By Sam Sifton Makes about 2 cups Cranberry sauce should be sweet but not cloying, and tart without causing pucker and anguish. It should have a jellylike quality, but should owe more to the appearance of jam. The key element to making cranberry sauce is to understand that cranberries are high in pectin, a carbohydrate that exists in many fruits and is released by the berries when they are heated and the cells of the fruit break down. In the presence of sugar, the pectin molecules bond to one another, forming a kind of gel. The longer you cook a cranberry sauce, the more pectin is released and liquid is evaporated, and the stiffer the result will be.