Why do we eat spoiled food?
Some of our very favorite foods are closer to this than this. That’s because coffee, bread, cheese, beer – even chocolate! – are home to millions of microbes. In fact, these foods only acquire the tastes, smells, and textures we love because of tiny bacteria and fungi. The vast majority of microbes – about 99% – are actually quite harmless to humans. But the other 1% are nasty enough that our ancestors – and the ancestors of various other mammals and birds – evolved a natural repulsion to stuff that might harbor nasty germs. In general, we think rotten stuff looks and smells disgusting, which, considering what's at stake, isn’t overly cautious. Fortunately, if friendly microbes get to our food first, they can keep the bad guys at bay. Meat left out on the counter provides the perfect conditions for pathogens to flourish: it’s warm, moist, and protein-rich, just like our bodies. But with some micromanagement – adding lots of salt, for instance – we can help harmless, salt-tolerant microbes like Lactobacillus outcompete their dangerous but salt-sensitive relatives. A few unrefrigerated months later, we get salami, rather than Salmonelli! Our ancestors stumbled on this kind of controlled spoilage thousands of years ago – either by lucky accidents or out of serious desperation – and we humans have been intentionally spoiling food ever since. Not only to keep our food safe to eat, but also because the microbes we culture can transform it, almost magically, into awesome deliciousness. Yeast, for example, gorge on the sugary starch in bread dough, then burp out carbon dioxide that helps give loaves their lift. In a more exotic transformation, bacteria and fungi take turns munching on piles of cacao, mellowing out bitter polyphenols and helping create the complex and delicious taste of chocolate. And deep in cheese caves, mold spores populate small holes and cracks in soon-to-be blue cheese, while their relatives munch through the rest of the blob, digesting big protein and fat molecules into a host of smaller aromatic and flavor compounds, that give the final product its smoothness and rich, funky flavor. But to some, stinky cheese is about as appetizing as licking someone’s toes. Which isn’t that far off, since the bacteria that make some cheeses super-stinky are the same ones that cause foot odor. Yum? Even so, these flavors tend to grow on us: not just literally but also figuratively. The more we’re exposed to particular microbial funks – from our first taste of the flavor compounds in amniotic fluid forward – the more we tend to like them. As a result, people around the world have some very different ideas about how to microbe-ify foods – but every culinary culture involves fermentation in one way or another. And if we didn’t let food spoil just a little bit, we’d have no sauerkraut, soy sauce, pickles, or prosciutto. Not to mention kefir, kimchi, kombucha, koumiss, katsuobushi - and plenty of other delicacies that don’t start with K. What’s more, spoiled food may well have changed far more than our tastes – historical evidence suggests that, when our ancestors gave up their wandering ways and settled down to grow grain, it was likely for love of either bread or beer. Whatever the case, one thing is clear: without the help of friendly fermenting microbes, we humans would be terribly uncultured.