IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Smoke taint: Understanding and addressing the compositional consequences of grapevine exposure to smoke

Smoke taint: Understanding and addressing the compositional consequences of grapevine exposure to smoke

Abstract

Climate change has become a major challenge for grape and wine production around the world. Grapegrowers and winemakers are not only affected by increasing temperatures and prolonged drought, but by vineyard exposure to bushfire/wildfire smoke, which can taint grapes and wine, causing significant revenue losses where unpalatable smoky, ashy characters render wine unsaleable. Considerable research has therefore been undertaken over the past ~20 years to understand the compositional and sensory consequences of grapevine exposure to smoke. 

Early studies measured guaiacol and 4-methylguaiacol as markers of smoke taint, because these compounds were oak volatiles (deriving from the thermal degradation of lignin during the toasting process of cooperage) known to impart smoke-related sensory attributes, and analytical methods existed for their quantitation in wine. Today, a suite of volatile phenols (guaiacols, cresols and syringols) are measured as smoke taint marker compounds – in both free and glycosylated forms.

Volatile phenols have been identified as constituents of smoke, and can be found in grapes immediately after smoke exposure, but are rapidly glycosylated, giving volatile phenol glucosides, gentiobiosides, diglycosides and rutinosides. During fermentation, some glycoconjugates are hydrolysed by yeast and/or enzymes, releasing volatile phenols into wine. However, a significant portion of the glycoconjugate pool remains after winemaking, and can contribute to the sensory perception of smoke taint due to in-mouth hydrolysis. Ideally, smoke taint risk assessments should therefore comprise determination of both volatile phenols and volatile phenol glycoconjugates, either directly (by GC-MS and LC-MS/MS, respectively) or indirectly (by GC-MS, before and after acid or enzyme hydrolysis).

The detection/evaluation of smoke taint is further complicated by the natural occurrence of some volatile phenols (and their glycoconjugates) in the fruit (and therefore wine) of some grape varieties, without smoke exposure, for example Shiraz and Petit Sirah. Research is therefore underway to establish the varietal, regional and temporal variation in naturally-occurring volatile phenol glycoconjugate concentrations, to better inform decision-making in the lead up to vintage, where vineyards are potentially impacted by smoke. 

This presentation will provide an overview of the chemistry of smoke taint, the analytical methods available for determination of smoke taint, and the latest strategies for mitigation and amelioration of smoke taint in grapes and wine. 

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Professor Kerry Wilkinson¹

¹ Department of Wine Science, Waite Research Institute, The University of Adelaide, Australia

Contact the author

Keywords

grapes, glycosylation, smoke taint, volatile phenols, wine

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

Directed Evolution of Oenococcus oeni: optimising yeast-bacteria interactions for improved malolactic fermentation

Malolactic fermentation (MLF) is a secondary step in the vinification process and it follows alcoholic fermentation (AF) which is predominantly carried out by Saccharomyces cerevisiae. These two processes result in the degradation of metabolites to produce secondary metabolites which also contribute to the final wine flavour and quality. AF results in the production of ethanol and carbon dioxide from sugars and MLF stems from the degradation of L-malic acid (a dicarboxylic acid) to L-lactic acid (a monocarboxylic acid). The latter process results in a smoother texture as the acidity of the wine is reduced by the process, it also adds to the flavour complexity of the wine.

Read More

The application of soil biological indicators to support soil conservation practices and landscape quality in viticulture

Le but de notre travail a été d’étudier l’influence de différents systèmes de la gestion du sol en viticulture sur des paramètres biologiques de sol comme indicateurs de la protection et de la qualité du sol. La conservation de sol est indispensable pour une viticulture durable et la protection du terroir. Nos résultats ont montré, que la matière

Read More

Varietal volatile patterns of Italian white wines

Aroma diversity is one of the most important features in the expression of the varietal and geographic identity and sensory uniqueness of a wine. Italy has one of the largest ampelographic heritages of the world, with more than five hundred different varieties. Among them, many are used for the production of dry still white wines, many classified as Protected Designation of Origins and therefore produced in specific geographical areas with well-defined grape varieties. Chemical and sensory characteristics of the aroma of these wines have never been systematically studied, and the relative diversity has never been described and classified.

Read More

Outils de caracterisation et zonage des paysages viticoles: application aux vignobles français

Un paysage viticole est une relation entre des formes, dimension objective, et la perception que nous en avons, dimension subjective, émotionnelle. La viticulture n’est pas seulement productrice d’un vin, elle contribue également à façonner le paysage. Pourtant, jusqu’à présent, la connaissance des terroirs était principalement basée sur la caractérisation de leur aptitude à produire des vins de qualité.

Read More

Use of artificial intelligence for the prediction of microbial diseases of grapevine and optimisation of fungicide application

Plasmopara viticola, the causal agent of downy mildew (DM), and Uncinula necator, the causal agent of powdery mildew (PM), are two of the main phytopathogenic microorganisms causing major economic losses in the primary sector, especially in the wine sector, by wilting bunches and leaves with a consequent decrease in the photosynthetic rate of the plant and in the annual yield. Currently, the most widespread methods for planning spraying are based on the 3-10 rule, which states that the first application should take place when: (i) the air temperature is greater than 10°C; (ii) shoots are equal or greater than 10 cm; and (iii) a minimum of 10 mm rainfall within 24–48 hours has occurred, or at the beginning of the bud break with periodic applications according to the manufacturer’s instructions.

Read More