Viticulture and Enology

Summary

Viticulture and enology are fields involved in the cultivation of grapes and the process of winemaking. Specifically, viticulture is the science of growing and cultivating grapes, and enology is the study of wine and winemaking (viniculture refers to the science and process of growing grapes for winemaking). The international wine industry uses techniques developed in antiquity in conjunction with modern research and technology to maximize the quality and flavor of the finished product. Although many winemakers strive to maintain the traditions of their ancestors, others strive for innovation, creating blends of grapes and hybrid grape varieties with new flavors. The single botanical species used to make wine, Vitis vinifera (wine grape), has led to the cultivation of more than 15,000 wine varieties. In the twenty-first century, winemaking occurs on every continent except Antarctica. Worldwide, grape cultivation and winemaking are a multibillion-dollar industry, and many universities offer graduate-level courses in viticulture and enology.

Definition and Basic Principles

Viticulture is the science of growing and cultivating grapes and grape vines, which includes planting grape seeds, training and maintaining grape vines, and harvesting grapes to produce grape juice, wine, and other products. Enology is the study of wines and winemaking, which involves the fermentation of grapes and other methods used to create wine and impart specific flavors to the finished product. Viticulture and enology are the backbone of the wine industry, which also includes the commercial production, sale, and evaluation of wine products. Research in enology is used extensively in the culinary sciences, especially when learning to pair specific wines with certain foods and ingredients and in teaching wine appreciation to enthusiasts. In addition, enologists and viticulturists study the factors that contribute to wine flavor and the diseases that affect grapes and grape products.

Background and History

Viticulture and enology have been part of human culture for about eight thousand years since the first wines were made in the ancient Near East (modern Middle East). The Romans laid down the foundations for grape classification and the aging process of wine. They also pioneered using oak fermentation chambers (wooden wine barrels) and cork for bottling. (The earliest extant prose written in Latin is a survey on Roman viticulture.) Winemaking was nearly exclusive to Europe until the mid-nineteenth century when it spread to the Americas.

In 1863, Emperor Napoleon III of France asked chemist Louis Pasteur to investigate the factors that led to deteriorating wine quality. Pasteur's work was a landmark in understanding fermentation and led to the development of enology. The results of his research quickly spread around the world. In the 1880s, the University of Bordeaux in France and the University of California established the world's first institutions for the study of enology.

During the twentieth and early twenty-first centuries, most of the wine innovations came from the development of industrial winemaking procedures. Advancements in sanitation during this time also led to the cultivation of higher-quality, longer-lasting wines.

How It Works

The production of wine during a single year, called a vintage, involves three basic components—cultivation, processing and fermentation, and finishing.

Cultivation. Photosynthesis starts the process of converting carbon and chlorophyll to sugar, which is stored in the grapes. Each grape variety has a target ripeness level depending on the flavor desired. Viticulturists use tools such as spectrometers to measure the sugar level in the grapes and decide when to harvest them. Variations in environmental factors such as climate and soil quality affect the flavor of the grapes. The ideal condition for grape cultivation consists of warm, relatively dry days alternating with cool nights. Places where these conditions occur naturally, such as Northern California's Russian River Valley, produce the highest-quality wines. Deciding when to harvest is the next variable. Harvesting directly following rain may lead to watery grapes while harvesting following a dry spell leads to dry grapes with overly intense flavor. Although many industrial winemakers harvest grapes with combines that can pluck thousands of plants in a short time, the highest-quality wines are produced from hand-picked grapes.

Processing and Fermentation. After being harvested, the grapes are juiced. They are placed in a large container with a spout connecting to the bottom. When the container is filled to capacity, gravity will begin to crush the grapes, producing what is called free-run juice. The highest-quality wines are developed from this free-run product. Next, winemakers use air bladders or plungers to press the grapes. With each round of pressing, as liquid from stems, seeds, and skin is filtered into the juice, the quality of the juice declines.

To achieve fermentation, yeast is added to metabolize the sugars in the juice and create alcohol as a byproduct. Traditionally, the juice is placed into oak containers for fermentation, which impart a unique flavor. Modern wineries may also use stainless steel or polished concrete fermentation chambers, although most conduct some fermentation in traditional oak containers.

At this point in the process, all wine has a pale color. To make the wine red, the juice is soaked with grape skins. This imparts a red color to the juice, called cold soaking. This process may also increase the wine's complexity, aroma, and flavors. To prevent fermentation during cold soaking, the soaking chambers must be kept at cold temperatures—typically between 4 and 15 degrees Celsius (39 and 50 degrees Fahrenheit). To achieve this, some winemakers cold soak in underground chambers, and others use dry ice or industrial cooling units. After soaking, the temperature is raised to start fermentation.

Finishing the Wine. Once fermented, the wine is filtered to remove sediment and other materials. High-quality wine is filtered through a relatively loose filtration system, and some sediment is left with the wine so as to continue imparting flavor and characteristics. After filtration, wine may be bottled or transferred to oak storage vessels for aging. Many fine wines are stored in oak for periods ranging from a few months to a few years, allowing the flavor to change and develop. Even if the wine is immediately bottled, the wine must rest for several weeks or months within the bottle to achieve a palatable or desired flavor.

Applications and Products

Cultivars. The vast majority of wine is made from grapes that are varieties of a single species, Vitis vinifera, the noble or Eurasian grape. Although there are many other grape species, few make satisfactory wines. Most wines are made from varieties of V. vinifera, including Merlot, Cabernet Sauvignon, Pinot Noir, Syrah, Shiraz, and Sangiovese, which are among the most important varieties of grapes for red wine. Chardonnay, Pinot Gris, Riesling, and Sauvignon Blanc are among the most popular varieties for white wines.

