Tomatoes keep best unwashed at room temperature and out of direct sunlight. It is not recommended to refrigerate them as this can harm the flavour. Tomatoes stored cold tend to lose their flavour permanently. Storing stem down can prolong shelf life, as it may keep from rotting too quickly. Tomatoes that are not yet ripe can be kept in a paper bag till ripening.Tomatoes are easy to preserve whole, in pieces, as tomato sauce or paste by home canning. They are acidic enough to process in a water bath rather than a pressure cooker as most vegetables require. The fruit is also preserved by drying, often in the sun, and sold either in bags or in jars with oil.