Many recipes circulate that recommend baking breads and cakes in canning jars. Consumers like to do this because the jar makes an attractive package for their favorite recipe. However, many do not think about the safety of this practice. These products are not shelf-stable and therefore cannot be stored at room temperature. If they are stored at room temperature, harmful bacteria could grow in them and make the product unsafe to eat.
In addition to the risk of botulism, there is also a significant risk for consumers to become injured from broken glass when baking cakes and breads in glass canning jars. Canning jars are intended for use in hot water baths or pressure canners and are not designed to withstand the thermal stresses that occur with dry oven heat.
An acceptable alternative is to make a dry mix in a jar. Place all of the dry ingredients in a jar. Attach complete directions to the jar that includes wet ingredients to add, such as eggs, oil or water along with the baking instructions. Be sure to emphasize that baking should be done in a cake pan or bread pan and not the mason jar.
Additional nutrition and health information can be found on the MissouriFamilies website.
Contributor: Maude Harris, Nutrition and Health Education Specialist, University of Missouri Extension, firstname.lastname@example.org, 573.545.3516