Canning cheese spreads?

Canning cheese may carry with it a risk of botulism, according to Clemson University Extension and the National Center for Home Food Preservation. Soft cheese is of particular concern.

This practice has not been scientifically validated and we cannot recommend it. Cheese and cheese milk can potentially be contaminated with Clostridium (C.) botulinum, the botulism-causing bacteria. The pH of cheese qualifies it as a low acid (pH 5.1 to 5.9) food and thus is in the canning danger range. Although uncanned hard cheeses (Asiago, Cheddar, Edam, Feta, Gouda, Parmesan) will not support growth of C. botulinum, the canning process may add available water to them. How much water is added by canning has not been tested. Increased available water may allow C. botulinum to grow and make canned hard cheeses unsafe. In addition, boiling waterbath canning processes kill the competitive “good” bacteria that help prevent the growth of C. botulinum. It is the dryness (low available water), salt content (lowers available water), acidity (produced by lactic acid bacteria) and competitive “good” bacteria that provide safety for hard cheeses; because of these factors, they can be waxed and stored for aging for years on the shelf without safety problems.

The incorrect assertion that it is possible to safely can soft cheeses such as cream cheese is of major concern. Soft cheeses are higher in available water and must be refrigerated to delay spoilage. They contain sufficient available water to support the growth of botulism-causing bacteria. A boiling waterbath canning process does not kill spores; therefore, canning soft cheese clearly raises the potential for serious health problems.

So, until more testing is done by a very reliable source, I would consider canning cheese to be unsafe. At least I wouldn't consider it to be shelf stable.