Most of the flavor resides in the skin. Black Hamburg grapes, grown in hothouses, are fat, juicy and very fragrant. Concord grapes, blue-black with a dusting of silver. are eaten out-of-hand and used in jellies and juices.
Choose grapes that are plump, full-colored and firmly attached, with no brown area at stem connections. Store grapes, unwashed, in the refrigerator for up to 1 weel. Grapes also may be frowns for up to 1 week. Wash, pat dry and place in a single layer on a baking sheet. Freeze for 1 hour and them put grapes in an airtight container.
Wash grapes thoroughly before use. Ideally grapes should be served at 60 degrees F.