FOUNDATIONS OF WINE KNOWLEDGE 

By learning the basics of viticulture, winemaking, grape variety signatures, geography, climate and tasting you can confidently and effectively serve your guests and increase sales in support of your role.

VITICULTURE

Viticulture refers to the cultivation and harvesting of grapes. Understanding the basics of viticulture can help you understand the flavor profiles and characteristics of different wines. 

Sunlight

Sunlight plays a major role in the vine’s lifecycle. Required for photosynthesis, it provides both light and heat, which vary based on latitude and hillside exposure. 

Soil

Vinifera typically thrives in nutrient-deficient soils that stress the vine. Fertile soils encourage vigorous growth, numerous clusters, and, ultimately, diluted grape flavors. Deficient soils force the vine to send roots deep in search of water and nutrients. Heat retention and sun reflection can be important in cooler climates with shorter seasons, where a gradual, overnight warming effect is beneficial during cold off-hours. In a very hot and dry climate, however, water retention is a key factor, an asset to vines battered by the heat. 

Vine Cycle

The work done in the year leading up to harvest is what most influences vine and grape health at harvest. The growing season can be broken down into several phases: weeping, budbreak, bloom, fruit set, veraison, and harvest. This season runs from April through October in the Northern Hemisphere and October through April in the Southern Hemisphere, with dormancy in the remaining months.

Weeping

Weeping signals the beginning of a new growing season. As air temperatures surpass 50 degrees Fahrenheit, the vine’s roots, holding nutrients dormant over the winter, begin pushing energy into the upper parts of the vine, causing sap to weep from canes pruned in the winter.

Budbreak

A few weeks after weeping, a small node, or bud, of leaves will make the first push out of the cane. At this point, frost poses a major threat: if bud break occurs too early or there are late spring frosts, the vine’s ability to bear fruit for the year may be severely impacted. acids will happen from this point on.

Bloom & Fruit Set

Following budbreak, the bud grows into green foliage bearing embryos of very tiny, unopened flowers. Eventually, 6 to 13 weeks after bud break, flowers emerge in the bloom cycle, which lasts about 10 days. 

Veraison

Approximately 100 days after budbreak, grapes begin ripening as the vine transfers sugar from the leaves and shoot tips to the green, unripe clusters. Most of the increase in sugars and decrease in acid. 

Harvest

A harvest decision too early or too late can have a major impact on the outcome of the wine due to weather changes such as rain. Harvest in the Northern Hemisphere occurs between August and November.

Sugar level is one of many variables a winemaker or vineyard manager may use to determine the time of harvest. Roughly half of the sugar content translates into potential alcohol for the wine. In the US, the most common scale for measuring sugar content is Brix, the sugar content of a liquid solution in grams per 100 milliliters of water. Other scales exist including Öchsle. The range of Brix for grape harvest varies widely depending on the growing region and wine style. Sparkling wine producers may harvest in the high teens or low 20s to capture higher natural acidity, whereas harvest for dessert wines can exceed 30 degrees Brix.

Harvest Decisions

The actual decision of when to harvest is dictated by multiple factors, including Brix and/or pH levels; seed and stem lignification (hardening/ripening as carbohydrate reserves are built for the winter); the taste of the grapes, seeds, and stems; and the preferences of grape growers and winemakers. Growers also consider impending weather.

Harvest can be carried out mechanically or by hand. Though technology is decreasing the quality gap between the two, hand-harvesting is still considered the most quality-conscious approach—but comes with a larger price tag. Ideally, harvest happens very early in the morning or even in the middle of the night to ensure balanced acid, sugar, and temperature levels of the grapes. 

