Canning At Altitude: Adjustment Guide - Granite Ware F0730 Instruction Manual And Users Manual

safety. The time needed to destroy bacteria in low-acid canned food ranges from 20 to 160
minutes. The exact time depends on the type of food, the way it is packed into jars, and the
jar size. We suggest you always follow the most recent USDA recommendations. The
National Center for Home Food Preservation has a complete listing of current USDA
recommendations at http://nchfp.uga.edu/publications/publications_usda.html
During pressure canning, water in the canner is converted to steam, which creates pressure
within the canner. As pressure increases, so does temperature at this scale:
0 psi
212°F (100°C)
To get the temperature required to kill harmful bacteria, steam under pressure needs to be
created. After the canning process when the jars cool, a vacuum is created sealing the food
inside and preventing any new microorganisms from entering and spoiling the food.
If using store bought canned foods in your food preserving process, boil all low-acid foods
including tomatoes for 10 minutes at altitudes below 1,000 feet. Extend the boiling time by 1
minute for each 1,000 foot increase in altitude. This is a good safeguard against spoilage not
easily detected in canned goods.

CANNING AT ALTITUDE: ADJUSTMENT GUIDE

If canning above 1,000 feet in altitude, adjustments must be made to either the processing
time or the canning pressure to ensure food safety. Using process time for canning food at
sea level may result in spoilage if you live at altitudes of 1,000 feet or more. Water boils at
lower temperatures as altitude increases. Lower boiling temperatures are less effective for
killing bacteria. Increasing the process time or the canner pressure compensates for lower
boiling temperatures. Therefore, you must select the proper processing time or canner
pressure for the altitude where you live. If you do not know your altitude, contact your local
county Cooperative Extension agent.
service provided by the United States Department of Agriculture (USDA).
Pressure canners need an additional 1/2 pound pressure for each 1,000 feet elevation above
sea level according the USDA. Water-bath canning requires 2 additional minutes processing
time for each 1,000 feet above sea level.
At different elevations, pressure canning processing time stays the same, only the weighted
psi required changes.
Altitude in Feet
0 – 1,000
Over 1,000
5 psi
220°F (104°C)
http://www.csrees.usda.gov/Extension/
Altitude Adjustment for Pressure Canner
10 psi
235°F (113°C)
Pounds Weighted Pressure (psi)
10
15
15 psi
250°F (121°C)
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