 Food additives, food additives are substances added to food to preserve flavor or enhance its taste, appearance, or other qualities. Some additives have been used for centuries. For example, preserving food by pickling with vinegar salting, as with bacon, preserving sweet for using sulfur dioxide as with wines. With the advent of processed foods in the second half of the 20th century, many more additives have been introduced, of both natural and artificial origin. Food additives also include substances that may be introduced to food indirectly called indirect additives in the manufacturing process, through packaging, or during storage or transport.