During gardening season, 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 flour be stored, and is it safe for home canning like fresh produce? Let’s talk about it!

There are canning myths that canning flour in the oven will 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 that’s 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, which increases the risk of the jar shattering.

Dry canning in an oven may lead to a serious foodborne illness like Salmonella and Clostridium botulinum, also called botulism. 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 cause foodborne illness. 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, for best quality flour can be stored in the pantry, refrigerator, or freezer for:  

Pantry:
Whole Wheat Flour-3-6 months
All Purpose Flour-6-8 months 

Refrigerator after opening:
Whole Wheat Flour-6-8 months
All-Purpose Flour- 1 year 

Freezer:
Whole Wheat Flour-1 year
All-Purpose Flour-Indefinitely 

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 in the pantry. If you have questions about storing food, please call the local Extension office or download the USDA FoodKeeper App on iPhone or Android devices.  

Source: Lisa Peterson, MS Nutrition and Wellness Educator serving Christan, Jersey, Macoupin, and Montgomery Counties.