Why is the processing time in a boiling-water canner for tomatoes canned with tomato juice or with no liquid added so much longer than for tomatoes canned in water?
The more solids present in tomatoes, the lower the acid content. Also, when tomatoes are crushed down to form their own juice, it's very much like a dry pack--very dense--making heat penetration slower. Tomatoes canned in water are actually higher in acid. That's why it's safe to process them for shorter periods of time.
Barbara Willenberg, Nutritional
Sciences, University of Missouri-Columbia
Last update: Tuesday, May 05, 2009