If you have seen separation in your home canned tomatoes, you may be wondering just what causes this to happen. Heating the product before putting it in the jar; otherwise known as a hot pack can help prevent this separation.
Separation in canned tomato products is not unsafe. It merely reflects the action of enzymes in tomatoes that have been cut and allowed to sit at room temperature. The enzymes that naturally occur will begin to break down pectin in the tomatoes. This breakdown results in a yellow red tinted liquid that can appear in either the top or bottom of the jar. In tomato juices, a quick shake of the jar will make the layer disappear. The layers will reappear after the contents of the jar resettle. In canned whole tomatoes, the separation cannot be dispersed by shaking the jar. You can safely use both the tomato layer and the liquid layer while making other foods like spaghetti sauce or chili but it is a bit unappealing in the jar.
Be sure to follow the directions for the hot pack carefully as overheating the tomatoes can also cause separation of the solids and liquids. Our favorite recipe for canning tomatoes is from the National Center for Home Food Preservation.
Enjoy the rest of tomato season!