The majority of food preservatives fall into this category, for the simple reason that tiny creatures eating and spoiling our food is, and always has been, a very big problem. As I mentioned in the last post, all of the classic preservation techniques are bug-killers. The problem with them is that each radically alters the taste, and usually the texture, of food. Modern preservation methods seek to minimize these sorts of effects, so as to preserve not only the substance of the food, but the original experience of it.
Propionates (derivates of propionic acid) are a family of antimicrobials common in the baking world. Propionates occur naturally in a range of fruits and grains, and are great at killing molds. Benzoates (benzoic acids) are also found naturally in many berries, in prunes and in spices like cloves, anise and cinnamon. Also tea. They’re great at killing fungus. Sorbates come from most of the same sources and do many of the same jobs.
Sulfites are some of the most commonly used antimicrobials for two reasons: because they’re good against lots of critters (including bacteria) and are multi-taskers, doing a variety of preservative jobs (more on them in subsequent posts). Sulfites also occur widely in nature, in bananas as well as in grapes, onions and garlic. Like glutamate, they’re also a by-product of fermentation, so wherever you find yeast, you’ll find sulfites in some measure. A small minority of people in the world are allergic to sulfites, but the vast majority of us can eat them with no adverse affects.