Canning low acid foods in an 240° oil bath...crazy, stupid or possible?

[ushwickgirl]

This was a recent query on chowhound.com.  A number of posters responded and think it's nuts, as do I, but one poster in particular seems to need the scientific explanation as to why this is doable or not. Temperature wise, sure, you can get oil up to 240° or 250° for processing, but what happens next? 

Yes, you read this correrctly, canning low acid foods in a 240° open cooking oil bath, rather than with water in a pressure canner. 

Thoughts?/img/vbsmilies/smilies/surprised.gif

 

[phatch]

Terrible idea. Canned items aren't sealed in the bath, they seal afterwards as they cool. So it will boil out into the oil causing problems as well as oil getting in the jars, ruining the seal. The jar contents still boil at the standard boiling temp. This will drop the oil temp and spatter and other problems.  The contents temp won't rise above boiling until the water content is gone, ruining whatever you're canning.

And it's not just the temperature, the pressure also helps. With the pressure, the jar contents don't boil until they're  at the boiling point of the extra pressure.

 

[kyheirloomer]

Another aspect to consider. Pressure canning is designed to destroy specific microbes (particularly boutulism bacteria). To accomplish this, the contents  must be brought to a minimum of 240F, and held at that temperature for a set time period.

There is no guarantee, with the oil, that the contents will have even reached that temperature all the way to their center, let alone be held there for the required time frame.

Phil: Why would the contents boil over in 240F oil any more than in 240F steam pressure? The whole idea of headspace is so that air can vent out without carrying the contents with it.

 

[phatch]

Well, maybe not a boil over, butI see  problems. There is often some burping of liquid from the jar. Not lots true, But in the oil situation, the liquid is isnot going to react well in the oil as it would just disperse in water.  And I predict a lot failed seals from oil on the sealing ring.

 

[petemccracken]

I don't believe water can exceed 212°F at atmospheric pressure, hence the need for a "pressure canner", to increase the pressure and raise the boiling point above 240°F.

As stated previously, the oil might be at 240°F, but the contents of the jar will not rise above 212°F until ALL the water has changes to steam

 

[maryb]

Water under pressure will NOT turn to steam at 240 degrees, that is how a pressure canner works. The contents of the jar wind up at the same pressure so the boiling point rises.