Anita Oberholster, Ph.D.
Associate Cooperative Extension Specialist, Enology
Viticulture and Enology
PhD from Adelaide University in Australia
Anita Oberholster completed her Ph.D. in Wine Sciences at the University of Adelaide, in Australia in 2008. She moved to the Department of Viticulture and Enology at UC Davis, in California, as a Cooperative Extension Specialist in 2011, from her role as a researcher in the Department of Viticulture and Oenology at Stellenbosch University in South Africa. In her current position, she focuses on continuing education for the grape and wine industry, while her research program concentrates on current issues in the grape and wine industry. Oberholster’s core research program focusses on two main parts: the influence of both viticultural practices and environmental factors on grape ripening and composition and related wine quality and investigations to determine the influence of different vinification practices on wine composition and quality. For the first part, the emphasis is specifically on tannin biosynthesis and polymerization, the main contributors to astringency and bitterness and carotenoid biosynthesis and break down products (the precursors of norisoprenoids), important volatile compounds with low olfactory thresholds. The impact of disease pressure and mechanization are also investigated. Since 2017, grape smoke exposure has become a main research area, investigating the absorption of volatile phenols on to grapes and the subsequent impact on wine composition and quality. The second core research focus, determining the influence of different vinification practices on wine composition and quality, includes studies to determine the influences of different cap management techniques, fermentation temperatures, and temperature differentials between cap and must temperature on extraction kinetics and thus wine composition. Additionally, the impact of oxygen (macro- and micro-oxygenation) and the presence of different hydrolysable tannins (barrel aging and oak alternatives) on phenol polymerization reactions and wine aging potential are investigated. The correlation between wine compositional changes and modifications in aroma, color, and mouth feel expression and thus quality of the wines are further explored.
Sustainability in both focus areas is important and alternative practices to enhance sustainability are being investigated, including the use of new technologies and ‘green’ chemicals in the winery and the re-use of winery wastewater for the irrigation of vines.