When raspberries are picked, the delicate cluster of fruits separate from the core, which gets left behind on the bush. This makes the raspberries especially fragile, difficult to ship, and, naturally, expensive. Once raspberries reach market, they have a shelf life of a day or two.
Choose berries very carefully. They are often packed in opaque boxes that may conceal inferior fruit beneath a display of perfect specimens on top.
If the box is cellophane wrapped, your best bet is to examine the berries you can see, and check the box for dampness or stains, which indicate that the fruit below may be decaying. If the box is not wrapped, you can remove a few of the top berries and peek beneath.
Raspberries should be plump, dry, firm, well shaped, and uniformly colored. Don’t purchase berries that are withered or crushed.