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...