Deciphering Harvest-Time Decisions

by Kent Rosenblum



HARVEST IS A TIME WHEN THE GRAPE can be a winemaker's best friend-or worst enemy. Picking ripe grapes at the peak of perfection is the ideal way to start making a wine of distinction, but it's much more complicated than that. There are some 300 different decisions that need to be made during harvest and throughout the life of the wine, each decision with the potential to send the wine in a different direction.
Many of the earliest decisions happen in the vineyard up to a year and a half before the harvest. Pruning in the early winter sets the stage for the crop level. Typically, vines that are carrying too many grapes make weak, thin wines, so balancing the crop is very important. (This is why many of the old vineyards produce great fruit year in and year out-their crop levels are low and balanced, say one to three tons per acre, whereas vines in the Central Valley can crop as high as 12 tons per acre.) There are also many preharvest decisions to be made related to the use of water, minerals and nitrogen, as well as sprays like sulfur, herbicides and mildewcides.
When choosing the proper time to harvest grapes, the winemaker generally looks at several scientific parameters. Brix, or percent of sugar, is important. Usually a brix above 23 or 24 percent indicates ripe fruit; however, the pH and total acid need to be in sync to make a good wine. These days, most winemakers will be out in the vineyard tasting the fruit, making harvesting decisions based on flavors and numbers. Lately, the trend has been to let the grapes get slightly overripe to insure rich flavors and fruit-driven bouquets with soft tannins. Other factors the winemaker considers are the time and temperature of the grapes at harvest (i.e., white grapes and light reds like Pinot Noir are better harvested cool), whether the grapes are harvested manually or by machine (with manual picking you get the stems; using machines you only get the berries) and the size of the transportation vessel (they range from a 40-pound lug to a 10-ton gondola).
Once the grapes are at the winery, there are many immediate decisions to be made. One is the size and type of tank the grapes will go in. Another is whether to sort the fruit or not. The winemaker also needs to decide the level of sulfur dioxide, or SO2, and other additions such as acid, tannin, vitamins and nitrogen, and chose between cultured or natural yeast, before selecting the length and temperature of fermentation (cool fermentations enhance fruit, and warmer ones emphasize phenolics and extract).
The wine is then pressed, separating it from the skins and seeds (with white wine, this is done before fermentation). The time and intensity of the pressing can affect the flavors and tannin levels. The winemaker must then decide whether to induce a secondary fermentation, called malolactic. Generally, good red wine goes through malolactic using specific bacteria that changes malic acid to lactic acid, creating a softer mouth feel.
Now it's time to put the wine to bed for a while and let it mature. Most fine wine is aged in 60-gallon oak barrels from forests in France and America, which impacts the final product in the same way as the winemaker's spice rack. Eventually, we winemakers will need to consider filtering, bottling, packaging and sales strategy, but suffice it to say that once the rush of harvest is over, we can take a deep breath and evaluate what we've created.