Concern for food safety

While they may look like easy gifts to give, you don't want to give the gift of foodborne illness. Bread or cakes baked in canning jars, then applying the lid, can create a low-oxygen environment. This, combined with baked goods high in moisture and low in acid, can support the growth of C. botulinum.

Canning jars are not designed to be used in the oven per manufacturer recommendations. Dry heat puts stress on the jars and can cause them to break. The best options? Use ovensafe baking pans for baked goods. Freeze baked goods for later use.

The actual process of baking bread or cake in a jar is not canning; the product is baked in an open glass canning jar and then covered with a canning lid upon removing from the oven. There is no further canning process applied afterwards.

The bread and cake recipes may call for the addition of fruit, liquids or vegetables, which increases the moisture content, making a rich environment for microorganism survival. In addition, the practice does not remove all oxygen, leaving some oxygen available in the jar for microorganisms to thrive.

Using this technique to preserve breads and cakes is not recommended. Many cakes and quick bread recipes often have little or no acid resulting in a pH range above 4.6. A pH of this level will support the growth of pathogenic organisms that cause foodborne illnesses. There is a great concern about the hazardous bacterium called Clostridium botulinum (botulism) growing in these jars after the item has been baked. Botulism is often a fatal foodborne illness. There are reported cases each year of individuals who encounter botulism poisoning through improper canning practices.

Several studies over the years conducted by many universities have shown that some bacteria are heat-stable and can survive the baking process and then multiply in the bread during storage.