I know that for my area, that I should process my meat at 11 pounds for 90 minutes, but, I have a friend that processes her meat at 15 pounds for 45 minutes, and gets twice as much done as I do, and has never had a problem. What are the rules for increasing pounds of pressure to decrease the processing time?
You are correct in understanding that there is a relationship among time, temperature, and pressure in canning formulations. Higher pressure means a higher temperature which in turn decreases the amount of time you need to process the product in order to achieve adequate safety.
However, there are several other variables involved
as well - the size of the can or jar, the food in the
jar (including things like acidity, fat level, thickness
of the "brine" and salt level). It takes a team of
people (usually called process authorities) to create,
test, and validate a low acid canned food, such as meat,
for safety. There are only one or two such groups in the
United States who are qualified and willing to do this
The USDA canning guidelines (like the ones you are
following) have been carefully tested using home
processing equipment by scientists at Pennsylvania State
University and the USDA in the 1930's and 1940's. They
include a prudent margin of safety, both in food safety
and personal safety. On the other hand, they leave very
little room for modification. Most of these processes
have been reviewed in the past few years and a few have
been modified slightly, but the basic recommendations
have not changed.
I cannot recommend your friend's process system. In
fact, I cannot find a commercial process (using much
heavier equipment and multiple control techniques) using
such a high pressure for such a short time.
Your friend's process could be safe, or your friend
could be very lucky. However, the risk of an exploding
pressure canner or botulism is much too great for me to
feel comfortable with the process as described.
Douglas L. Holt, Ph.D., Chair, Food
Science and Extension Specialist, University of
Last update: Tuesday, May 05, 2009