Mark West was working as a postdoc in the department of molecular and cellular biology at the University of California (UC), Davis, when he realized that he just wasn't happy doing research any more. He started thinking of different ways that he could use his scientific skills. Because he had worked with baker's and brewer's yeast, winemaking--a profession that relies on yeast genetics and fermentation--seemed like a logical alternative. "So I took a harvest position with Glen Ellen Vineyards and fell in love," he says.

In 6 short years, West moved from a harvest enologist position to that of head winemaker at Saintsbury, which is located in Carneros at the southern end of the Napa Valley. His advanced degree in biochemistry and a willingness to once again start at the beginning of a field helped him to move up the vineyard ladder rapidly.

Winemaking blends art with science and builds on a solid backbone of historical tradition; it is also very much a trade-oriented field. In the heart of California's central valley, professors at the department of viticulture and enology at UC Davis have taught budding winemakers and grape growers the scientific principles behind the trade for more than 120 years. Enology, the science of wine, and viticulture, the growing and management of the vines, are a combination of multiple subjects, including microbiology, chemistry, physics, and engineering. "Viticulture and enology challenge you to think across disciplines and integrate them in a way that we don't do in other sciences," says Roger Boulton, UC Davis Stephen Sinclair Scott professor of enology and chemical engineering.

The UC Davis program offers bachelor's, master's, and doctoral degrees, all concentrating on the art and craft of winemaking. Undergraduate students are encouraged to build on their scientific knowledge and their practical skills by working at a vineyard or laboratory while in school. UC Davis has two vineyards of its own, one in Davis and the other in Oakville, California. Students and faculty help run both facilities. And the vineyards of Napa Valley, Sonoma, and Alexander Valley aren't far away. After graduation, many of the bachelor's and master's students go to work as assistant winemakers at vineyards around the world.

Even so, a person doesn't need an enology degree to have a successful career at a winery, says Doug Adams, associate professor at UC Davis. Not if one is comfortable starting out as a harvest worker and moving up. Like West, someone with a strong research background will catch on to the science quickly and probably move rapidly up the vineyard management ranks.

Why do wineries need scientists? There are the obvious reasons: needing someone who can conduct quality-control experiments, culture yeast, and understand the intricacies of plant growth and development. There are also more abstract uses for people who think scientifically. "I use my scientific knowledge constantly but can't always explain how," West says. "I use it as a tool."

Smaller wineries often don't hire scientists on staff, mostly because they maintain tight control over the product and can taste every barrel and monitor most of the variables to ensure quality. Once a winery gets so large that the producers can't taste everything, however, analytical data can help maintain consistency. Using experimental technique and scientific theory lends a systematic approach to winemaking. So the larger wineries, such as Gallo, for instance, tend to hire more scientists. "At Gallo, Ph.D.s enter at every phase of production, from growing to winemaking to quality control," Adams says.

"Winemaking is all about science and chemical reactions," says Keith Emerson, assistant winemaker at Gundlach Bundschu Winery in the Napa Valley. Emerson graduated from UC Davis with a bachelor's degree in viticulture and enology in 1998. He started out as a cellarman and laboratory assistant at Cake Bread Cellars winery in the Napa Valley. Once he had learned the practical aspects of how a winery runs, he quickly landed a job as an assistant winemaker with Gundlach Bundschu.

Emerson performs experiments every day, from simple microscopy to acid tests, pH gauging, and using a spectrophotometer to check enzymatic reactions. And like any good graduate student or postdoc, he writes all of his results in a lab notebook and meticulously enters data into a winemaker database. Emerson and his fellow winemakers also attend two scientific meetings a year, one of which is sponsored by the American Society for Enology and Viticulture.

This season, in addition to producing the year's allotted quantity of wine, Emerson is working on yeast trial experiments. He and the head winemaker at Gundlach Bundschu are interested in how established yeast strains and newly developing strains affect wine flavor. For these experiments, he has three separate barrels, each with two tons of grapes and a different yeast strain. Each week, he and the head winemaker will observe the fermenting mixture by taste, smell, and composition to determine how the different yeast strains change the wine. They do these types of trials every harvest season, on different wine varieties, hoping that their taste buds, past experience, and knowledge of yeast biology will help to create tastier and more robust wines.

The recent influx of scientists into vineyards poses a challenge to the old-world institution of winemaking. Each year, winemakers embark upon the quest to create the perfect bottle of wine. Some rely entirely on empirical knowledge, while others are turning more toward scientific applications to help reach their goal. The trick is to use both methods without leaning too far in one direction or the other. Indeed, every person has a different concept of what the perfect wine tastes like, and a method that is deemed scientifically sound may not always apply when considering such empirical subjects as lasting flavor, aftertaste, and aroma.

West stresses that there are times when people must have faith in what they taste, rather than what they observe on a piece of paper. "There is a science and an art to winemaking," says West. "The people that are successful are the ones who can use both."