WINETECH Technical Yearbook 2021

OENOLOGY RESEARCH | MAY 2021

OVER THE YEARS, Pinotage has found its way into the South African and international market. Whether you like this style or not, coffee Pinotage is a well- represented style on the South African wine market. By just looking at the labels or the tasting sheets, many of these wines are described with coffee , mocha , or even chocolate notes, so consumers can easily pick the wines if they prefer this particular style. But is it really true? The coffee aroma in wines has already been associated to specific molecules, such as 2-furanmethanethiol (FMT) in Bordeaux wines (Tominaga et al ., 2000), and it is generally linked to the wine ageing in oak barrels and the wood piece size and level of toasting (Fourie, 2005; Fernández de Simón et al ., 2010). Is there a link between this molecule and the coffee aroma in Pinotage wines? Or is it part of a marketing strategy? To test this, we selected several Pinotage wines based on the same information available to any consumer: labels and tasting sheets. The sample set consisted of 15 wines, including two blind duplicates. Most of the wines were described by the producers with coffee/mocha/chocolate attributes, except for a few, which were purposefully chosen without these notes as control. The selected wines were evaluated

by a panel of trained judges using a rapid method; the samples were rated on a scale from 0 to 100 for the one attribute we were interested in: coffee aroma . At the same time, we measured the levels of FMT in the same wines (Mafata et al ., 2018). The results from the chemical analysis and the rating exercise were put together to determine whether the concentrations of FMT and the intensity of the coffee aroma perception were correlated. Lastly, perceived intensity of coffee aroma was correlated with the number of coffee or coffee-related attributes found on the front and back labels of the selected wines. As can be seen from table 1, the level of FMT covers a wide range, from 6 to 138 ng/L. There are three wines which stand out through their very high level of this compound, namely 133 to 138 ng/L (PT4, PT6 and PT9), while most of the wines are in the 20 to 40 ng/L range. Looking at the other thiols, the wines are not very different from each other. All thiols are present above their odour thresholds. (More information about thiol profiles of various cultivars were presented in the article “Thiol profiles of single cultivar red wines” published in the December 2018 edition of WineLand. ) CHEMISTRY RESULTS

ASTRID BUICA, GONZALO GARRIDO-BAÑUELOS, MPHO MAFATA & VALERIA PANZERI: South African Grape and Wine Research Institute, Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch KEYWORDS: Coffee aroma, Pinotage wines, FMT. Is there a link between coffee aroma perception and the level of FMT in Pinotage wines?

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