Macrowine 2021
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

Related articles…

A versatile genome editing platform for grapevine: improving biotic and abiotic stress resilience 

New Plant Breeding Techniques (NPBTs) have arisen with the objective of surmounting the constraints inherent in conventional breeding methodologies, thereby enhancing plant resilience against both biotic and abiotic stresses. To date the application of genome editing in grapevine is still limited by the necessity to overcome recalcitrance to produce embryogenic calli and to regenerate plants. In our studies, we developed a smart and versatile genetic transformation system carrying all the most promising features of different genome editing approaches. In specific, we joined the GRF-GIF expression to improve regeneration, the systemic movement of the editing transcripts through tRNA-like sequences (TLS) and the cisgenic-like approach to remove transgenes.

Innovative sparkling wines, traditional grape varieties and autochthonous yeasts: emerging trends for regional products diversification

Italy, like all the major vine-growing and wine-producing countries, has experienced a decline in wine export volumes in recent years.

Nuove tecnologie per la viticoltura in zone di alto valore ambientale

Gli autori presentano gli ultimi risultati delle ricerche dei DIAF sulla meccanizzazione delle operazioni colorali in zone di difficile accesso e transitabilità quali le aree marginali, i terreni terrazzati e altre realtà agricole caratterizzate da spazi estremamente ristretti (vivaismo, orticoltura, ecc.).

ANTHOCYANINS EXTRACTION FROM GRAPE POMACE USING EUTECTIC SOLVENTS

Grape pomace is one of the main by-products generated after pressing in winemaking.Emerging methods, such as ultrasound-assisted extraction with eutectic mixtures, have great potential due to their low toxicity, and high biodegradability. Choline chloride (ChCl) was used as a hydrogen bond acceptor and its corresponding hydrogen bond donor (malic acid, citric acid, and glycerol: urea). Components were heated at 80 °C and stirred until a clear liquid was obtained. Distilled water was added (30 % v/v). A solid-liquid ratio of 1 g pomace per 10 ml of eutectic solvent was used.

δ13C : A still underused indicator in precision viticulture  

The first demonstration of the interest of carbon isotope composition of sugars in grapevine, as an integrated indicator of vineyard water status, dates back to 2000 (Gaudillère et al., 1999; Van Leeuwen et al., 2001). Thanks to the isotopic discrimination of Carbon that takes place during plant photosynthesis, under hydric stress conditions, it is possible to accurately estimate the photosynthetic activity. Ever since, δ13C has been widely applied with success to zonation, terroir studies and vine physiology research, but is still not widely used by viticulturists. This is quite astonishing by considering the impact of global warming on viticulture and the need to improve water management, that would justify a widespread use of δ13C.
The lack of private laboratories proposing the analysis, the cost of the technology, as well as the long analytical delays, have been detrimental to its development. Some laboratories tried to overcome the analytical difficulties of isotopic analysis by using fourier transformed infrared spectroscopy, as a fast and cheap alternative to the official OIV method (IRMS). These claimed FTIR models have never been published or peer reviewed and cannot be considered robust. In this work, thanks to the recent acquisition of IRMS technology, new modern and robust applications of δ13C for viticulture are proposed. This includes the use of the analysis to make parcel separations at harvesting, the possibility to increase the precision of hydric stress cartography and the potential cost reduction when compared with Scholander pressure bomb analysis.