Fresh cranberries are one of two berries native to North America (blueberries are the other indigenous fruit); what distinguishes the cranberry from others is that they grow on evergreen bushes with trailing vines in bogs – or bodies of water. When ripe, the berries are buoyant and float on the top of the water, attached to their plants. When harvested fresh the cranberries are round and firm like small marbles and are a bright red color with a sheen, when raw they have a very tart flavor. Much like rhubarb, cranberries must be cooked to be edible and are they not particularly palatable when raw. Classically cranberries are cooked with sugar and other seasonings the make them appealing and with their tart flavor, they are a great balance to rich holiday fare.
The North American cranberry, Vaccinium macrocarpon, is the fruit that's recognized by the U.S. Department of Agriculture (USDA) as the standard for fresh cranberries and the cranberry juice cocktail. The European variety, which is grown in parts of central Europe, Finland and Germany, is known as Vaccinium oxycoccus. The European variety is a smaller fruit with the same anthocyanin pigment in the North American variety but it has a different acid profile in terms of the percentages of quinic, malic and citric acid levels present. This fruit is commonly known as lingonberry or English mossberry in Europe.
When sourcing fresh cranberries, avoid berries that are shriveled or pale in color. A great test of freshness is to "bounce" a cranberry off of a hard surface; if the berry falls flat, it is "soft" and not as fresh as it could be. If you purchase more fresh cranberries than you can use, they freeze well and can be used later for cooking like any frozen berry. Harvested traditionally in the fall from mid-September through November, winter is the season for cranberries in North America.