The New Complete Book of Food
peel them, put the grapes into a colander and submerge it in boiling water for a few seconds,
then rinse or plunge them into cold water. The hot water makes cells in the grape’s flesh
swell, stretching the skin; the cold bath makes the cells shrink back from the skin which
should now come off easily.What Happens When You Cook This Food
See above.How Other Kinds of Processing Affect This Food
Juice. Red grapes are colored with anthocyanin pigments that turn deeper red in acids
and blue, purple, or yellowish in basic (alkaline) solutions. As a result, red grape juice will
turn brighter red if you mix it with lemon or orange juice. Since metals (which are basic)
would also change the color of the juice, the inside of grape juice cans is coated with plastic
or enamel to keep the juice from touching the metal. Since 2000, following several deaths
attributed to unpasteurized apple juice contaminated with E. coli O157:H7, the FDA has
required that all juices sold in the United States be pasteurized to inactivate harmful organ-
isms such as bacteria and mold.
Wine-making. Grapes are an ideal fruit for wine-making. They have enough sugar to pro-
duce a product that is 10 percent alcohol and are acidic enough to keep unwanted micro-
organisms from growing during fermentation. Some wines retain some of the nutrients
originally present in the grapes from which they are made. (See wine.)
Drying. See r aisins.Medical Uses and/or Benefits
Lower risk of cardiovascular disease, diabetes, and some forms of cancer. Grape skin, pulp,
and seed contain resveratrol, one of a group of plant chemicals credited with lowering
cholesterol and thus reducing the risk of heart attack by preventing molecular fragments
called free radicals from linking together to form compounds that damage body cells,
leading to blocked arteries (heart disease), glucose-damaged blood vessels (diabetes), and
unregulated cell growth (cancer).
The juice from purple grapes has more resveratrol than the juice from red grapes,
which has more resveratrol than the juice from white grapes. More specifically, in 1998,
a team of food scientists from the USDA Agricultural Research Service identified a native
American grape, the muscadine, commonly used to make grape juice in the United States, as
an unusually potent source of resveratrol.