volume calculated as potassium sulphate. Calcium carbonate in such quantity that the content of tartaric acid in the finished wine shall not be less than 0.15 percent weight by volume. Also, sulphurous acid, including salts thereof, in such quantity that its content in the finished wine shall not exceed 70 parts per million in the free state, or 350 parts per million in the combined state, calculated as sulphur dioxide. Caramel, amylase and pectinase at a maximum level of use consistent with good manufacturing practice. Brandy, fruit spirit or alcohol derived from the alcoholic fermentation of a food source distilled to not less than 94 percent alcohol by volume. Prior to final filtration may be treated with a strongly acid cation exchange resin in the sodium ion form, or a weakly basic anion exchange resin in the hydroxyl ion form. Vintages In the United States, for a wine to be vintage-dated and labeled with a country of origin or American Viticultural Area (AVA; e.g., Sonoma Valley), 95% of its volume must be from grapes harvested in that year. If a wine is not labeled with a country of origin or AVA the percentage requirement is lowered to 85%. Vintage wines are generally bottled in a single batch so that each bottle will have a similar taste. Climate's impact on the character of a wine can be significant enough to cause different vintages from the same vineyard to vary dramatically in flavor and quality. Thus, vintage wines are produced to be individually characteristic of the particular vintage and to serve as the flagship wines of the producer. Superior vintages from reputable producers and regions will often command much higher prices than their average ones. Some vintage wines (e.g. Brunello), are only made in better-than-average years. For consistency, non-vintage wines can be blended from more than one vintage, which helps wine-makers sustain a reliable market image and maintain sales even in bad years. One recent study suggests that for the average wine drinker, the vintage year may not be as significant for perceived quality as had been thought, although wine connoisseurs continue to place great importance on it. Tasting Wine tasting is the sensory examination and evaluation of wine. Wines contain many chemical compounds similar or identical to those in fruits, vegetables, and spices. The sweetness of wine is determined by the amount of residual sugar in the wine after fermentation, relative