Everybody knows that the best wine is made from ripe grapes.Or is it?
Different wine styles depend on a range of considerations. Chardonnay used for sparkling wine, for example, should have more acidity and less fruity character than chardonnay for a rich, oaky style; the fruit will be picked with different criteria in mind.
Making the decision of when to harvest is critical to the style and quality of the ensuing wine. An imaginary visit to the estates of three winemakers who do not share the same approach to harvest may prove enlightening.
First, let’s visit Mr. X. He is the most conventional vintner. As soon as the grapes turn color in early August, he goes out into the vineyard and starts testing the brix (percent of sugar) in the berries. Sugar- to alcohol yields during fermentation are about two to one, so 20-percent sugar will yield about 10-percent alcohol, the minimum for a stable wine.
For Mr. X, the brix is the be-all and end all. He needs to be able to say, “My merlot tested out at 23 brix today.”
The acidity isn’t that important to him (journalists rarely ask about it).
In the vineyard, he tests a few berries that are easy to pluck, which are also the most exposed, and thus the ripest, using a small refractometer. He doesn’t bother to test the back acres, figuring that they will all be about the same.
Mr. X doesn’t want to take too many risks in waiting to harvest. He’ll never be the first to pick, nor the last. Somewhere in the middle of the time that everyone is harvesting, he will look at his graphs, find a few berries that test out at a high sugar level and give the call to harvest.
When we visit winemaker Y, she is reading the latest microbiological studies. She likes to understand what goes on in wine at a molecular level, and she also likes to read ancient accounts of winemaking to see what has been done in the past with the benefit of experience instead of science.
When Ms. Y tests for sugar, instead of just testing one berry, she gathers a large random sampling from the entire vineyard, visually examining the vines for signs of senescence, when they change metabolism at the season’s end.
She tastes the fruit and checks the seeds to see if they are “dusky,” following the advice of the ancient Roman, Columella. Dusky seeds indicate physiological ripeness, even if the fruit isn’t perfectly ripe by technical standards.
Ms Y. wants the acids in her wine to be fresh and natural. The pH is also important to her because it indicates how much the berries’ acidity will be buffered by excess potassium that can unbalance the fruit, leaving the wine flat-tasting and unstable.
Ms Y. makes delicate wines; she may be the first to pick.
Our third winemaker, Mr. Z, wants to make aggressive wines with plenty of alcohol. He is the last to pick, counting on “hang time” to bring the fruit to its ultimate ripeness.
Mr. Z wants high sugars and big tannins. His attitude is that he, as winemaker, should use whatever tools are available to change the wine as he wishes.
Luckily his winery is well funded. He has a concentrator to deepen the wine, a reverse osmosis filter to refine it, and new oak barrels to age the wines. When no one is looking, he may add some raspberry extract to pump up the fruitiness and balance the wood.
Any of these three approaches to making harvesting decisions may result in fine wines, but the wines will differ.
Winemaker X will succeed best in a year that is sunny but cool, so that his fruit can accumulate the sugar he is looking for without losing too much acidity.
Winemaker Y will come out ahead in a hot, wet year when her fresh wines will outshine those from over-ripened, rot-tainted fruit.
When all goes well, winemaker Z will make white wines with “tropical fruit” flavors, and his reds will taste plummy; maybe even pruney.
In winemaking, luck and serendipity always play a large part, and a season which looks great may be a lost opportunity to the vintner who guesses wrong the best time to harvest. Greatness comes only to those who are willing to combine whatever scientific understanding they may have, or whatever standard industry practices they follow, with a personal vision of exactly what constitutes excellence.