Food safety is important when preserving produce, says K-State food scientist
Tomatoes can be preserved and packaged in many different ways and frozen tomatoes are no exception, but can they be canned?
Kansas State University food scientist Karen Blakeslee said … it depends.
“It is not recommended to can tomatoes that froze on the vine,” Blakeslee said. “This is because the acid content changes too much when they freeze on the vine, making them unsafe for canning.”
However, tomatoes harvested before the fall freeze and then frozen can be canned because they do not change acidity. Blakeslee said however, that the texture will change after canning and become very soft.
“The best choice for canning previously frozen tomatoes is to make a well-cooked product, such as a stewed or crushed tomato product, or made into tomato juice or sauce,” Blakeslee said.
Canning frozen tomatoes by whole or quarters is not recommended.
“They will pack into the jars differently, absorb moisture differently, and the heat transfers through the jars differently,” Blakeslee said. Because of these changes, under-processing and spoilage may occur.
Blakeslee reminds gardeners that tomato canning recipes are based on fresh—not frozen—tomatoes.
