White wines color

Muller-Spath (1977) was the first to contest the need to sulfite white juice before alcoholic fermentation. His research clearly showed that adding pure oxygen to non-sulfited juice before clarification improves the stability of white wine color without producing oxidation-type flaws. This process, called hyperoxidation or hyperoxygenation, consists of oxidizing juice polyphenols to precipitate them during clarification and eliminate them during alcoholic fermentation. 

The effects of juice hyperoxygenation on the stability of white wine color are variable, due to the existence of several reactional mechanisms. 

Flavonoids (sensu largo, i.e., including flavanoids) are important components of grapes and essential to wine quality. They are responsible for the color and astringency of red wines as well as for the yellow hue of oxidized white wines, and are also involved in the development of... 

The best of the white wines of Champagne, being all of the first quality, hut differing a Tittle in color and etiervee-Oence. 

Fine white wines of excellent quality, lightish brown, in color, aroma most agreeable, and some of rather sweet taste,... 

Here is a coulometric procedure for analysis of total sulfite in white wine. Total sulfite means all species in Reaction (A) and the adduct in Reaction (B). We use white wine so that we can see the color of a starch-iodine end point. 

Color. Precise specification of color has become more important as many producers sell large volumes of specific wines to a national clientele. There is the additional problem of low color white wines (5). 

Chemical Analysis. It is suggested that a set procedure be established for running specific analyses according to a specific timetable. For example, a visual and taste inspection of all wines every two weeks (two months for wines in barrels), malic and lactic acid analyses at weekly intervals during the malo-lactic secondary fermentation, and S02 and color analyses of white wines at least every two weeks until the wine is bottled. Basic analyses to monitor are V.A., S02, alcohol, pH, and T.A. 

Dry white table wines differ from red table wines in characteristics other than color. They contain lower concentrations of the puckery and astringent tannins. They usually have a higher acid content which makes them somewhat lighter in body and fresher on the palate. Dry white wines also are usually simpler in their aroma in contrast to the complicated aroma and bouquet that can develop in a red table wine. While it is possible to make white table wines from red-skinned varieties, for the home winemaker this task is very difficult because it is almost impossible to remove all traces of the pigment-containing skins from the juice quickly enough to prevent some reddish or amber color from developing. 

Ortega, A. F., Lopez-Toledano, A., Mayen, M., Merida, J., and Medina, M. (2003). Changes in color and phenolic compounds during oxidative aging of sherry white wines. /. Food Sci. 68, 2461-2468. 

A statistical breakdown of table wine by color categories was reported for the first time in 1979 (6, 7) and covered shipments from 1974 to 1979. The trend towards white wine is shown clearly. In 1974, white wine shipments were38,600,000gallons and, in 1979, shipments had reached 114,200,000gallons. 

Rose table wines also may be produced by using a white table wine colored with a dark red table wine. Many enologists prefer this method, as the white table wine base may be fruitier and fresher with more fermentation bouquet. 

Casein is nearly insoluble and must be dissolved at pH 11. Potassium caseinate is water-soluble and is preferred for this reason. Sodium caseinate is usually not used because it increases the sodium content of wine. Casein is a positively charged protein that flocculates in acidic media such as wine. When added to wine, casein adsorbs and mechanically removes suspended materials as it settles. In general, casein is used to remove undesirable odors, to bleach color and to clarify white wines. It is sometimes used as a substitute for carbon in color modification of juice and white wine. Usage levels are typically 10-30 g/hL. 

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