Genie, your most recent post reminded me of some other observations.

Vegetable oils exposed to oxygen do, ultimately, get oxidised and we notice it in many as becoming "rancid". You may well be right about Melaleuca Inc's use of an expiration date to increase turnover rates but they may have also been motivated in part by avoidance of such notions. I suspect tea tree oil would take more than most people's lifetimes to go "off" but don't know any data. However, if you restrict the access of oxygen to an oil you effectively retard oxidisation. In a glass bottle the process would commence as soon as it was opened and more flexible bottles (usually plastics of one sort or another) are likely to have fat-soluble plasticisers that could dissolve into the oil; keeping oxygen away from the oil is likely to be tricky.

Concerning "fresh meat", traditional butchers that I've yarned with, over the years, can be quite dismissive of "housewives who want only the freshest of meat". Pardon the sexism but that was how it was usually expressed by these blokes. They weren't referring to chicken, fish or "offal" (the things like liver, brains and sweetmeats that "modern" sensitivities disparage); they were referring to good muscle tissue from beasts that produce red meat.

They maintained that the best steaks came from carcases that had been chilled (but not frozen) and hung for at least six months; Aberdeen Angus was (at the time) their preferred breed and the hanging was to allow the enzymes in the muscle fibres to have enough time for autolysis to properly tenderise the meat. A carcase that has been so treated will gradually go black on the outside and this has to be cut off and discarded, which takes time, higher skill levels, and diverts some tissue from the steak part of the food chain. These requirements, plus the overheads required for such longterm storage, mean that such steaks are rather more expensive than the cuts you buy in the supermarket (which may have been prepared with less attention to the detail required for "longterm" storage.

But the meat we had down at Mawson (admittedly hung in the "freezer where it could be kept "warmer" than outside with the ice) was lovely and tender and suffered no "freezer burn". And the comment above yours, about the storage of eggs, reminded me that when I was duty cook in September of that year I asked the real cook how many eggs we had to last until the Nella Dan returned. 1200 dozen was his answer, so I cooked omelettes for the 28 of us that Sunday. I have no idea how many we'd taken down but I asked him how many had gone off since they'd arrived (we'd left Oz in December; "Six!" was his reply. And they'd been kept in the "warm store", effectively at the same temperature as the main compartment of an ordinary domestic fridge. The main risk for eggs in fridges is they dry out due to the low humidity; the warm store had controlled humidity which kept them (and other things) from drying out.

Cheers, Rowan