I've tried pasteurized and from concentrate. It should surprise nobody that those don't really grow things, but then I store both types in whatever carton they come in or that I decant them into (I had bottles for the squeezed orange juice). I kept neither completely open in the fridge, as that makes everything smell like orange juice and the orange juice itself taste like fridge.
If your question is merely why yours only lasts a couple days when mine lasted a week, it might've just been due to a difference in air contact or something, since in my case I think I pretty much filled a glass to the brim, put plastic wrap over it, and left it like that in the fridge for a week. I think my goal in that particular experiment was just to show orange juice doesn't inherently need special treatment to last that long.
But I thought the whole debate here is whether they're doing something to commercial juice that's different from what you get when you squeeze your own. In which case... shouldn't you be comparing home-squeezed vs. the store-bought ones that are not pasteurized or from concentrate? The ones that are claiming they're absolutely nothing but just squeezed orange juice? If the label already says it's been treated differently then there's nothing to investigate...
I will readily admit that I don't believe such a juice exists in any shops close to me. Anything that claims to be fresh is from concentrate, pasteurized or barely the juice that it claims to be (eg 90% apple juice, 7% the juice that you want, 3% unaccounted for).
Ah I see. It depends on where/which country you are I guess. As a couple examples, if you're somewhere with a Target, Simply Orange [1] claims to be pasteurized, whereas Tropicana does not [2], and neither is from concentrate. Although it's possible they both are pasteurized and the labeling isn't required... I don't know if it is.
However, if your next-best option is pasteurized juice, that sounds... just fine, if not even better? I mean I hope you're not finding pasteurization a horrifying Big Ag conspiracy of some sort. And pasteurization seems like a pretty plausible explanation of the difference you see compared to what you squeeze yourself... so then what's the huge worry?
