WINETECH Technical Yearbook 2020

To measure the effects these thiols have on the sensory attributes in combination with each other, interaction experiments were ran between 3MH x 4MMP and 3MHA x 4MMP (Experiment 2). For each set, nine combinations of the levels (from zero x zero to high x high) were evaluated, using as base de-aromatised Pinotage. To determine the role the matrix plays in the perception of the compounds, addi­ tional interaction experiments were run between 4MMP x 3MH and 4MMP x 3MHA (Experiment 3). This time, de-aromatised Pinotage, Shiraz, Merlot and Cabernet Sauvignon were used as base wines. TAKE-HOME MESSAGE As a result, these extensive sensory exper- iments showed that complex interactions take place between thiols, thiols and other

on red wine aroma. From literature, we know that thiols have a significant impact on wine aroma. There is a lot of informa- tion available on white wine, especially Sauvignon blanc and more recently Chenin blanc, but very little on red wine. Due to the complex nature of the red wine matrix, there is a need for systematically elucidat- ing the contribution of thiols on the aroma of cultivars important for the South African wine industry. The results for Chenin blanc were presented in previous issues of Wine- Land (September and October 2018). Due to the extent and complexity of the exper- iments, the red wine investigation will be presented in a series of articles. REFERENCES Rigou, P., Triay, A. & Razungles, A., 2014. Influence of volatile thiols in the

development of blackcurrant aroma in red wine. Food Chemistry 142: 242-248. Doi: 10.1016/j.foodchem.2013.07.024. Mafata, M., Stander, M., Thomachot, B. & Buica, A., 2018. Measuring thiols in single cultivar South African red wines using 4,4-dithiodipyridine (DTDP) deri- vatization and ultraperformance conver- gence chromatography-tandemmass spec- trometry. Foods 7(9): 138. Doi: 10.3390/ foods7090138.

volatile compounds, and thiols and the wine matrix specific to a cultivar. We are only beginning to understand the role this class of compounds plays in red wine. What is clear though, is that, while single thiols can relatively easily be associated with spe- cific aromas, once present in combinations, the synergistic effects and the resulting complexity are still highly difficult to de - fine. Thiol presence in wine seems to be favourable depending on the desired style pursued by the winemaker, but the under- standing of the specific combination thiols x cultivar is of crucial importance given the vast difference of aromas associated with each unique combination. SUMMARY The most recent work done at DVO’s Sen - sory Unit sheds light on the impact of thiols

For more information, contact Valeria Panzeri at valeria.panzeri@icloud.com or Astrid Buica at abuica@sun.ac.za.

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