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Art and science blend to make great wine
Friday, Jan. 22, 2010
By Brian Clark, College of Agricultural, Human and Natural Resource Sciences
Ross with a student. (Photo by Robert Hubner, WSU Photo Services)
When sipping a fine winemaker’s red in front of the fire, it’s easy to appreciate the art that went into that blend.
But anyone who has tried to make wine finds him or herself quickly caught up in what amounts to a science project.
“Winemaking is certainly creative,” said Carolyn Ross, assistant professor of food science at WSU and an expert in the sensory analysis of wine. “But at its core, winemaking is a scientific endeavor. What folks often forget is that those two things are not incompatible.”
A fine sense
Take the fine art of fining, for example. Fining agents are substances added at or near the end of the winemaking process to improve clarity and adjust flavor, aroma and stability. In other words, fining tweaks a wine’s sensory qualities.
And the sensory quality is, of course, what enjoying a great wine is all about: the mouth feel, unfolding bouquet, color, acids, tannins and other aspects that wine writers deploy armies of adjectives trying to describe.
Ross takes a scientific approach to those adjectives by quantifying their chemical properties and training panels of wine tasters to communicate their importance.
“Fining is critical for consumer acceptance of white wines, as a haze or sediment in the bottle may eventually lead to consumer rejection and economic loss to the winery," Ross and her colleagues wrote in a recently published article in the American Journal of Enology and Viticulture. "Together with racking and filtration, fining agents improve clarity, define aromas and increase shelf life.”
But, the researchers added, fining also may adversely impact the sensory quality of wines. The effect depends upon a complex relationship between the fining compound and the type of wine being fined.
“Fining is definitely where some basic scientific practice is essential to making a good wine,” said Ross.
She and her team fined chardonnay and gewürztraminer made by a well-known Washington winery, which donated the wine to Ross’s team specifically for this series of experiments.
“There’s hasn’t been a lot of research done on the fining of Washington wines,” Ross said. Because wine is so chemically complex, it is very “place-specific:” grapes of the same variety grown in different areas produce wines with varying sensory qualities; so research, too, needs to be place-specific.
Ross and colleagues tested a wide variety of fining compounds, both those in demand by the industry (bentonite (clay), isinglass (protein), Sparkalloid (polysaccharide and diatomaceous earth) and activated carbon) as well as less researched agents (wheat gluten and whole milk).
The team’s paper makes for fascinating reading, as it backs up subjective-seeming words like “fruity” with scientifically quantifiable information: “Isinglass is said to enhance fruity aromas in wines,” the researchers wrote. “In gewürztraminer, this was demonstrated in that the highest fruit aroma and flavor intensities were observed in the isinglass treatment.
"The opposite was observed in the chardonnay, where isinglass had the lowest fruit aroma and flavor intensities.”
Ross is quick to point out that results with fining will vary with the specific grapes and winemaking techniques being used in a particular batch of wine.
Small-batch testing advised
“What winemakers should do,” she said, “is bench-test small amounts of wine to see the concentration of fining agent that works best. Take small amounts of wine and use different but controlled doses of fining agents. It’s a good idea to jot down what is used in a notebook, so the winemaker can compare results over time.
“Complicated scientific equipment is not necessary," she said. "Visual evaluation of the action of a fining agent should be enough to tell a winemaker which way to go.
"In three days to two weeks, depending on the fining agent, you’ll be able to see how much settling has occurred. And what you’re going for is the point where there is no more sediment accumulating and you’re seeing the maximum clarity in the wine.”
The take-away lesson here is that careful observation aids creativity. Like the poet’s or the novelist’s, the winemaker's muse is aided by a keen eye for detail.