I also think this should be brought up in this discussion. This is only about the berries being able to be dispelled or not.

Are the berries magical once produced and up until they lose potency?

If they are they are subject to dispel magic, unless they are catagorized like magic weapons/armor and can not be.

If they are not then how do they then deliver a full days rations and healing? Is there an in world berry that provides the same benefits that this spell is conjuring from?

My point is this these berries while summoned by an instant duration spell are in fact magical until they lose potency. They should be subject to dispel magic.