Most prunes will have potassium sorbate added as a preservative (prevents mold). Non-sorbate ones are just the dried plums, no added preservatives. Thus, buy in smaller batches as they won't have as long a shelf life.
I typically buy Trader Joe's Non-Sorbate pitted prunes and I have to be honest, I don't know what Non-Sorbate means. Can someone help me out? They have 2 kinds of pitted prunes, ones that have sulfates and the kind I buy. Is one really better than the other?