Prof Wessel du Toit from the Department of Viticulture and Oenology in the Faculty of AgriSciences at Stellenbosch University recently delivered his inaugural lecture titled “My wine journey".
Du Toit spoke to the Corporate Communication and Marketing Division about how his work helps to improve the quality of wine so that consumers can fully appreciate its delightful fruity aromas.
Tell us more about your research and why you became interested in this field.
My research primarily focuses on the role of oxygen in wine and the impact of phenolic compounds (molecules in plants and wine) on red wines. Oxygen can influence the sensory and chemical characteristics of wine, both positively and negatively. Excessive exposure to oxygen can result in wine oxidation, causing it to develop aromas reminiscent of bruised apples or sherry. Conversely, insufficient oxygen can lead to a reductive state in the wine, characterised by undesirable odours resembling rotten eggs or stale water. Thus, the appropriate amount of oxygen required by wines necessitates a delicate balance to avoid either excessive oxidation or excessive reduction.
Phenolic compounds play a crucial role in shaping the taste and mouthfeel of red wines. They exhibit significant diversity and present challenges in terms of analysis. We have developed rapid methods for measuring their levels in grapes and wines, enabling us to gain insights into their effects on the sensory characteristics of wines.
During my first year at university, my father introduced me to two red wines made from the same vineyard but with different levels of phenolic compounds. I clearly recall that they had distinct flavours. This experience sparked my fascination with wine, specifically with phenolics in grapes and wines.
How would you describe the relevance of your work?
Oxidation and reduction aromatic faults continue to be prevalent issues at wine-tasting events. By comprehending the processes of oxidation and reduction in wine, we can enhance the quality of wine and minimize the negative impacts caused by these processes. Additionally, understanding and monitoring the extraction of phenolic compounds from red grapes during the production of red wines will contribute to higher-quality products. These advancements can potentially benefit wine producers by reducing costs and yielding superior wines.
As many South Africans appreciate a glass of fine wine, my research aims to enhance their sensory experience. By preventing excessive oxidation or excessive reduction, consumers can fully appreciate the delightful fruity aromas present in the wine. Furthermore, a deeper understanding of phenolic compounds in red wines allows the production of wines that are less bitter and astringent, while still maintaining a full-bodied character when desired.
What aspects of your work do you enjoy the most?
I love to see some of my old students, both undergraduates and postgraduates, performing well in the wine industry.
The higher education environment can sometimes be challenging. What keeps you motivated when things get tough?
I think my interest in science and especially wine. The latter is a very complex, but also mysterious beverage, which makes working with it even more enjoyable and interesting.
Tell us something exciting about yourself that people would not expect.
I make my own beer, olives, and boerewors at home, which don't taste too bad!
How do you spend your free time?
I enjoy spending time with my family. My two sons love to make wine with me at home. I also enjoy reading a good book on war or ancient cultures.