Winemaking 101

The Birth of a Wine

    This time of year, grapes in California are getting ripe, and it’s time to think about harvesting them and turning them into wine. So you can better understand how that glass of Cabernet or Zinfandel gets to your table, here’s a description of the initial steps we vintners will be taking—on the way from vineyard to barrel and bottle—this summer and fall. The first thing we need to determine is the appropriate time to pick the fruit: If we pick too soon, the grapes have minimal flavor and color (for reds) and taste very acidic; if we pick too late, the sugars will be too high to finish fermentation, and we risk getting the taste of raisins or prunes in the finished product.
    Thus we need to be out in the vineyard every week as harvest approaches, taking samples and tasting the grapes. We measure things like sugar content and acid and pH levels, along with bunch weights, berry sizes and berry counts per cluster. There are no set numbers that mean the grape is perfectly ripe, so we have to correlate all this information with other qualities—flavors, skin turgidity and seed browning—before we can make the call.
    Once we know the fruit is ready, we generally get it picked within a day or two. In some years, however, like 2004, all the grapes in California got ripe at the same time, and there were not enough pickers to go around (which started to make mechanical harvesters look pretty good). Soon after that, there weren’t enough fermenters available to handle the uncommonly large loads, so some grapes stayed on the vines a few extra weeks and got overripe. As that can lead to “stuck” fermentations; the only way to correct it is to bring in the “Jesus factor,” and turn water into wine. This means adding a small amount of water, generally two days after crushing the grapes, before fermentation starts. Adding water, or “watering back,” is regulated by state law and is allowed for the purpose of helping the wine finish fermentation. The French think this is a sacrilege, but on the other hand, they are allowed to add sugar to their wine, and we are not.
    Once the grapes are picked in the cool morning air (or sometimes at night) and quickly transported to the winery, the crush process begins. The grapes are sorted through to pull out green or moldy ones as well as rocks, beer cans and the occasional grape knife. They are then fed into a machine known as a de-stemmer crusher, although some winemakers pull out the rollers so as to only de-stem the fruit, especially for delicate reds like Pinot Noir.
    The fruit is then either dropped or pumped into an open- or closed-top vessel (holding anywhere from 200 to 25,000 gallons). Then, especially in smaller, premium wineries, we cool the wine to about 45 degrees for a few days, and then warm it up to about 68 degrees and add yeast. There are hundreds of strains of wine yeast; each one has a slightly different effect on the bouquet and flavor, generating in a white wine, for example, everything from Fuji apple to pineapple-guava to lemon-lime characteristics. Most winemakers stick to their favorite three or four, and others let the natural yeast on the grapes do the job. Some like to add whole clusters of grapes or stems back into the fermenters to achieve different flavors.
    Almost all red grapes have white pulp, and it’s our job to try to get as much of the good red stuff in the skins out during fermentation. As the skins float to the top, we need to push them back down into the fermenting juice or pump the juice over the skins. This is typically done two or three times a day and may go on for 10 to 14 days, until the wine is fairly dry (little sugar left). During this time the yeast are feasting on the sugar and producing alcohol and carbon dioxide, and the skins are giving up their color and flavors.
    When fermentation is mostly complete, we put the wine through a press that separates the skins and seeds from the young wine. (White wines are made by pressing the unfermented grape first and using only the juice to ferment; and rosé wines are pressed after only a short period—from a few hours to a few days—of skin contact.)
    That’s essentially the birth process. Our next job is to try to raise these babies to be the next doctors and lawyers and cowboys of the wine world.
—Kent Rosenblum

Please visit our Privacy Policy for information regarding how we use this information.