WINETECH Technical Yearbook 2021

OENOLOGY RESEARCH | JANUARY/FEBRUARY 2021

Minimising volatile phenols in wine HEINRICH DU PLESSIS 1 , JUSTIN HOFF 1 , LUCKY MOKWENA 2 & NEIL JOLLY 1 : 1 Agricultural Research Council (ARC) Infruitec-Nietvoorbij, Stellenbosch; 2 Central Analytical Facilities (CAF), Stellenbosch University, Stellenbosch KEYWORDS: Yeasts, lactic acid bacteria, malolactic fermentation, chemical profile, wine style.

WINES PRODUCED FROM smoke-exposed grapes can exhibit unpleasant smoky, burnt or ashtray characteristics. This project investigated the effects that yeast selection, malolactic fermentation and wine style had on the volatile phenols associated with wines produced from smoke-exposed grapes. INTRODUCTION The occurrence of wildfires is increasing and affecting many wine-producing countries (United States of America, Spain, Chile, Australia and South Africa). Some of these fires are so devastating that entire vineyards and regions are destroyed. Besides the damage caused by these fires, the smoke that is produced in the vineyards or the surrounding areas could contribute to grapes and wines having an unpleasant, burnt and smoky character or palate, known as smoke taint (Kennison et al ., 2007). The compounds usually associated with this taint are known as volatile phenols (VPs), with characteristics ranging from sweet, smoky and toasty to ashtray, burnt and tar (Kennison et al ., 2007; McKay et al ., 2019). Guaiacol, 4-ethyl guaiacol, 4-methylguaiacol and 4-ethylphenol are the main VPs used as chemical ‘markers’ for the presence of smoke-tainted wine (Kennison et al ., 2007; Ristic et al ., 2011). These VPs and their

JULIAN SULLIVAN

WINETECH TECHNICAL YEARBOOK 2021 | 55