Winemaking: A Simple Explanation of a Complex Process.


One of the most beloved episodes of the classic sitcom “I Love Lucy” features Lucy and Ethel visiting a winery where they are recruited to stomp grapes — and hilarity ensues. These days, few (if any) wineries actually use human foot power to press the grapes for their wines, and instead rely on high-tech machines that gently extract the juice from the grapes while still maintaining the delicate skins. The shift away from rambunctious barefoot grape-stomping is just one of the many changes to the process of winemaking over the years. Today’s winemakers are combination farmers, scientists and gamblers as they devote their lives to creating the best-tasting, most technically perfect vintages they can.

However, there are basic winemaking steps that all vintners follow. While some specifics can vary, such as the amount of yeast added or the type of barrels used, the general process is the same. This ensures that whatever type of wine you buy, no matter which winery it comes from, you have a general idea of what to expect.

The Growing Process

All wine starts in the vineyards, where growers work throughout the year to grow the perfect wine grapes. The most common wine grapes come from the vitis vinifera family, a European type of grapes that includes the merlot, chardonnay, zinfandel and cabernet sauvignon varieties. However, certain vineyards also raise other types of grapes; you might find a winery largely focused on v. vinifera grapes with a few fields of specialty grapes, such as riesling.

Ideally, grapes need a long growing season, with warm days and cooler nights. The weather is a major factor in viticulture; a season that is especially hot and dry or particularly wet can significantly impact the quality of the grapes, thus impacting the taste and color of the winery’s products from year to year. However, most growers work hard to maintain consistency, while also experimenting with new methods of growing grapes to improve their products.

White Wine Production

Once the grapes are ready for harvest, usually in early autumn, production begins. The first step to producing any type of wine is to clean and prepare the grapes and the machinery. That means removing stems and field debris — especially insects — and cleaning and sterilizing the machinery, as even a small contaminant can ruin an entire batch of wine.

White wines are arguably easier to make than red wines. Once picked and cleaned, the grapes are crushed in a wine press for about two hours, and the juices extracted into chilled holding tanks. While in the holding tanks, sediments fall to the bottom and are then removed, leaving behind clear juice that’s transferred to fermenting tanks. Once in the fermenting tanks, the winemaker adds yeast to help convert the sugars in the juice to ethanol, and ensures that the tanks are free of any air. Air in the fermenting tanks can encourage the growth of bacteria, which can spoil the wine in a matter of hours.

Once the yeast has been added, white wine ferments anywhere from 10 to 30 days, depending on the winemaker’s preference. In the case of wines fermented in oak barrels, such as chardonnay, the winemaker may perform another fermentation process, in which malic acid is turned into lactic acid, creating a less acidic and creamier wine. In any case, white wine doesn’t generally need to age very long; when you buy white wine, you should plan to drink it soon after purchase.

Red Wine Production

The production of red wine starts in much the same way, with the grapes being crushed. However, that’s where the similarities end. Red wine grapes are crushed into a pulp, which is allowed to cold soak for several days to develop richer colors and flavors. Once the soaking process is complete, the winemaker adds yeast to begin the fermentation process. As the wine ferments, the skins rise to the top of the tank and form a “cap,” which must stay in contact with the liquid as much as possible to give the wine tannins and color. The fermentation process takes between 10 and 14 days, after which the wine is pressed away from the skins and placed into barrels for aging.

While most white wines are not aged for very long, red wines usually age in the barrel for several months, and in some cases, up to 40 years. However, because the aging process can change the flavor of the wine considerably, not all wines are meant to be aged and are bottled for drinking almost immediately after fermentation. When you buy red wine, you can store it for several years without it spoiling.

Winemaking is a complex process that has evolved over hundreds of years, and continues to evolve thanks to new technologies and increasing understanding of the science behind growing grapes and producing wine — although there is still hilarity to be found in the idea of stomping on grapes.

About the Author: Wine lover Mary Michaelson spends most of her weekends exploring the vineyards and wineries of the Napa and Sonoma regions that are close to her home in San Francisco. She tried making her own wine once, but the disastrous results led her to stick to writing about wine and leave the production to the professionals.

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