Shelf life of pasta.

[Moony]

I can easily get hold of 20 litre liquid barrels, they are not designed for food, But they are brand new.

I suppose I could fill one of them up with rice, Chuck in a couple of Oxygen Absorbers then screw the lid on tight, that would keep for ages.

Or is it advisable to only use plastics that are rated for food use?

Without a sealed mylar liner the 20 litre barrel isn't airtight even it it might seem so with the lid on tight. The oxygen absorbers will create a partial vacuum, which isn't a problem with mylar, but will probably bow the sides and might deform the lid of a barrel if used without a liner. Food grade or not shouldn't really matter is it is new.