If I use biological samples as an analogy to food (probably not unreasonable, since what makes food go bad is similar to what makes biological samples degrade):
We have three kinds of frozen storage:
(1) Regular freezer temperature (-20C); however, we prefer frost-free freezers because automatic-defrosting freezers cycle their temperature. Some compounds may be sensitive to moisture so they also get put in a dessicator (sealed container with a drying agent), but you wouldn't want that for food. Others may get tightly sealed to prevent water from sublimating -- this might be useful to food storage, and heat-sealable bags haev already been invented for this purpose.
(2) Ultra-low freezers. These are typically at -80C. They draw a lot of current (typically have a dedicated circuit), and moreover usually need 220V, and they are very expensive. And also noisy (constant hum of a big compressor). Biological samples that may go off after a few months at -20C will typically last years in one of these. I would guess the shelf life of meat kept at -80C would be close enough to forever for your purposes, if it was kept from drying out.
(3) Storage under liquid nitrogen. This is about -190-ish C. Also tends to purge oxygen from samples. Storage is pretty simple -- basically a big Dewar (thermos bottle) but it does need to be refreshed periodically.
There are a couple of things that make food go bad. One is microbial growth. Freezing retards growth (not necessarilly killing it). Cooking kills bugs, too, but if you want to guarantee complete sterilization food may get cooked more thoroughly than you may find it acceptible for some items. Pressure cooking cooks things at a higher temp than the boiling point of water, and thus may destroy spores that are heat-resistant (which is why autoclaving is favored for laboratory and medical sterilization). Irradiation will also destroy microbes; some people (not me) have a problem with irradiated food, and for home use it would be impractical.
The second thing that makes food go off is fatty acid oxidation. This is what makes fats go rancid, and happens independently of microbial growth. This can be countered either by preventing oxygen from reaching the sample, or by adding anti-oxidants, or both.
If I wanted to hypothetically keep food for a long time at higher temperature (room temp or slightly warm) and money was no object, I would cook it, vacuum seal it after purging oxygen from the sample, and also adding anti-oxidants, then irradiate the bejeebers out of it. I probably wouldn't keep it at cooking temperature, because heat will continue to break down biological molecules.
Or maybe just use one of those Slaver stasis boxes from Larry Niven's
Known Space universe.
Nick