production goes to make wine; of the rest, about two-thirds are eaten fresh and a third are made into raisins There are many thousands of grape varieties Most wine varieties originated in Europe, while varieties for eating fresh or making into raisins can often be traced back to western Asian parents Wine grapes come in relatively small clusters and are acidic enough to help control the yeast fermentation; table grapes come in large clusters and are less tart; raisin varieties have a thin skin, high sugar content, and loose cluster structure to facilitate drying The commonest table and raisin grape in the United States, the Thompson seedless or sultana, is a variant of an ancient Middle Eastern all-purpose variety, the Kishmish Table grapes are quite diverse They may be seedy or seedless, deep purple with anthocyanins or pale yellow; their sugar content may range from 14 to 25%, their acidity from 0.4 to 1.2% They may have a fairly neutral, green aroma (Thompson seedless), or be flowery and citrusy from terpenes (muscat), or musky with anthranilate and other esters (Concord and other American varieties) Most commercial varieties today have been bred to be seedless, crisp, tart, and sweet, with a long storage life Thompson seedless grapes picked in the cool of the morning and treated with antimicrobial sulfur dioxide can be held for as long as two months at 32ºF/0ºC Raisins Grapes are easily preserved by sundrying to make raisins In the United States this is usually done by laying the grapes on paper between rows in the vineyard for about three weeks Raisins are naturally brown and have caramel flavor notes due to a combination of browning-enzyme oxidation of phenolic compounds and direct browning reactions between sugars and amino acids (pp 269, 778) Both of these processes are ...fairly neutral, green aroma (Thompson seedless), or be flowery and citrusy from terpenes (muscat), or musky with anthranilate and other esters (Concord and other American varieties) Most commercial... brown and have caramel flavor notes due to a combination of browning-enzyme oxidation of phenolic compounds and direct browning reactions between sugars and amino acids (pp 269, 778) Both of these processes are ... have been bred to be seedless, crisp, tart, and sweet, with a long storage life Thompson seedless grapes picked in the cool of the morning and treated with antimicrobial sulfur dioxide can be held for as long as two months at 32ºF/0ºC