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At iWinemaker, we continually strive for accuracy and completeness. Please contact us if you have any comments or suggestions regarding the definitions below.
Acid Blend A mixture of tartaric, malic and citric acids, acid blend is patterned after the combination of acids that occur naturally in grapes and is a convenient way to increase acidity while maintaining grape character. Although the combination varies by provider, acid blend tends to be either 50-25-25 or 40-40-20 tartaric-malic-citric. Due to its malic acid component, acid blend typically should not be added to a wine after malolactic fermentation is complete.
Appellation From the French, a geographic designation for a grape growing region. An appellation can be quite large on the order of a State or Province or quite small on the order of a valley or even a particular chateau. Appellations are typically approved by governmental agencies who also regulate the manner in which an appellation name can be used for a particular wine blend. As an example for a wine to carry the Napa Valley appellation name on its label, 85% of that wine must come from grapes grown within the Napa Valley appellation.
Bentonite An aluminum-silicate clay originally found around Fort Benton, Wyoming, Bentonite is commonly used to fine white wines and, to a lesser degree, red wines. The negative charge associated with Bentonite attracts a variety of suspended solids in wine causing them to precipitate which typically results in a more clear and stable wine with reduced off odors and flavors. Prior to addition, Bentonite should be hydrated with a small amount of warm water. The wine should be racked off the finings within two weeks of addition.
BRIX A measurement of sugar in water-based solutions such as grape juice. One degree BRIX is equal to one percent sugar in the solution. Sugar content in juice is typically measured by a hydrometer or refractometer. The BRIX and Balling scales are essentially the same.
Calcium Carbonate The main component in chalk, food grade calcium carbonate can be used to decrease acid (primarily tartaric acid) in wines. Due to the undesirable flavor calcium carbonate imparts to wine in large amounts, it typically should not be used to decrease acidity by more than four tenths of a percent (4g/ml). Many winemakers prefer blending a high acid wine with a lower acid wine to decrease acidity rather than resort to the addition of chalk.
Campden Tablets Consisting of either Potassium Metabisulfite or Sodium Metabisulfite, Campden tablets are a convenient way to accurately measure sulfite additions to wine. The tablets should, however, be crushed before they are added making them often less convenient than sulfites in powdered form.
Citric Acid The small amount of citric acid that occurs naturally in grapes is metabolized by yeasts during fermentation leaving little in finished wine. Citric acid is sometimes added to wines to reduce iron haze (an increasingly uncommon problem with modern winemaking equipment) or to impart a crisp, albeit artificial, flavor to white wines.
Diammonium Phosphate (DAP) Commonly used as a fertilizer, Diammonium Phosphate provides nitrogen that promotes yeast growth and aids in a more complete and trouble-free fermentation. Diammonium Phosphate is the main ingredient in most commercial yeast nutrient preparations.
Egg Whites Consisting of approximately twelve percent albumin and globulin, egg whites are a relatively gentle protein-based fining agent. Like gelatin, albumin and globulin attract suspended solids in wine including tannins. Egg whites are not suitable for fining white wines. Prior to addition, a pinch of salt and a small amount of water should be added to the egg whites which should then be whisked but not to the point of foaming. The wine should be racked off the finings within two weeks of addition.
Free Sulfites A naturally occurring substance in grapes, sulfites (sulfur dioxide, SO2) act as an anti-oxidant as well as an anti-bacterial and therefore reduce the risk of wine spoilage. Free sulfites refer to those sulfites that are not molecularly bound to other materials and therefore available to bind to oxygen and bacteria should they be introduced to the wine. In high dosages, sulfites have the taste and odor of burnt matches, in low doses, they are essentially undetectable. Approximately one in 10,000 people are allergic to sulfites.
Gelatin Powder A protein derived from the collagen found in the connective tissue of animals, gelatin powder is commonly used to fine red wines and, to a lesser degree, white wines. The positive charge associated with gelatin attracts suspended solids in wines including tannin and as such reduces astringency and bitterness. Prior to addition, gelatin should be hydrated with hot or boiling water. The wine should be racked off the finings within two weeks of addition. Gelatin is considered the most effective of protein-based fining agents; over addition will reduce the flavor and color of the wine to a noticeable degree.
