Emperor Grapes have large, deep-red clusters and a lasting flavor
characterize this seeded variety that was first planted in California in 1863. In East Coast cities, where European traditions remain strong, the Emperor is very popular. Emperor grapes have a mild, almost cherry flavor.

As with all grapes, Emperors are low in sodium, high in anti-oxidants, have food amounts of fiber, and are low in calories, with 70 per cup. Grapes do not get sweeter after picking, so color is the best indicator for ripeness and sweet flavor. Look for grapes that are plump and firmly attached to pliable stems. Avoid soft or wrinkled fruits.

Grapes are sold ripe and ready to eat. Refrigerate unwashed. They will keep will for up to 7 days at 38-40 degrees F. Just before service, rinse grapes with cool water.  Emperor grapes store well.

One pound of  grapes with yield 3 cups.

Here are three in-depth and excellent grape sites for information, recipes and more:

http://www.tablegrape.com/rev99/index.htm

http://www.dole5aday.com/encyclopedia/Grapes/grapes_types.html