Students explore delicate balance of wine chemistry

July 07, 2011

Three Chemistry students are learning that there’s more to producing fine wine than stomping grapes and corking bottles.

Already deeply involved in their summer student-faculty research project, George Williams, Eric Liggins and Kyle Hunter are beginning to understand the precision testing that means the difference between a rich bodied Cabernet Sauvignon and something just short of kitchen vinegar.

Kyle Hunter, Eric Liggins, Professor Steve Robertson, and George Williams.

“Today, tomorrow…yesterday, it’s literally that critical,” says Williams, a senior Biochemistry major from Glen Burnie, Md., now in his second year of studying the fine points of viticulture. “You have to know when to harvest, when to stop the fermentation process by frequently testing the grapes and wine frequently for values that determine the flavor.”

The team’s ultimate goal is to develop a program at McDaniel that allows local vintners to send in their wine samples and receive results inexpensively in one to three days, according to Liggins, a junior from Woodlawn, Md., who’s planning to apply his Biochemistry major to pharmacy school. Existing commercial testing programs range from $15 to $100 per sample and take as long as a month to get results.

The students are perfecting their gas chromatography and nuclear magnetic resonance (NMR) techniques to create a standard and begin testing for acidity, sulfites, ethanol and other variables that influence the quality of the wine. They will test wine from local vintners as well as fermenting their own two crocks of wine prepared from juice concentrated in New Zealand. Local orthodontist and winemaker who also is a McDaniel alumnus, Bob Scott gave the wine researchers a funding gift to purchase testing equipment.

Hunter, a sophomore Chemistry major and the junior member of the team, is learning his way around wine chemistry. He keeps the group’s work statistically valid. Since Hunter is minoring in Forensic Science, he’s not planning to make a career in the vineyards.

Sophomore Kyle Hunter with Professor Steve Robertson.

Under the mentoring of McDaniel lab instructor Steve Robertson, the team now talks comfortably about brix or sugar content, the hazards of too much sulfite, stopping fermentation with potassium sorbate, the dreaded mildew-y smell/taste that comes from trichloroanisole or TCA and the fine details of exactly when to harvest different varieties of grapes.

Robertson, who taught chemistry at Seneca Valley High School for 30 years and came to McDaniel to coach track, has long been interested in wine chemistry.

“There’s a beauty to grape growing, to producing wine that is a result of the interaction of leaf, sun and soil,” he says, explaining that wine production has an agricultural relationship with science. Robertson found an eager student in Williams and the two of them spent the summer of 2010 introducing themselves to wine chemistry.

Williams plans to continue with the research, turning his interest in the chemistry of viticulture into a capstone project or ambitiously two projects during his senior year. The first involves detecting the flavonoids in the grapes to predict exactly when they should be harvested. Traditionally vintners look at acidity, sugar content and other values to decide when to pick the grapes, but Williams will work with Scott’s grape cultivars at his Bellendene Vineyard to predict optimum harvest time based on the flavonoid anthocyanin.

Senior George Williams.

If time allows, Williams would also like to tackle the complex TCA problem to try to determine where the odor and taste that resembles wet newspapers comes from. There seems to be some question about whether the chemical causing cork taint really comes solely from corks or there are other influences such as whether the juice is fermented in oak barrels or not.

Detectable by humans at minute levels – one part per billion or a drop in an Olympic-size swimming pool – TCA costs the wine industry about $1 billion a year and affects 3-5 percent of corked wine, Robertson says. Williams is interested in using NMR (Nuclear Magnetic Resonance) technology to develop a less expensive TCA detection alternative as compared to the typical commercial cost of $120 per sample.

For now, the chemists are concentrating on their own vintage fermenting in their Eaton Hall lab.

Junior Eric Liggins.