Grape Liquors. In addition to wine, grapes can be used to produce a variety of other liquors. Champagne and sparkling wine are made either by injecting carbon dioxide into already-fermented wine or by adding more yeast and sugar to the wine to induce a second fermentation process. With the latter method, the wine is then capped in a special container that traps the carbon dioxide that is released as a byproduct of fermentation.

Brandy is another liquor produced by distilling grapes. To make brandy, the fermented juice is boiled until alcohol vapors rise from the liquid, at which point the vapors are captured and recondensed into a spirit. This process, called distillation, can also be used with other types of fermented fruits or vegetables to make spirits.

Fortified wines such as port and sherry have high alcohol content and are typically sweet. During fermentation, winemakers add distilled brandy to the wine. The alcohol kills the yeast in the wine and stops fermentation, thereby preserving more of the sugar in the grapes and simultaneously adding to the alcohol content.

Tartaric Acid. Tartaric acid is an organic crystalline acid found in grapes and several other fruits. During wine fermentation, deposits of tartaric acid collect in the fermentation vessels. Winemakers collect and sell tartaric acid as a food additive. It is used as a solidifying agent in cheese making and added to some foods to increase bitterness. Because of its antioxidant properties, tartaric acid has also become a popular additive for health food and drinks.

Pumice. Pumice is a mat made of grape leaves, skins, seeds, and stems that collect during the creation of red wine. Wine pumice is collected, dried, pressed into bricks, and sold to health and wellness companies for various products. Because pumice is high in vitamins, minerals, and antioxidants, it has become a popular food additive in various healthful beverages and supplements. Wine pumice has also become exceedingly popular in the cosmetic industry. In vinotherapy, winemaking residue is used to treat the skin. Pumice, for example, may be ground and used to create skin products and makeup. The French winery Château Smith Haut Lafitte is known for its line of beauty products created with its wine pumice.

Careers and Course Work

There are many roads to achieve careers in enology and viticulture. Enology involves knowledge of chemistry, microbiology, bacteriology, and botany. Viticulture involves extensive knowledge of horticulture, and experience in geology and climatology is also beneficial. There are many university programs available in horticulture and botany, and some schools offer courses in enology. Individuals with backgrounds in microbiology, botany, or agricultural studies may choose to focus on viticulture or enology during postgraduate studies. Some wine retailers and culinary education programs also offer classes in viticulture and enology.

Professional enologists may be employed by wine manufacturers or may conduct research for a university. The University of California, Davis, for example, provides training in viticulture and enology at the undergraduate and graduate levels and also employs researchers and research technicians. Funding for wine research can be obtained through a variety of organizations, private sources, and sometimes government and public granting agencies. Several medical agencies have also promoted enological studies, such as the medical benefits of wine and other grape products.

Social Context and Future Prospects

The impact of wine on culture differs widely between countries. In France, Italy, and much of Europe, wine is a staple of everyday life. Many Europeans are daily wine consumers. In the early twenty-first century, Italy overtook France as the world's largest winemaker. According to the International Organisation of Vine and Wine (OIV), Italy remained the top producer by volume a dozen years later, though their production volume remained close. France, Italy, and Spain, the world’s three largest wine producers, produce more than 50 percent of global wine production. In the United States and much of Asia, wine is more of a delicacy than a part of a daily routine. Though traditions differ, wine is collected and consumed in most countries.

A major debate in the wine industry in the early twenty-first century concerns the use of oak cork for bottling. Cork is a product made from the cork oak tree (Quercus suber). It has been used as a wine stopper for centuries because of its light and elastic nature—its compressibility allows it to form tight seals—and because it is largely impenetrable to gases and liquids. It is also sustainably harvested without pesticides from beneath the tree bark and allowed to regrow. A problem with cork, however, is that it can be the source of bacteria or fungi within the wine, allow leakage, or dry out and crumble when the stopper is removed. It is also more expensive than alternatives. Between the 1990s and 2009, the use of traditional natural corks declined by nearly one-third. Other closures gaining ground in the industry included metal screw caps, glass or plastic stoppers, and Diam corks, which consist of natural cork that has been ground, treated, and agglomerated into stoppers. In response to this trend, cork manufacturers turned to steam distillation and gas chromatography to prevent a malodorous fungal taint. By the late 2010s, natural corks were being used in about two-thirds to three-quarters of wine bottles, with screw caps sealing most of the remainder.

According to the OIV, extreme weather contributed to a decline in wine production in 2016 unprecedented since World War II. To adapt to changing temperatures and precipitation, earlier growing seasons, and species migration, wine-grape growers must improve their water conservation and capture, employ better irrigation and pest control, and invest in higher-tech, energy-efficient agricultural equipment. As climate change continues to alter typical weather patterns, winemakers must adjust their processes to a new climate. Additionally, consumers increasingly value companies that engage in earth-friendly practices. Upgrading equipment, avoiding harsh chemicals and pesticides, and using sustainable packaging will be increasingly important.

Modern trends include avoiding glass to store and ship wine. Wine sold in cans and boxes has gained popularity partly because these containers are easier to ship. Natural, non-alcoholic, and low-alcohol wines are also growing in popularity. The ancient wine-making practice of using clay amphoras has regained popularity in modern winemaking.

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