Why do berries, fruits, and tomatoes float from the bottom of the jar?
When fruits and tomatoes float, it indicates shrinkage of foods or air entrapped in the cells of foods. The best method to prevent trapped air is to use the hot pack method. It may also occur when foods are overripe, the pack is too loose, or syrup is too heavy. The high temperature of pressure canner processing will cause these foods to float. The water in the boiling-water canner should be at a good rolling boil when jars of food are placed in the canner. This prevents foods from starting to cook before the water boils.
Barbara Willenberg, Nutritional Sciences, University of Missouri-Columbia
Last update: Tuesday, May 05, 2009