"Rave on" at Davis

Wines & Vines, May, 1993

New things may be in store for the University of California's Davis Campus annual "RAVE" seminar. The third RAVE was held April 1. And like its predecessors it featured speakers from the Department of Viticulture and Enology only. Like earlier, it was one day only.

But in the offing is a possibility of future RAVES (acronym for "Recent Advances in Viticulture and Enology") being a two-day affair and utilizing a broader spectrum of Davis scholars, especially those closely connected with the vineyard industry, i.e. pathology, food chemistry and marketing.

This year's seminar was a bell-ringer. The greatest response, as might be expected, was for remarks on resveratrol (the heart-easing ingredient found in a table wine and, for that matter, unfermented grape juice). Equally riveting was the presentation on phylloxera, the grape root louse that has recently raised its ugly head (because AXR-1 was used for a lot of vineyards in Napa Valley and is not resistant to phylloxera, roughly half of Napa's vineyards will have to be replanted).

A rundown on the subject matter: welcomes by extensionists Jim Wolpert and Jim Lapsley and the chairman of the Department of Viticulture and Enology, Dr Linda Bisson. Her remarks on alternatives to Bentonite were followed by two reports from Australian-educated Roger Boulton on online fermentation measurements and a rapid small-scale tartrate stabilization process; winemaking and resveratrol by a new member of the V&E faculty--Andrew Waterhouse, the veteran in viticulture, Dr. Mark Kliewer, on the influence of rootstock and vine spacing on performance of Cabernet Sauvignon, followed by a Wolpert report on winegrape clones: long-term results of Chardonnay, Cabernet Sauvignon and Zinfandel and preliminary results of Pinot noir for champagne. Nick Dokoozlian reported on windbreaks on vegetative and reproductive growth of Chardonnay vines and Peter Christensen of the Parlier station talked on winegrape trellises for the San Joaquin Valley. Doug Adams talked about potassium deficiency and Andy Walker talked on breeding for phylloxera resistance and Wolpert summed up the day with field evaluation of rootstocks.

Prof. Waterhouse' remarks on resveratrol are as follows:

"The cause of the 'French Paradox' has been the subject of much speculation within and without the wine industry. Reynaud's study describing this "Paradox" has been supported by other studies that point to a lower heart disease rates for wine drinkers. Some discussion focuses on whether wine drinkers have better health than the general population for "lifestyle" reasons, or whether wine contains substances that reduce disease. Our research is focusing on determining whether substances in wine are likely to have a positive health impact, and if so, what are the effects.

"Leroy Creasy at Cornell has made the proposal that resveratrol is the wine constituent that reduces heart disease. Resveratrol is a chemical found in a traditional medicinal herb used in the Orient, and some lab studies have shown effects that can be correlated with reducing heart disease. This proposal has stimulated much interest in the compound, and we have been investigating several questions related to resveratrol.

"We have several investigations in progress. One is to study the levels of resveratrol in commercial wines. We requested wine samples from 200 wineries and got hack over 400 wines to test! One (now important) part of this study is to have an analysis procedure that is quick. Preliminary results suggest that there are clear differences between wines made from different grape varieties, although the levels are not what might be expected. Another project is looking at the effects of winemaking procedures on resveratrol levels including different fermentation procedures as well as the effects of fining and filtering agents.

"We are also using a lab test to screen for potentially beneficial compounds. Antioxidants are a group of chemicals that occur in all plants. Many diverse chemicals are antioxidants, and S|O.sub.2~ is a very important one in winemaking. Antioxidants are now being linked to reducing heart disease and cancer. We are working with another lab that has a procedure to quickly detect antioxidants and we are trying to determine which wine components have the most potential antioxidant action in wine consumers. We have already have seen that resveratrol has some good competition as an antioxidant."