At last month's Masters of Social Gastronomy, we reached down deep into the world of preservatives, figuring out what all of those unpronounceables are on everyday packaged foods.

Today's recap: Calcium Propanoate

If you eat store-bought bread, you're probably chowing down on some calcium propanoate. It's a mold and bacteria inhibitor that keeps your bread from being conquered by legions of decided untasty microorganisms.

The bread industry's worst enemy is a little bacteria called Bacillus mesentericus. Looks something like this:

Fun, right? Bacillus mesentericus causes a condition called "rope," which makes your bread - you guessed it! - ropey. Trying to pull your bread apart only separates it into rope-ish strands, like a very sad accordian. Does not sound tasty.

The worst part about B. mesentericus is that it doesn't just settle on fresh-baked bread, it lives inside already. It's already there when you've made your dough, and is able to survive the baking process. Once the bread hits the shelves, it's a rope time bomb. If you don't eat the bread, B. mesentericus will.

But hey, that's what calcium propanoate is for! It puts the bacteria to sleep for a couple weeks, so instead of getting nice ropey bread in a couple days, you can take your time cranking out PB&J's.

Note that calcium propanoate doesn't kill the bacteria it's fighting against, just prevents it from producing energy. Not sure if that's comforting or not!

A big question with preservatives seems to be WILL THESE PRESERVATIVES GIVE ME CANCER AND MAKE ME DIE TOMORROW? With calcium propanoate, the answer is a big ol' nope.

Scientists took some rats and started feeding them calcium propanoate, just to see if anything bad would happen. And not just a tiny bit here and there - four percent of the rats' diet consisted of calcium propanoate. That's like you sneaking into my fridge and replacing the ketchup with a block of chalky preservatives.

So what happened to these rats? Nothing. Absolutely nothing. They kept the experiment going for a year and the rats were just as healthy, wealthy and wise as the control group. Now, injecting CP right into their brains was an unpleasant experience, but let's just keep these things on the dinner table.

Some people insist that calcium propanoate gives them headaches and emotional ups and downs, but you've gotta look at what they were eating at the time: Wonderbread and friends. Eating processed white bread causes your blood sugar to spike, and between that and the resulting crash you aren't looking at a Good Time.

Horrific, I know. Blame the bread, not the preservatives. Is that my cue for a Scott Pilgrim clip?

VERDICT: Calcium propanoate is a super safe preservative, and does a good job protecting baked goods from all sorts of nasties. Keep up the sandwiches!

Secret note: Calcium propanoate works against all sorts of fungus and bacteria, but it looks like using a sourdough starter might be just as effective at extending bread's shelf life.