Determination of Volatile Phenol in Cabernet Sauvignon Wines, Made from Smoke-affected Grapes, by using HS-SPME GC-MS

Abstract

The increased incidence of vegetation fires near vineyards in the Western Cape, South Africa has led to growing concern over the appearance of smoke taint in the affected grapes. This study focused on the effect of smoke exposure on the volatile phenol (VP) composition of wines made from affected grapes over two vintages (2012 and 2013). Cabernet Sauvignon grapes were exposed, 10 days post-véraison, to a single, hour-long treatment with smoke derived from burning a mixture of vegetation (including fynbos) under controlled conditions in enclosures. Enclosures were sealed for 24 h after exposure, and then removed. Grapes were allowed to ripen and wines were then produced. Wines were analysed by headspace gas chromatography mass spectrometry (HS-SPME GC-MS) for selected volatiles. The results of the investigation show that the exposure of grapes to smoke during ripening leads to the accumulation of VPs that were detected in wines. The detected VPs were guaiacol, phenol and the cresols. Smoke exposure of grapes during ripening may have a negative impact on wine quality due to the accumulation of these compounds.

Testing the Sensitivity of Potential Panelists for Wine Taint Compounds Using a Simplified Sensory Strategy

“…Samples of the blend (50 mL) were taken to determine the baseline levels of the compounds investigated in this study. Analysis of volatile phenols in the de-aromatized wine was performed following the method outlined by De Vries et al [ 43 ] using an Agilent Gas Chromatograph, model 6890N (Agilent, Palo Alto, CA, USA), coupled to an Agilent Mass Spectrometer 5975 B Inert XL EI/CI (Agilent, Palo Alto, CA, USA). Three technical repeats were analyzed for 13 volatile phenols (guaiacol; 2,6-dimethylphenol; 4-methylguaiacol; o -cresol; phenol; 4-ethylguaiacol; m -cresol; p -cresol; 2,3-dimethylphenol; eugenol; 4-ethylphenol; 4-vinylguaiacol; and 3,4-dimethylphenol).…”

Comparison of an Offline SPE–GC–MS and Online HS–SPME–GC–MS Method for the Analysis of Volatile Terpenoids in Wine

“…The aroma profile is attributed to a variety of compounds which can be separated into various classes based on their chemical structure [2]. Selected classes include esters ('fruity'/'floral') [3], fatty acids ('rancid') [4,5], C 6 alcohols and aldehydes ('leafy', 'green') [6], methoxypyrazines ('green capsicum') [7], varietal thiols ('grapefruit', 'guava', 'granadilla') [8], volatile phenols ('smoke') [9], reductive sulfur compounds ('cabbage') [10], lactones ('wood') [11], carbonyl compounds ('creamy') [12], and terpenoids ('floral') [2,13]. In the context of this work, terpenoids and C 13 norisoprenoids are of particular importance, as they contribute to some highly desirable descriptors such as 'floral', 'raspberry', 'tobacco', 'honey', and 'citrus' notes [14].…”

Classification of Smoke Contaminated Cabernet Sauvignon Berries and Leaves Based on Chemical Fingerprinting and Machine Learning Algorithms

“…Bushfires that occur near wine regions can result in grapevine smoke exposure, which can alter the chemical composition of grape berries. Wine produced from these smoke-affected grapes may exhibit unpalatable smoky aromas and flavors, such as “burnt wood”, “ashy”, and “burnt rubber” [ 6 , 7 , 8 , 9 ]. These undesirable characters have been attributed to smoke-derived volatile phenols (VPs), including guaiacol, 4-methylguaiacol, cresols, and syringol [ 7 , 10 , 11 ].…”

“…Wine produced from these smoke-affected grapes may exhibit unpalatable smoky aromas and flavors, such as “burnt wood”, “ashy”, and “burnt rubber” [ 6 , 7 , 8 , 9 ]. These undesirable characters have been attributed to smoke-derived volatile phenols (VPs), including guaiacol, 4-methylguaiacol, cresols, and syringol [ 7 , 10 , 11 ]. It is thought that these VPs accumulate primarily in the skin of grape berries following smoke exposure and, to a lesser extent, in the pulp and seeds [ 12 , 13 , 14 , 15 ].…”