Is Canning Flour Safe?
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BY LISA Peterson, MS
Extension: Nutrition & Wellness
During gardening seasons, Americans home can fruit and vegetables to store them at room temperature and enjoy them throughout the year. Fruits and vegetables go bad much quicker than dry ingredients such as flour, but how long can you store flour, and is it safe to can them too? Let’s talk about it!
You may have heard of canning flour in the oven to make it last 30 or 40 years; this practice is unsafe. This is commonly called dry canning and does not work the same as canning fruits in a boiling water bath canner or pressure canning green beans. Time and temperature are critical when canning to destroy harmful bacteria and why using a scientifically tested recipe is so important. Currently, there are no safe recipes for canning dry ingredients in the oven and no research to support that canning flour in the oven will extend its shelf life. Mason jars are also not designed to be heated in an oven, and you risk the jar shattering.
Dry canning in an oven may lead to a serious foodborne illness like Clostridium botulinum, also called botulism or Salmonella. All food has moisture or water, even dried food. When dried food is put in a closed jar in the oven, the moisture moves up to evaporate but some pockets of moisture may be present. The moisture pockets in sealed jars may produce spores or mold that could make you sick. Additionally, nuts and whole grains that are dry canned may go rancid faster due to oxidation during heating.
So, if dry canning is out, how can you extend the shelf life of flour? According to the United States Department of Agriculture, whole wheat flour will keep 3-6 months in the pantry and 6 to 8 months if refrigerated after opening for best quality. All-purpose flour will keep up to a year in the refrigerator for the best quality. For freezing, all-purpose flour keeps indefinitely, and whole wheat flour for about a year for the best quality. Whole wheat flour contains oil in the germ, which goes rancid faster than all-purpose flour. Generally, store all flour in an airtight container in a dark, cool, dry place. If you have questions about storing food, please call the Jersey County Extension office or email Lisa Peterson, Nutrition and Wellness Extension Educator, at lap5981@illinois.edu