Grams per Milliliter A unit of measure for the amount of acid (grams) in a quantity of wine, juice or must (milliliters) that is typically abbreviated g/ml. Grams per milliliters corresponds directly to tenths of a percent such that as an example, 7 g/ml is equal to 7 tenths of a percent or 0.007. For iWinemaker calculators, enter acid levels an integer plus up to one decimal place, for example 7.5.
Malic Acid Along with tartaric acid, malic acid is one of the two principal acids that occur naturally in grapes. Malic (from the Latin malus or apple) acid is found in a number of fruits other than grapes and provides wines with a provides a tart, fruity flavor. Malolactic acid converts malic acid to equal parts of lactic (from the Latin lact or milk) acid plus carbon dioxide. Malolactic fermentation therefore both reduces total amount of acid in a wine and changes the crisp malic taste to a more "buttery" lactic taste.
Milligrams per Liter A unit of measure for the amount of free sulfites (milligrams) in a quantity of wine, juice or must (liters) that is typically abbreviated mg/L. Milligrams per liter corresponds directly to parts per million (ppm) such that as an example 50 mg/L is equal to 50 ppm.
Must The mixture of unfermented juice and crushed grapes that results from crushing, and typically destemming, fresh grapes. For red wines, one typically ferments the must and then presses out the new wine. For white wines, one typically presses the must and then ferments only the juice.
Oak Chips Although they are not a complete substitute for barrel aging, oak chips provide much character associated with oak without the expense, complexity and labor of barrels. When oak chips are added to stainless steel, glass or food grade plastic storage, they impart the flavor of oak but not the microoxidation that is unique to barrels. Like barrels, oak chips are made from either French, Central European and American oak with light, medium and heavy toast.
Potassium Metabisulfite A white-yellow powder, Potassium Metabisulfite (K2S2O5) is a common means of adding sulfite to wine. Potassium Metabisulfite is 57% sulfur dioxide which, when not bound to other substances in wine, acts as a preservative. In high dosages, sulfites have the taste and odor of burnt matches, in low doses, they are essentially undetectable. Approximately one in 10,000 people are allergic to sulfites.
Sodium Metabisulfite A white-yellow powder, Sodium Metabisulfite (Na2S2O5) is a decreasingly common means of adding sulfite to wine. Sodium Metabisulfite is 57% sulfur dioxide which, when not bound to other substances in wine, acts as a preservative. Unlike Potassium Metabisulfite, Sodium Metabisulfite can add off-flavors to wine and is currently banned in the United States for use in commercial wines due to health concerns surrounding sodium. In high dosages, sulfites have the taste and odor of burnt matches, in low doses, they are essentially undetectable. Approximately one in 10,000 people are allergic to sulfites.
Tartaric Acid Along with malic acid, tartaric acid is one of the two principal acids that occur naturally in grapes. Tartaric acid is rarely found in fruits other than grapes, helping to provide grape wine with it's distinctive taste. Because tartaric acid is not effected by malolactic bacteria, it may be added after malolactic fermentation to increase acidity without concern for restarting this secondary fermentation. It is therefore commonly added to red wines and chardonnay to adjust acidity before bottling.
Titratable Acid The amount of acid in the juice, must or wine as measured by the process of titration. Wine titration kits determine the amount of acid through the addition of a reagent of a known concentration until a color change in the solution occurs. The quantity of reagent required to effect the color change determines the quantity of acid in the sample.
Varietal A designation for a wine made from a particular variety of grape. Although regulations vary by region, for a wine to be called a varietal, it typically must consist of wine made from at least 75% of that grape variety. Most wines produced outside of France carry a varietal designation when applicable. If no grape variety accounts for a percentage that would allow for a varietal designation, the wine is typically referred to as (Red or White) Table Wine. Examples of varietals include Cabernet Sauvignon, Chardonnay, Gewürztraminer, Merlot, Pinot Grigio and Riesling.
Vintage Refers to the year in which the grapes from which the wine were harvested. Although regulations vary by region, for a wine to carry a vintage designation, 95% of the blend must come from grapes harvested in a particular year. Vintage designations are particularly important for wines that come from temperate regions in which the quality of the wine is subject to significant yearly variance.
Yeast Hulls The remnants of expired yeasts, yeast hulls or yeast ghosts provide live yeasts with nutrients that promote a more complete and trouble-free fermentation. Yeast hulls are an ingredient in most commercial yeast nutrient preparations.
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