Enoforum 2021
IVES 9 IVES Conference Series 9 Enoforum Web 9 Enoforum Web Conference 2021 9 Influence of pre-fermentative steps on varietal thiol precursors

Influence of pre-fermentative steps on varietal thiol precursors

Abstract

The content of 3-sulfanyl-1-hexanol and its acetate ester in wine is affected by a number of factors, including the concentration of its precursors S-3-(hexan-1-ol)-L-glutathione (G-3SH), S-3-(hexan-1-ol)-L-cysteine (Cys-3SH) and S-3-(hexanal)-glutathione (G-3SHal) in the grape must. The role of grape must extraction steps on the content of volatile thiol precursors (VTP) in must fractions was investigated.

Grillo grape must samples were drawn along with the grape must extraction process in a winery under either air-exposed or air-free conditions, as well as under laboratory conditions and their VTP and glutathione (GSH) content was assessed by UPLC-HRMS. The roles of copper ions and sulfite were also investigated.

Under industrial conditions, more than 95% of the grape G-3SHal was lost following to the grape crushing due to sulphite addition. The content G-3SH and Cys-3SH increased with the must yield, specially under air-exposed conditions, while the GSH level decreased. Under laboratory conditions, trace amount of 3-SHal was obtained when air-free condition was applied or sulfite was added, instead milligrams per litre levels were obtained if air-exposed condition was applied, especially (14.5 mg/L) when copper sequestering salts were added. Negligible amounts of GSH (as well as grape reaction product) were detected in all the laboratory-made samples except when sulphite was added (GSH=33 mg/L).

The data strongly suggest that G-3SHal in grape must is mainly produced along with must extraction following to the binding of GSH to (E)-2-hexenal which is readily reduced to G-3SH. Sulfite addition strongly prevents the VTP formation, as well as copper ions. Therefore, grape must extraction must be considered among the main factors affecting the VTP content in grape must.

DOI:

Publication date: April 23, 2021

Issue: Enoforum 2021

Type: Article

Authors

Daniela Fracassetti, Ivano De Noni, Milda Stuknytė, Valentina Pica, Antonio Tirelli

Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, Via G. Celoria 2, Milan, Italy

Contact the author

Tags

Enoforum 2021 | IVES Conference Series

Citation

Related articles…

“Terroir” and grape and wine quality of native grape variety Istrian Malvasia

Viticulture and wine production have a historical tradition in Istria. First written document of vine cultivation in this area date since antiquity. The most wide spread vine variety in Istria is Istrian Malvasia (white variety), and it capture about 60% of total vineyard surface in Istria today.

Clustering wine aromatic composition of Vitis vinifera grapevine varieties

Climate change is likely to impact wine typicity across the globe, raising concerns in wine regions historically renowned for the quality of their terroir. Amongst several changes in viticultural practices, replacing some of the planting material (i.e clones, rootstocks and cultivars) is thought to be one of the most promising potential levers to be used for adapting to climate change. But the change of cultivars also involves the issue of protecting the region’s wine typicity.

Mitigation of retronasal smoke flavor carryover in the sensory analysis of smoke affected wines

With the steady rise in wildfire occurrence in wine regions around the world, there are quality issues beginning to face the wine industry. These fires produce clouds of smoke which have the ability to carry organic molecules across vast distances that can be absorbed by grapes. When these compounds make their way into the final wine, unpleasant smokey and burnt flavors are present, along with a lasting ashy finish. Along with the volatile compounds carried by smoke, once incorporated into the fruit these compounds become bound to sugars, forming glycosidic compounds.

Modification on grape phenolic and aromatic composition due to different leafroll virus infections

Viral diseases are reported to cause several detrimental effects on grapevine. Among them, leafroll, due to single or mixed infection of GLRaV1 and GLRaV3, and rugose wood, associated to GVA, are considered the most widespread and dangerous.

The impact of global warming on Ontario’s icewine industry

Ontario’s wine regions lie at the climatic margins of commercial viticulture owing to their cold winters and short cool growing season. The gradual warming of northern latitudes projected under a human-induced climate change scenario could bring mixed benefits to these wine regions.