Department of Viticulture and Oenology

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Browsing Department of Viticulture and Oenology by Author "Alessandri, Anne"

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    Polycyclic Aromatic Hydrocarbons: potential sources from the vineyard and analysis in wine
    (Stellenbosch : Stellenbosch University, 2016-12) Alessandri, Anne; McKay, Marianne; Strever, Albert; Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology.
    ENGLISH ABSTRACT: The South African wine industry plays an important role in the economy, contributing R36.1 billion gross domestic product (GDP) to the regional economy and employing 300 000 people both directly and indirectly in 2013. In order to build on this, the local industry continues to align itself to international trends and expectations. At the same time, polycyclic aromatic hydrocarbons (PAHs) are under continued scrutiny for their impact on the environment and health, due to their mutagenic and carcinogenic properties. There has been some concern that grapes grown in South African vineyards may be exposed to various sources of PAH contamination. These sources of contamination include the usage of creosote posts in vineyards, bush fires and vehicle emissions, as well as the use of charred barrels in the cellar. The aim of this study was to determine if the exposure to PAHs resulted in the presence of PAHs in wine, and at which levels they may be present in wine. Chapter 3 compared the use of the Ultra high-pressure liquid chromatography coupled with Fluorescence detection (UPLC-FLD) and the High-pressure liquid chromatography coupled with Fluorescence detection (HPLC-FLD) system for the analysis of PAHs in wine. Wine samples were extracted using the liquid-liquid extraction method developed by Panzeri (2013). It was found that both methods were suitable for low level PAH analysis, with the UPLC-FLD detector being faster. In chapter 4, a selection of South African and international wines were analysed to determine the levels of PAHs found in the wines. The wines analysed had been randomly selected, from different regions, cultivars and vintages. Some wines had been made from grapes grown in vineyards using creosote posts for trellising and some were bush vines with no posts used at all. Some of the wines had been fermented or aged in oak barrels, while some had no wood treatment. The result of the analysis was that the majority of the wines selected had very low levels of PAHs. The levels were not high when compared to the legal limits set by the European Union of 1 ppm B[a]P for all dietary food (European Directive 2006/125/EC). The quantities of PAHs found in the wine samples were all below 2 ppb, which is the guideline set by AFFSA, the French Agency for Food, Environmental and Occupational Health & Safety (AFFSA, 2006). There were no differences between the PAH levels in South African and international wines. Some wines analysed had levels of PAHs higher than the legal limit allowed in water of 0.01 μg/L for B[a]P and 0.1 μg/L for the sum of B[b]F, B[k]F, B[ghi]P and Ind[1, 2, 3-cd]P (European Directive 2006/125/EC). This was potentially due to an accumulation of contamination from various sources – creosote, vehicle emissions, exposure to smoke from bush fires and extended barrel aging. By eliminating creosote posts in the vineyard, avoiding bush fires just before harvest, as well as monitoring the use of charred oak barrels, the PAH levels should be reduced to levels below the legal limits in water. Further work could include looking at vineyards with high levels of PAHs in the soils and investigate how to reduce or remove the PAHs. The degradation of PAHs in wine over time could also be monitored.