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5 Questions for Gavin Sacks

FACULTY FOCUS
By Amanda Garris

Gavin Sacks

 

Assistant professor Gavin Sacks joined the department of Food Science in January of 2007. Trained as an analytical chemist on problems in nutrition and geochemistry before working with wine, he currently teaches courses on wine and grape flavor chemistry and has an active research program focused on wine chemistry.


How did you come to work with grapes?
As a Ph.D. student, I developed new software and instrumentation for analytical chemistry applications. I enjoyed the work, but wanted to pursue a position that would give me the opportunity to see a direct impact of my research on individuals. I developed an interest in wine soon after I arrived at Cornell for graduate school, and after finishing my degree in 2004 I had the opportunity to work at Shalestone Vineyards on Seneca Lake with owner and winemaker Rob Thomas. When I saw that Cornell was advertising a faculty position for a wine chemist, I realized that working on wine and grape chemistry, and more generally on flavor chemistry, would provide an opportunity for me to work directly with the end users of my research – winemakers and students.

What are the major challenges for you?

One challenge is that flavor chemistry research rarely yields "fixed guidelines" for all situations, although that's often what the industry would like. My goal is not to tell people how to make wines or grow grapes, but rather to help winemakers and growers understand how their decisions are likely to affect eventual wine flavor—and to provide analytical tools that will help them make these decisions.

Another major challenge of all flavor research is that eventually you need to utilize a noisy, expensive, slow, and fickle detector: humans. We are still not able to predict with confidence how a person will perceive a mixture of flavor compounds like those found in wine, since one compound may mask another. On top of this, humans differ in their ability to perceive or describe odor-active chemicals, so a large panel of human sensory evaluators is necessary. Even if one can show differences in chemistry, eventually sensory analysis needs to be done to validate the chemistry results. It's often the research bottleneck.

Finally, we still aren't able to perfectly predict wine chemistry from grape chemistry. Most of the volatile aroma compounds in wines are produced from precursors during fermentation. Many are poorly extracted, and the link between the grapes and resulting wines is not always straightforward. So, instead of just evaluating grapes, we still need to do a relatively slow and expensive technique –winemaking—prior to doing analyses in many cases.

What is the most important thing students learn in your class?

Ideally, I want students to leave my class with the desire to ask "How do you know that?" The wine literature is filled with poorly supported hunches and anecdotal claims. Often, the underlying observation may be correct, but the explanation is not feasible. Picture a new winemaker being courted by a cork supplier who is pushing a new type of cork. What should the winemaker be asking? What information is needed to evaluate claims? How could they further test them? This is a general skill set needed in a range of professions, not just winemaking, but it's something that Cornell is particularly good at instilling in students.

What project would you pursue, if funding was unlimited?

I'm very interested in techniques that would allow us to evaluate grape chemistry on whole, intact grapes. From a research perspective, it means that we could get information on variation among grapes with minimal energy spent on sample preparation, and from an industry perspective it could provide us with a better tool to rapidly evaluate grape maturity. There are some existing commercial solutions that rely on reflected light and fluorescence, but other analytical approaches on the horizon could provide even more information.

 I'm also very interested in better understanding "aftertaste" and in vivo transformations of wine and grape flavor compounds in the mouth and nose. Most wine flavor chemistry work has focused on the chemistry of the original wine, but there are a few tantalizing studies that show that our mouths and noses act like bioreactors, modifying the compounds we put into them and their resulting flavor. Understanding this could go a long way towards explaining differences in perception among individuals or in understanding interactions between wines and foods.

What is your favorite part of your job?

By far, the best part of my job is when an undergraduate or a graduate student finds a job or internship that excites them. It means we didn't mess them up too badly.