I find these to be some of the most interesting preservatives, since they accomplish what most antimicrobials don’t: they keep fruits and vegetables from browning and shriveling up due to the activity of enzymes. Exactly how they do that I explained a while back in a post about sulphured fruit. Have a look-see if you’re feeling geeky. The post explains how sulphur dioxide (I told you I’d come back to that compound) works to keep candied fruit from degrading. It’s a good case study in how these sorts of preservatives function.