Some items require a permit/license as many agri items are Gov't controlled. These are mainly granted for personal reasons or on a specific time to time basis (ie, Lamb Chops for your restaurant). Many dry goods can only be sold in bulk to the designated Belize agent (large scale importers, James Brodies, Santiago Castillo, etc...) Spirits have their own set of rules. Your best bet is to hire a customs broker and he can outline the permit process for cetain items and the expected duties and taxes applicable to imports.
Not easy but not too hard with the proper broker. I've used George Bradley in the past. Everyone has their favorite.