 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

The myth of the universal rootstock revisited: assessment of the importance of interactions between scion and rootstock

Aim‐ Rootstocks provide protection against soil borne pests and are a powerful tool to manipulate growth, fruit composition and wine quality attributes

Effect of the addition of polysaccharides extracted for grape pomace and must on sensory and chemical composition of white wines

AIM: The objective of this work is to study the effect of the addition of polysaccharides extracted for grape pomace by-products and musts on sensory and chemical composition of white wines. Much of the waste obtained in the wine sector is not used, and they can have some valuable compounds, such as the polysaccharides (PS).

Cinétique de développement de la Pourriture Noble dans différents terroirs des Coteaux du Layon : mise au point d’une méthodologie

Dans la région des Coteaux du Layon, en Maine et Loire, l’effet terroir et son déterminisme sont étudiés dans le cadre de la production des vins liquoreux.
Ces vins sont le résultat d’une maturité poussée au delà de celle prévue par la nature afin de donner aux baies une teneur en sucre et en matière sèche très forte, pour mieux valoriser ces effets de la surmaturation, les baies sont récoltées selon la méthode des tries successives (Asselin et al, 1996). Ainsi, on ne récolte à chaque passage que les grains ayant atteint le niveau de concentration requis pour obtenir des vins à fort degré d’alcool avec des sucres résiduels.

How pressing techniques affect must composition and wine quality of Pinot blanc

This study investigates how the sensory profile of Pinot Blanc is affected from different maceration and pressing techniques. Grapes were sourced from four vineyards in the village Tramin in South Tyrol. For the experiment 200 kg of grapes from each vineyard site were hand picked the day before harvest for the commercial winery took place. Grapes were stored over night at 4°C, homogenized and processed in the experimental winery at Laimburg research centre the day after harvest. Four different pressing techniques were applied in duplicates of 100kg each.

GC-O and olfactoscan approaches to reveal premature aging markers in Chardonnay wine

Molecular markers of wine oxydation, such as sotolon or Strecker’s aldehydes that induce respectively nut or curry and boiled vegetables or wilted rose odors, can be percieved as a default by consumers. These volatile compounds are especially formed during the premature aging of wine, but it is likely that several contributing compounds are still unknown as is their combined contribution. This study was carried out to identify the markers of oxydation in Chardonnay wine by Gas Chromatography Olfactometry (GC-O) and to study the impact of these markers on the complex wine aromatic buffer using the Olfactoscan approach.A Chardonnay wine (2018-vintage), taken after malolactic fermentation without sulphites addition, was submitted to an artificial oxidation to simulate more or less prononced premature oxidation. Volatile compounds were extracted by Solid-Phase Extraction (SPE) and analysed by GC-O with a panel of 13 trained subjects. The same extract was also submitted to a second analysis based on the Olfactoscan technique, which allowed to evaluate the impact of each volatile compounds on the complex aromatic buffer of a non-oxidized wine delivered as background odor. Preliminary results revealed three types of behavior. On the one hand, several odor zones appeared only with the background odour, suggesting a synergy effect induced by the compounds in the aromatic buffer. Conversely, odor-active compounds could not be perceived within the background odor suggesting a masking effect. Finally several compounds were found to contribute as key odorants for wine oxydation once mixed with the aromatic buffer. These compounds are still to be identified using complementary techniques.