I know tomato skins should be removed before canning as they become tough. However, if you don't mind the toughness, skins could be left on as they don't affect the pH (acid level). Would removing the skins lower the number of bacteria present?
Yes. Skin removal would lower bacterial numbers. However, as long as home canners don't use soft or diseased tomatoes, leaving skins on poses no safety problem if current recommendations for canning tomatoes are used.
Source: Personal communication with
Dr. Gerald Kuhn, Food Scientist, Penn State University,
Last update: Tuesday, May 05, 2009