Braising concentrates and heightens flavors and is appropriate for more robust variety meats such as tongue, heart, liver and kidneys. A low, even temperature is important during cooking, and meats are generally left whole so that they retain their juices. Tender meats such as kidneys and liver are cooked until just pink and moist in the center; others need to be thoroughly braised to tenderize. Red wine, Madeira, Marsala or port is added to intensify the flavor of a braise. Toward the end of cooking a garnish of small onions, mushrooms, truffles and bacon may be added. Fruit such as orange, raspberry, red currant or raisin can give the sauce an agreeable tang, but meats like sweetbreads are better suited to a lighter addition, such as white wine.