Adjusting Processing Time for Your Altitude
What does it mean when your recipe tells you "adjust processing time for your altitude"? Altitude adjustment is a very important part of canning, so you need to get a good understanding of it before you dive right into canning.
Every state (or county, for that matter) has a different altitude. Since land is not flat, some of us life "up in the hills", while others live "down in the valleys". That means that the pressure is going to vary from place to place.
Here is something very important for you to remember: Altitudes above 1,000 feet above sea level must be adjusted.
The reason for this is that as you go higher and higher in elevation, the atmospheric pressure is reduced. This causes water to boil lower than 212* Farenheit.
Why does this matter?
Because if water at your elevation boils at lower temperatures, and your canning manual says to process (boil) your jars for 20 minutes....your boiling is going to be different than their boiling. This is because water at your elevation will start boiling at cooler temperatures than 212* Farenheit. This is not safe!
It takes at least 212* Farenheit to kill the bacteria contained in your jars of food; so if you process your jars in temperatures lower than that, you won't eliminate all the bacteria. Even if your jars are perfectly sealed,
botulism spores can still grow and multiply
in your jars if they have not been canned at the right temperatures!
Find Your Altitude
Now that you know why altitude adjustment is so important, you need to figure out what your altitude is, so you can adjust processing times.
The best way to do this is to Google it. Just type in your town, state, altitude and this will usually bring good results. Or you could try contacting your local extension service, as they may have information for you about this.
Found your elevation? Great. Now figure out what you actually need to adjust.
For each 1,000 feet above sea level, pressure canners need an added 1/2 pound pressure. The charts below should help you with your adjustments.
For each 1,000 feet above sea level, water bath canners require an extra 2 minutes more time.
go from Altitude Adjustment to Canning Methods
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