Smoke-derived Taint in Wine: Effect of Postharvest Smoke Exposure of Grapes on the Chemical Composition and Sensory Characteristics of Wine

Abstract

Although smoke exposure has been associated with the development of smoke taint in grapes and subsequently in wine, to date there have been no studies that have demonstrated a direct link. In this study, postharvest smoke exposure of grapes was utilized to demonstrate that smoke significantly influences the chemical composition and sensory characteristics of wine and causes an apparent 'smoke taint'. Verdelho grapes were exposed to straw-derived smoke for 1 h and then fermented according to two different winemaking treatments. Control wines were made by fermenting unsmoked grapes. Sensory studies established a perceivable difference between smoked and unsmoked wines; smoked wines were described as exhibiting 'smoky', 'dirty', 'earthy', 'burnt' and 'smoked meat' characteristics. Quantitative analysis, by means of gas chromatography-mass spectrometry, identified guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, eugenol, and furfural in each of the wines made from smoked grapes. However, these compounds were not detected in the unsmoked wines, and their origin is therefore attributed to the application of smoke. Increased ethanol concentrations and browning were also observed in wines made from grapes exposed to smoke.

The effect of winemaking techniques on the intensity of smoke taint in wine

“…The most intense smoke-related attributes were perceived in smoked wines made with AWRI 1176, ICV D254, BDX and S6U; in the current study, this could be correlated with increased guaiacol and guaiacol glycoconjugate levels. This is in agreement with previous studies that attributed the 'smoky', 'phenolish', 'ash', 'burning wood' and 'burnt' aromas of smoke-tainted wines with increased levels of guaiacol and 4-methylguiacol following grapevine exposure to smoke (Kennison et al 2007, Hayasaka et al 2010a). Based on the descriptive sensory analysis results, the yeast strains most capable of reducing 'smoke' aroma and flavour, without compromising 'fruit' characters were AWRI 1503, ICV GRE, AWRI Fusion and SIHA active 3.…”

“…CIELAB colour coordinates provided more complex colour measurements and, when subjected to PCA, facilitated separation of smoked rosé style wines (but not red style wines) by the value of a* and hueab (data not shown). This is consistent with the increased brown hue observed in smoked Verdelho wines from Kennison's (2007) previous work. Guaiacol and 4-methylguaiacol were not detected in either control or smoked Grenache fruit, but elevated levels of guaiacol glycoconjugates were observed in smoked fruit, compared with control fruit.…”

“…While grapevine exposure to smoke has been shown to affect wine composition and can enhance the perception of smokerelated sensory attributes (Kennison et al 2007(Kennison et al , 2008(Kennison et al , 2009, the potential amelioration of smoke taint has not been investigated. This study was therefore undertaken to investigate the efficacy of various winemaking techniques in reducing the intensity of smoke-related sensory attributes, while maintaining Each value is the mean score from one wine replicate presented to 13 judges in three replicate sessions.…”

“…Recent research has established that grapevine exposure to smoke from bushfires or prescribed burning can result in smoke-tainted grapes and wine (Kennison et al 2007, 2009, Sheppard et al 2009). Kennison et al (2007) reported the presence of several volatile phenols (including guaiacol and 4-methylguaiacol) and objectionable 'smoke' characters in wines made from grapes exposed to smoke post-harvest, but not in control wines made from unsmoked grapes.…”

“…Kennison et al (2007) reported the presence of several volatile phenols (including guaiacol and 4-methylguaiacol) and objectionable 'smoke' characters in wines made from grapes exposed to smoke post-harvest, but not in control wines made from unsmoked grapes. In subsequent field-based experiments, guaiacol and 4-methylguaiacol were identified in grapes (Sheppard et al 2009) and wines (Kennison et al 2009) following the application of smoke to grapevines at several different phenological growth stages.…”