “Innovative and sustainable approaches for the prevention of photo-induced defects in white wines and sparkling wines (Enofotoshield)” and in particular it aims at providing wineries with alternative microbiological approaches to counteract the LST.

METHODS: Four Saccharomyces cerevisiae strains of oenological interest (EC1118, IOC18, LS2 and AWRI796) have been compared to investigate the RF release during their growth in synthetic media (SMY and SMV) and Chardonnay must, simulating oenological conditions. Then, the RF release (including the derived flavones) was estimated by UPLC (Ultra-Performance Liquid Chromatography) analysis.

RESULTS: Results of this study revealed that RF production is influenced by the growth medium composition. Indeed, if the medium contains RF, the vitamin concentration increases over time while that of flavones remain constant; on the contrary, the opposite situation is verified in absence of RF. Moreover, investigations on other factors that could influence the RF release are still in progress (such as cell inoculum density, temperature, oxygen-limiting conditions, availability of nutrients). Taking in consideration that a lower concentration than 80-100 μg/L could limit the LST development, the best identified condition in terms of RF release was the growth on the Chardonnay must (12,8 μg/L) compared to the two synthetic media SMY and SMV (102,4 μg/L and 316,5 μg/L, respectively).

CONCLUSIONS

This study paves the way for the development of new approaches that limit the impact on the wine aromatic profile. Indeed, the choice of the growth cultural medium is a relevant factor in terms of RF and Met production. The next steps of the study will be the analysis of the Met release and of the intracellular content of both RF and Met.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Alessandra Di Canito

University of Milan,Ileana Vigentini – University of Milan Daniela Fracassetti – University of Milan Antonio Tirelli – University of Milan Roberto Foschino – University of Milan

Contact the author

Keywords

wine microbiology, light-struck taste, yeasts

Citation

BIOPROTECTION BY ADDING NON-SACCHAROMYCES YEASTS : ADVANCED RESEARCH ON THIS PROMISING ALTERNATIVE TO SO₂

Sulphur dioxide has been used for many years for its antimicrobial, antioxidant and antioxydasic properties in winemaking but nowadays, it is a source of controversy. Indeed, consumers are more attentive to the naturalness of their foods and beverages and the legislation is changing to reduce the total SO₂ levels allowed in wines. To limit and replace the doses of sulphur dioxide applied, winemakers can now use bioprotection consisting in live yeast addition as alternative,seems to be promising. This process, lightly used in from the food industry, allows to colonize the environment and limit the development or even eliminate undesirable microorganisms without altering the sensory properties of the product.

Perception of Rose Oxide Enantiomers, Linalool and α-Terpineol to Gewürztraminer Wine Aroma

Monoterpenes are important aroma compounds in white wines. Many monoterpenes are chiral and the chiral forms have different aroma qualities.

Tracking innovations for glyphosate-free in sloppy or terraced vineyard

Context and purpose of the study. Reducing pesticide use such as glyphosate, is a key challenge to support sustainability of viticulture systems and resilience of vineyard.

Bioprotective non-Saccharomyces yeast as an alternative to sulfites for the winemaking process

Sulfur dioxide (SO2) is used in winemaking due of its antioxidant, antioxydasic and antiseptic properties. Excessive amount of SO2 can negatively impact wine sensory perception and be detrimental for health. Agri-food industries are more transparent towards consumers concerning addition of sulfites, and oenology is no exception in this clairvoyance. As a consequence, the increase of consumers preference for wine with low or absent of sulfites addition is notorious. In this context, the impact of low/zero sulfites winemaking process on the microbial community should be evaluated. Moreover, microbial agents corresponding to bioprotective cultures represent a growing interest as an alternative to sulfites preservation in the early stages of vinification. However, scientific studies conducted to demonstrate their real effect are almost rare.

Heatwaves and grapevine yield in the Douro region, crop model simulations

Heatwaves or extreme heat events can be particularly harmful to agriculture. Grapevines grown in the Douro winemaking region are particularly exposed to this threat, due to the specificities of the already warm and dry climatic conditions. Furthermore, climate change simulations point to an increase in the frequency of occurrence of these extreme heat events, therefore posing a major challenge to winegrowers in the Mediterranean type climates. The current study focuses on the application of the STICS crop model to assess the potential impacts of heatwaves in grapevine yields over the Douro valley winemaking region. For this purpose, STICS was applied to grapevines using high-resolution weather, soil and terrain datasets over the Douro. To assess the impact of heatwaves, the weather dataset (1989-2005) was artificially modified, generating periods with anomalously high temperatures (+5 ºC), at certain onset dates and with specific durations (from 5 to 9 days). The model was run with this modified weather dataset and results were compared to the original unmodified runs. The results show that heatwaves can have a very strong impact on grapevine yields, strongly depending on the onset dates and duration of the heatwaves. The highest negative impacts may result in a decrease in the yield by up to -35% in some regions. Despite some uncertainties inherent to the current modelling assessment, the present study highlights the negative impacts of heatwaves on viticultural yields in the Douro region, which is critical information for stakeholders within the winemaking sector for planning suitable adaptation measures.