Information on the making of wine.

Wine is the term used for fermented alcoholic beverages made from any fruit or fruit juice. However, in practice, almost all wine is made from grapes, as they contain the most sugar of any fruit. Within the grape family, the species native to Europe is known for producing the best wine, aptly named vitis vinifera. Varieties of this wine grape species are often named on wine labels, like Chardonnay, Merlot or Shiraz.

While wine is usually made as close to the vineyard as possible, as a means to ensure the best fruit quality, home winemaking is growing in popularity as a hobby. Many home-winemakers choose to start with fresh fruit or juice, in some cases growing it themselves, while others prefer to use packaged kits or concentrates. Advances in recent decades in our understanding of the fermentation process, in the range of supplies available for home use and in communication through resources like the internet have made it easier to make better quality wine at home than ever before.

All beverage alcohol is produced through fermentation, a natural process by which yeasts convert sugar into alcohol. Fermentation is a form of spoilage, but one which winemakers can control to achieve desirable results. Yeasts are the active agents, microscopic organisms of the fungus kingdom. They occur naturally in the environment, clinging to the waxy ‘bloom’ on the skins of fresh fruit. However, most winemakers choose to inoculate with cultured strains of yeast for more control over the outcome.

Yeasts consume sugar as fuel and break it down into alcohol and carbon dioxide. Much energy is released in the process, generating heat and allowing the yeasts to grow and reproduce. The recipe for alcoholic fermentation is:

Both the complex chemical reactions of fermentation and the heat it produces will change the taste of the raw material. Flavors and aromas not found in fresh grapes frequently emerge in wine, released or created through fermentation. The heat generated can also alter flavor, much like simmering a soup or a stew deepens and softens the flavor of its raw ingredients.

White wines are made by fermenting only the clear juice of grapes, while red wines acquire their intense color and distinctive flavors by fermenting whole crushed dark-skinned grapes. In general, white wines benefit from long, slow cool fermentations, while extra heat is needed to extract color from the grape skins for making red wine. Since carbon dioxide is a natural by-product of fermentation, sparkling wines can be made by fermenting wine in a closed vessel under carefully controlled conditions.

Contributed by: Marnie Old
Marnie Old is the Philadelphia area’s leading wine educator and highest profile sommelier. At 34, she is one of the youngest women to be sought after, both nationally and internationally, as a speaker on wine and beer. She is a member of the wine faculty at the French Culinary Institute in Manhattan and the regional wine educator for Wine & Spirits Magazine. Marnie writes beverage columns for Philadelphia Magazine and Pennsylvania’s Wine & Spirits Quarterly and is a contributing editor for Santé Magazine. She is the only wine professional in the region enrolled in the Master Sommelier program.