I'm a chocolate truffle maker, and promote my product as a fresh product, no preservatives. Lately I'm getting requests for boxed truffles, which will require a longer shelf life, so I'm considering the preservative issue for the boxed truffles only. Trouble is, I don't know what a "preservative" really is, where to get it, how to use it. I've heard of so-called natural preservatives, but don't know if they really work. Does anyone out there know about preservatives for longer shelf life? Thanks in advance.