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10/10/2014

UC Davis seminar highlights colour and tannin management practices

A seminar on ‘red wine production strategies’ presented by the UC Davis Department of Viticulture and Enology in June provided an overview of current knowledge and research on wine production practices and their effects on phenolic extraction and wine quality.

Dr Anita Oberholster, UC Davis extension enologist, was one of the speakers and provided an overview of wine phenolic chemistry.

As reported in US Wine Business Monthly, Oberholster said phenolics are important because they are major contributors to wine quality attributes including colour, aroma, taste, flavour, body and texture.

“Phenolics also contribute to wine stability and ageing potential,” she told listeners at the seminar. “The main red grape and wine phenols are flavonoids that contribute to colour and astringency.”

Dr James Kennedy, California State University professor and department chair specialises in tannin research and discussed the phenolic evolution from grapes to wine and their relationship to wine quality and human perception.

In terms of tannin development and grape composition, skin and seed tannins are produced pre-veraison, but anthocyanin synthesis and tannin maturation occur post-veraison. He said seed bitterness is reduced as the seed matures, but seen tannin gets more astringent as the seen ripens. “We don’t know why, but we think seed oxidation may be involved,” he said.

Other speakers at the seminar included:

  • Larry Lerno, UC Davis research enologist, who discussed results of a cold soak trial at the UC Davis winery with Cabernet Sauvignon held at 10C for five different time periods ranging from zero to 10 days, followed by standard fermentation;
  • Dr David Block, UC Davis Department of Viticulture and Enology chair, who discussed recent research done in the campus winery to evaluate the effects of fermentation temperature and pump-overs on tannin extraction with Cabernet Sauvignon;
  • Steve Peck. J. Lohr Vineyards and Winery red winemaker, who discussed phenolic analysis and management, and;
  • Corey Beck, Francis Ford Coppola Winery director of winemaking, who talked about using the Harbertson-Adams Assay as an in-house analysis for colour, tannin, total phenols and polymeric pigments.

A full report can be found in the September 2014 issue of US Wine Business Monthly.

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