Wine

The taste of a wine is a reflection of where its grapes were grown. The soil gives the wine its flavour, which is why wines produced in certain areas have a distinctive flavour.

Clarification Once fermentation is completed, the clarification process begins. Winemakers have the option of racking or siphoning their wines from one tank or barrel to the next in the hope of leaving the precipitates and solids called pomace in the bottom of the fermenting tank. Filtering and fining may also be done at this stage. Filtration can be done with everything from a course filter that catches only large solids to a sterile filter pad that strips wine of all life. Fining occurs when substances are added to a wine to clarify them. Often, winemakers will add egg whites, clay, or other compounds to wine that will help precipitate dead yeast cells and other solids out of a wine. These substances adhere to the unwanted solids and force them to the bottom of the tank. The clarified wine is then racked into another vessel, where it is ready for bottling or further aging.

Some clarifiers are animal-based products, while others are earth-based. Common animal-based agents include egg whites, milk, casein, gelatin, and isinglass. Gelatin is an animal protein derived from the skin and connective tissue of pigs and cows. Isinglass is prepared from the bladder of the sturgeon fish. Bentonite, a clay earth product, serves as a popular fining agent.

Egg whites from chicken eggs are used for red wine clarification and are removed before the wine is bottled. The egg whites are not specially processed or separately distributed for the wine industry. They are regular, store-bought eggs or farm eggs. Two or three egg whites can clarify a 55-gallon barrel of wine. Winemakers in France (Burgundy) commonly utilize egg whites in their production because they can use the whites of the eggs after the yolks have already been added to their foods. Egg whites generally clarify more expensive wines (above $15 a bottle) or French wines which are expected to age. The most popular substance used to remove the proteins of domestically produced white wines is bentonite. It is a silica clay which picks up the organic proteins left by the grapes. If left in the wine, these proteins would denature and form long molecular strands. This process would result in wine that is either hazy or has loose sediment floating in it. Therefore, bentonite acts as an agent to improve the cosmetic appearance of the wine for the consumer. Bentonite is used to fine most inexpensive wines. Two to three pounds of bentonite clarifies 1,000 gallons of wine. Several other fining agents exist. Sparkaloid, a diatomaceous earth, clarifies white and red wine. Italian wine may be fined with either eggs, milk, or blood. Although blood of large mammals may serve as a clarifier in some Old Mediterranean countries, its use is forbidden in wine from either the United States or France. Both the clarifying agents and the removed proteins coagulate on the bottom of the wine tank or barrel. They are then removed through either a settling process or a cellulose fiber filter. The ingredient list of a wine will not state the clarifier as an ingredient because it is removed from the final product. Calling or writing to a particular wine company may be the best way to discover which fining agent they use. Wine may also be filtered to remove impurities. A wine can be filtered and not clarified, or clarified and not filtered. A wine marked "unfiltered" has not passed through a filtering substance, such as a plastic micropore filter. "Unfined" wines have not had a clarifying agent passed through them. Even though a wine label may state it is unfined, this may not always be the case. According to one California winery, some companies may mark a bottle of wine "unfined" as a marketing technique because no one avidly scrutinizes the wine producers to verify these claims.

(Tannins are naturally occurring compounds that precipitate proteins from a solution.) By pressing the wine at an early stage of the winemaking process, the tannins can be removed without the additional proteins.

Isinglass is used to fine selected white wine. Germany, which initially introduced this method, is one of the main countries that still uses this technique

The most popular substance used to remove the proteins of domestically produced white wines is bentonite. It is a silica clay which picks up the organic proteins left by the grapes. If left in the wine, these proteins would denature and form long molecular strands. This process would result in wine that is either hazy or has loose sediment floating in it. Therefore, bentonite acts as an agent to improve the cosmetic appearance of the wine for the consumer. Bentonite is used to fine most inexpensive wines. Two to three pounds of bentonite clarifies 1,000 gallons of wine. Several other fining agents exist. Sparkaloid, a diatomaceous earth, clarifies white and red wine. Italian wine may be fined with either eggs, milk, or blood.

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