The perfect pinot problem

AS GRAPE varieties go, pinot noir is famously finicky. Got right, the thin-skinned grapes can produce some of the world’s finest wines. Central to that is plucking the grapes from the vine at the right time. Winemakers typically depend upon testing the level of sugar to determine if their berries are ready, but that is not terribly accurate. As pinot noir grapes reach late stages of maturity, the rate at which they gain sugars slows down just as the rate at which they accumulate the aromatic compounds that can grant wine a good “nose” goes up. And in wine, the aroma is a fundamental part of its appeal. Varying rainfall, temperatures and soil conditions all affect the rate at which aromatic compounds enter grapes, making it difficult for wineries to know whether they should harvest their grapes a few days or weeks after the increase in sugar tails off.

Michael Qian and Fang Yuan of Oregon State University had a local interest in the problem. The prime crop of the vineyards in Oregon’s Willamette Valley is pinot noir. And Oregon’s cool climate, short growing season and periodic heavy rains make determining whether grapes are ready for harvest particularly challenging. Curious to see if they could monitor directly the presence of aromatic compounds, the biochemists set up an experiment.