WINEMAKING
Winemaking is the process of turning grapes into wine. Different winemaking techniques can affect the flavor and quality of the wine. The major steps of winemaking are crushing, maceration, pressing, fermentation, aging, and fining/filtering, with many other processes and choices along the way. Some important terms to understand include:

Crushing

The area of a winery where grapes arrive is called the crush pad. As the name suggests, this is where the grapes are crushed, the first step in processing. White grapes typically enter the press upon arrival and are pressed immediately to extract juice. This limits the juice’s contact with grape skins, creating lighter, fresher wines. Red grapes may be either destemmed or put into fermentation tanks for whole-cluster pressing.

Maceration

Maceration, the contact of grape juice with skins before fermentation, may last a few hours up to a few days. It is typically carried out at temperatures too low for yeast to begin fermenting. This process encourages the extraction of more fruit and color from grape skins. 

Pressing

When grapes are pressed, they open and release the juice inside. Pressing must be done quickly enough to avoid overexposure to oxygen but gently enough to avoid breaking stems and seeds that contain bitter compounds. 

Fermentation

Most red and some white wines will also go through a second process called malolactic conversion (MLF or malo), either during or after the primary fermentation. Caused by a lactic acid bacteria, malolactic fermentation converts the tart, natural malic acid in grapes (present in green apples) to a softer, rounder lactic acid (present in dairy). 

Ripe grapes contain a lot of sugar, a required ingredient for alcoholic fermentation. Yeasts, which exist naturally on grapes, act on the sugars to convert them to ethyl alcohol. Commercial yeasts can provide greater consistency and specific attributes desired by winemakers. Wild yeasts, on the other hand, may add layers of complexity and flavor but are less reliable and sometimes produce unwanted flavors. To manage the fermentation process, winemakers often control temperature, limit oxygen exposure, and use sulfur dioxide (SO2).

Sparkling Wine

Sparkling wine contains a high level of carbon dioxide, which creates bubbles. Methods to produce sparkling wine include the traditional method, Charmat (tank) method, natural (ancestral) method, and carbonation method.

In the traditional method, championed in Champagne, a still base wine (vin clair) is bottled with liqueur de tirage, a sugar, wine, and yeast combination. This prompts a second alcoholic fermentation in the bottle, producing additional alcohol and CO2. The Charmat method is similar but usually occurs in large, pressurized tanks, and the wine is bottled quickly, without extended time on the lees.

Natural method sparkling wines will only have one fermentation that begins in the tank and finishes in the bottle. They are not disgorged by the producer. Lastly, carbonation is a cheap, industrial process in which CO2 is injected into a base wine; it is not typically used for quality winemaking.

Aging

Following fermentation, the aging, or élevage, of wines can dramatically impact flavor. Red wines are generally aged longer than white wines, which are typically bottled within a few months of harvest. Oak aging is more common for red wines. New oak (barrels that haven’t been used) will lend spice tones, complexity, and weight to the final wine. Neutral oak (barrels that have been used multiple times) offer oxygen exposure, but the barrel itself will impact the wine only minimally, if at all. Barrel type, size, and toast level, as well as the length of aging, will determine the oak’s final impact on the wine.

Fining

Another process for clarifying wines is fining, or collage, in which a fining agent such as egg white, bentonite (a type of clay), casein (a milk protein), gelatin (a protein derived from collagen), or isinglass (a material obtained from sturgeon bladders) is added to a wine to precipitate out solids. These additions can also aid in the racking process. 

Filtration

Before bottling, wine is usually filtered, passing through a membrane with microscopic holes that prevent any remaining solids, yeast, and bacteria from entering the bottle. Some argue that this process removes flavors from the wine. Certain styles, however, such as off-dry wines and wines that do not undergo malolactic fermentation, require filtration to prevent unintended bottle fermentation.

Sulfur

Sulfur dioxide is added at various points during the winemaking process, most often during fermentation and maturation, and before bottling. Sulfur has the preservative qualities needed to protect wine from oxygen. But too much SO2 may result in excess hydrogen sulfide, which leads to a rotten egg aroma. This can be so intense in a young wine that decanting is warranted. Avoiding sulfur usage entirely, however, which is common among natural wine proponents, can lead to premature spoilage.