Helpful person wrote:
>
> On Monday, December 7, 2015 at 9:39:22 AM UTC-5, Gary wrote:
> >
> > Exactly. In the enclosed container with lid, that tiny bit of frost
> > only comes from the humidity left in any air in the container.
>
> No.The frost is drawn out of the food. The reason is that at the low freezer temperature the vapor pressure of water is extremely low (in the container) which causes water to be drawn out of the food in an attempt to equalize the pressure. As the vapor is drawn out it freezes, hence ice crystals.

Maybe our difference here is with closed containers vs open?
I've kept soup, sauce, broth for up to a year in a closed container
with no problem.

An open container though goes to hell. Ever keep an ice cube tray
unused for a long time? They shrink down to nothing. I still assume
that's only because they aren't kept in a closed container. The
freezer is only sucking moisture out of the surface, not below the
surface. I've got quart water containers with tight lid on in my
freezer...they never reduce in size. Neither does food in containers.
Just like food saved in vaccumn bags last a long time.