Profiling Potentially Smoke Tainted Red Wines: Volatile Phenols and Aroma Attributes

  • M. McKay Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch
  • F.F. Bauer Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch
  • V. Panzeri Institute for Grape and Wine Sciences, Stellenbosch University, Stellenbosch
  • L. Mokwena Central Analytical Facility, Stellenbosch University, Stellenbosch
  • A. Buica Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch

Abstract

Malodourous compounds, including volatile phenols (VPs) are frequently found at concentrations below their odour thresholds in wine, and may therefore be considered to present no threat to wine quality. Most investigations into smoke taint quantify compounds by chemical/analytical means, or investigate sensory effects of supra- and peri-threshold contamination in model wine. In this project, twelve wines (submitted by the South African industry as potentially smoke tainted) were screened for VPs using GC-MS, and characterized using descriptive analysis (DA) by a sensory panel highly trained in smoke taint evaluation.  Results were compared statistically to elucidate relationships between chemical and sensory characteristics.  It was demonstrated, using the combined dataset that concentration and composition of VPs in the wines correlated well with certain sensory attributes. Guaiacol was present in most samples at peri- or suprathreshold
levels, but was not correlated with taint unless in combination with other phenols, in which case it was associated with ‘smoky’, ‘ashy’ and ‘herbaceous’ attributes. Wines with supra-threshold levels of VPs showed negative attributes (‘chemical / plastic’, ‘tar / BR’ and ‘medicinal / Elastoplast™’). In some cases, sensory effects (‘earthy / dusty / potato skin’, ‘mouldy / musty’ and ‘cooked vegetables (veg.)’) could not be attributed to supra-threshold VP contamination, and therefore seemed to be due to combinations of VPs at subthreshold levels. Associations between negative attributes and historical bushfire events prior to harvest were found for a number of the wines. This study emphasizes the importance of understanding effects of VPs on wine aroma, and escalating awareness and sensitivity to these issues in the wine industry.

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Author Biographies

M. McKay, Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch
Lecturer in Oenology
F.F. Bauer, Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch
Professor in Wine Biotechnology
V. Panzeri, Institute for Grape and Wine Sciences, Stellenbosch University, Stellenbosch
Technical Officer in Sensory Science
L. Mokwena, Central Analytical Facility, Stellenbosch University, Stellenbosch
Analyst in Central Analytical Facility, Stellenbosch University
A. Buica, Department of Viticulture and Oenology; Stellenbosch University, Stellenbosch
Rresearcher in Oenology

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Published
2019-07-29
Section
Articles