How do you think non-acidic foods such as meats and fish are "canned"??
They're loaded into giant pressure cookers for processing.

Julia Altshuler wrote:

Aurrggh! I don't know if this guy means to be funny or not, but NEVER
heat any unopened can! In fact, this one should go in the kitchen myths
thread. I don't know where people got the idea that heating condensed
milk in the can makes caramel, but it is a bad idea. One of the brands
has even started printing warnings on the label.

And while I'm at admonitions, why the unrelated cross posts? (I erased
them.)

--Lia


Vox Humana wrote:

The easy way to make Dulce De Leche is to put an unopened can of
sweetened
condensed milk into a small pan. Add water to bring it to about 3/4
the way
up the can. Bring to a boil and simmer for about an hour. Let cool
completely before opening. You can turn the can over after 30 minutes.
Store in a jar or plastic container. It should keep for a couple of
weeks
in the refrigerator, maybe more

A quicker method is to use a pressure cooker. Cook at pressure for 30
minutes -- 45 minutes if you want it darker.