GRAPES AND RAISINS
Grapes are sweet and sour fruits with a crunchy and jelly texture at the same time, covered by a thin skin that usually has a tiny whitish bloom on its surface. The inside of the grape contains seeds, unless you eat the seedless grapes. They exist in three general varieties - the table grapes are meant to be eaten, wine grapes are used for wine making, and raisin grapes are dried into raisins. The differences between these main groups of grapes is tartness/acidity and also the sugar content. Wine grapes for example are more tart than table grapes, making them more suitable for wine making as the acid controls the yeast fermentation process. Raisins are exceptional for their thin skin and high sugar content.
Looking at the total world production, about two-thirds of the grapes are made into wine, while most of the rest is eaten as is, and some of them are made into raisins. Grapes are available throughout the year (in Europe) and the American grapes are in season during the early autumn.
The woody vine of the genus Vitis is the plant that produces grapes. The most common one and the most present in Europe and Asia is the Vitis vinifera, from which both wine grapes and table grapes originate. In North America a number of native grape species also exists, including the Concord grape, stemming from the Vitis labrusca species. But there are many, many grape varieties, as any wine connaisseur knows, and they all have different colors, flavor, and develop different taste when "transformed" into wines.
When it comes to table grapes, they are either green or purple, and they are quite sweet and not as tart as the wine grapes. However, some of them are more unique than others in terms of flavor. For example, muscat grapes have some citrus flavor with a tint of flowers, while the seedless Thompson grapes are more mild and not very pronounced in any special flavor. They can also be stored for quite a long time in the cold if treated with anti-microbial agents.
Raisins are made simply by letting the raisin grapes dry in the sun for a few weeks. Their dark color is totally natural and their special flavor develops from chemical reactions that occur naturally within the grapes. The amount of dark color and the intense flavor can actually be controlled by temperature, and so the lighter raisins are simply made by drying in lower temperatures. For the golden raisins one has to add some additional "ingredient" in form of sulfur dioxide gas (it kills bacteria and mold).
What about the nutritional value of the grapes? They are rich in the antioxidative agents like vitamin C and manganese, and they also carry some metabolism-promoting B vitamins. Besides that, grapes are also famous for their high content of flavonoids (purple grapes) that reduce the bad cholesterol oxidation, which in turn reduces the risk of having a cardiovascular disorder. Flavonoids also reduce the risk of stroke and thrombosis. Grapes, and in particular the red wines, have been suggested as the food that protects the French from their bad habits of eating tons of butter, lard, and other non-healthy foods. It should be noticed however that wine consumption must be moderate in order to benefit your health: too much wine will instead lead to liver damage, high blood pressure, and possibly alcoholism and alcohol-induced accidents!
When buying grapes, select the firm, unwrinkled fruits, free of mold or excessive moisture in the package. It is alright for the grapes to have a whitish bloom - it is a protectant of the skin. Store your grapes in the refrigerator, otherwise they will spoil quickly in room temperature. Also remember to wash the grapes before you eat them.