The Disquieting Delights Of Salt-Rising Bread
How Clostridium, a nasty pathogen, makes an infectiously delicious confection
I've recently come across a french fermentation method that, unlike the breads and brews and yogurts and pickles and misos we know and love, isn't run by the usual benign microbes. The engine behind this fermentation method is Clostridium perfringens, a close relative of bacteria that cause botulism, tetanus, and food poisoning. It can eat flesh. It gives gas gangrene its name by causing putrefying flesh wounds that bubble and foam with flammable hydrogen. And it can make something surprisingly delicate and tasty.
As befits a nasty pathogen, Clostridium perfringens grows aggressively. Its cells can divide every ten minutes, a handful turning into trillions of hydrogen makers overnight. That hydrogen gas can leaven dough just as yeast-generated carbon dioxide does. The result is something known as "salt-rising bread." A century ago, a scientist went so far as to bake bread leavened with Clostridium perfringens drawn from an infected wound, in what the West Virginia Medical Journal called "perhaps the most macabre experiment in culinary history."
And so I present to you an all-you-can-eat story not about the limits of stomach capacity, but about the far shores of edibility.
This curious flavor variability in salt-rising breads comes at least in part from variability in the microbes in the flour and cornmeal that we select to do the fermenting. And the selection process is pretty drastic. You notice that the recipe starts with scalding-hot liquid poured onto the dry ingredients. This step kills all of our familiar friendly yeasts and lactic acid bacteria, and, in fact, most microbes of any kind. The survivors are those bacteria that happen to be present as dormant and tough spores, which are actually stimulated by the high heat to germinate when the temperature drops back down to livable levels.
Does that situation ring a warning bell? It should. The standard recipe for salt-rising bread instructs us to do something we're warned against in the name of food safety: leave thoroughly cooked foods to sit in a warm place for hours. Cooking kills bacteria that are already active, but spores survive and are stimulated to grow -- and grow fast -- when the food temperature drops from piping hot to warm. That's exactly how Clostridium perfringens ends up being a common cause of food poisoning. And yet in salt-rising bread we make a point of encouraging it.
Read it here: http://www.popsci.com/article/science/cl...-you-bread