Research Mission

Current research focuses on fruit quality. Extensive work involving flavor precursors may one day allow for enumeration of individual influences on wine quality, and ultimately reveal exactly how terroir affects wine quality. Further, this work could eventually produce a system for correlating grape quality with wine quality.

Wine quality is, in large measure, determined by the grape and the winemaker. Fruit characteristics are governed principally by the terroir, that combination of soil and climate influencing grape chemistry and subsequent wine quality. Overlaid on the basic quality derived from the grape is the mark of the winemaker. A skillful winemaker, therefore, is one who can adjust product variables in such a way as to emphasize one or more aromas, flavors or textures to produce a well-balanced, integrated product.

The debate between the relative importance of terroir compared to winemaking technology is both old and ongoing. Terroir is a curious French concept, a much discussed-term encompassing the total natural environment of any viticultural site. This environment includes climate (temperature and rainfall), sunlight energy, relief (altitude, slope and aspect), geology, pedology, and soil-water relationships. Opinions differ greatly on the reality and the possible importance of terroir in determining wine quality. However, any wine lover who has observed the fog in Napa, chalk in Champagne, clay in Virginia's Piedmont, or sand on the eastern shore of Virginia, can easily imagine the importance of terroir.

Major regional classifications of European vineyards have been largely based on the concept of terroir. Some new world viticulturists and researchers, however, have tended to dismiss it as a product of commercial interest, mysticism or both. For all the romantic appeal, the perception of terroir as the only major force in wine quality has been overstated. While fairly nonintrusive winemaking is the industry norm, the "God makes wine and all we do is go to the bottle shop" school of thought can result in some very ordinary products.

We have placed a great deal of importance on wine technology. Since 1986, Virginia Tech has conducted over 60 seminars/symposiums on topics ranging from "alternative varieties," wine analysis, wine stability, to Methode Champenoise production, and published numerous bulletins. It can be said that the improvements in grape growing and winemaking technology, by raising wine standards, have in some cases obscured differences in quality that may have been previously attributed to terroir. This same improvement in technology, however, focuses on terroir differences by eliminating or muting extraneous odors and flavors derived from less-than-optimal grape growing and winemaking, and allowing for a more true expression of the grape.

At Virginia Tech's Enology-Grape Chemistry Laboratory we are working in conjunction with colleagues at other research institutes on a method to evaluate an aspect of terroir. This procedure allows for the quantification of grape glycosides, in part aroma and flavor components.

In our quest to help the Virginia wine industry produce the highest quality products, we have had numerous discussions about how to define the abstract concept of wine quality. We know that the highest quality wines are a small group that are distinguished by refinement, complex aromas and flavors, fullness and concentration of flavors, and a lingering finish.

Wine quality is, in part, governed by grape quality. As such, grape growers practice "viticultural winemaking," an understanding that vineyard management influences grape quality and the quality of the wine produced. For example, we know that fruit quality is affected by all of the features of terroir. Unfortunately, the influences of each individual vineyard management practice are difficult to quantify.

Establishing a system in which growers are rewarded in proportion to the value of wine produced from their fruit has long been an industry goal. Traditional grape quality indicators such as sugar, acid and pH are largely ineffective because they are not good predictors of potential wine quality. Indeed, grape prices are often determined not by quality, but supply and demand.

There are important grape quality issues which need to be addressed if our industry is to reach its full potential. For example, are grapes grown on a particular trellis system of higher quality and if so, how much higher? High enough to warrant the cost of conversion of the system? Virginia has six viticultural areas. What, if any, are the differences in wine quality between the regions? Our research has demonstrated that selective fruit zone leaf removal reduces the incidence of fruit rot, increases color and possibly adds complexity. How can these benefits be quantified so that growers can justify their added management costs?

Answering these questions requires an objective measure of grape quality that correlates well with the quality of wine produced from those grapes, independent of winemaking techniques. At the Enology-Grape Chemistry laboratory at Virginia Tech, we are working on such a system. A system to measure certain groups of aroma/flavor precursors may be an objective measure that we hope to be able to correlate to wine quality. We hope that this method of indexing will help allow the Virginia wine industry to realize its full potential.

There are some who would suggest that we should not examine terroir too closely. After all, a fine symphony is merely a collection of notes. Terroir can also be considered the integration of all the input which influences the character of the grape. If we can finally dissect these influences, terroir may lose its romantic appeal while at the same time provide a degree of understanding, clarity and perhaps even better Virginia wines--the ultimate goal.

Current Research Projects

1. Effect of wine closures on head space volatiles of Sauvignon blanc.
2. Effects of thermal vinification on red wine quality.
3. The sensory effects of 10 Brettanomyces intermedius strains in red wines.
4. Defining appropriate crop loads for optimizing profitability and grape and wine quality.
5. Nitrogen status of grape juice as an indicator of wine quality.
6. Effect of training system on Viognier, Cabernet Franc and Traminette fruit components and wine quality.
7. Effect of ethanol sprays on Cabernet Sauvignon fruit maturity and grape and wine quality.
8. Effect of extended cold soak on Cabernet Sauvignon wine quality.