Are preservatives or other chemicals added to canned tomato products during the canning process?

Canned tomato products contain no preservatives. Because the food in  the  cans is cooked at high temperatures and sterilized in vacuum-sealed steel containers, nutrients are kept in and impurities out.  Water, seasoned liquid, or oil is added for flavor and for fill to create a tight vacuum. In addition, citric acid is added to preserve flavor and prevent oxidation of sensitive vitamins. Calcium chloride and sodium can be found in canned tomato products, too. The calcium chloride helps whole and diced pieces stay firm and keep their shape and is also a nutrient. Although salt (sodium) does also have a preservative quality, its presence in canned tomatoes is mostly for flavor. For sodium-sensitive people, low-salt and salt-free varieties can be found.
 
Source(s):
Susan Brewer. Ph.D. University of Illinois, Department of Food Science and Human Nutrition
Jewel Food Store, Niles, IL, shelf research