Canning is making a comeback and is a good way to enjoy produce year-round. However, canning needs to be done properly using a USDA tested recipe to ensure a safe product. Iowa State University Extension and Outreach offers a program for those interested in learning more about safely preserving food, Preserve the Taste of Summer. This program includes both online lessons and hands-on workshops providing the most current USDA-approved food preservation recommendations. For more information, please visit: http://www.extension.iastate.edu/humansciences/preserve-taste-summer
A. There are only two safe methods to can foods:
1. Hot water bath/boiling water bath canning
2. Pressure canning
Other canning methods, including oven canning, open kettle canning, and sealing jars with paraffin are not acceptable methods.
B. The type of canner you use depends on the acidity (pH) of the food:
Hot water bath/boiling water bath canners are to be used with high-acid foods (pH <4.6)
o These foods contain enough acid to prevent the growth of harmful bacteria (Clostridium botulinum).
o Foods include most fruits*, jams, jellies, conserves, grape and apple juice, and some pickled products.
? *Tomatoes, figs, and Asian pears require acid (such as lemon juice or citric acid) to be added to them to have a pH of 4.6 or lower.
Pressure canners are to be used with low-acid foods (pH > 4.6)
o These foods MUST be processed in a pressure canner to ensure a high enough temperature is reached to kill any foodborne illness-causing microorganisms or other toxins and spores.
o Foods include most vegetables (other than acidified tomatoes), protein foods (meat, poultry, and seafood), and mixtures containing low and high acid foods (spaghetti sauce, soup).
C. Always use USDA tested-recipes and food preservation practices
Make sure your canning recipes follow the latest guidelines. They should be based on or compatible with the 2009 USDA guidelines.
Food preservation resources: http://www.extension.iastate.edu/humansciences/preserve-resources
Iowa State University Extension and Outreach’s AnswerLine: 1-800-262-3804 or email@example.com