What happens when you ‘ferment’ food and how does it help with preservation?
In: Chemistry
Different kinds of microbes (bacteria, yeast, mold, etc) usually don’t like each other (for the most part). They are constantly trying to kill the other unrelated organisms around them so that they can procreate the most. Usually, over time, one of the microorganism families will become the most successful, and dominate the area.
Fermenting food on purpose usually involves attracting/directly applying a type of microbe that is safe to eat, and trying to encourage it to become the winner of the battle. There are different ways to try and encourage a winner, and it depends on what that microbe likes. Common ones are making the environment salty or acidic, removing all the water (drying), and putting it in a sealed container to cut off all the air supply (because some require oxygen to grow).
Then once you’ve got a winner, the winner microbes will start to multiply like crazy and eat the food and produce waste, which further kills the competitors and changes the taste of the food.
Some microbes will produce acid and make the food sour (sourdough bread, vinegar), some will make alcohol (beer and wine), others can produce antibiotics that specifically kill bacteria (blue cheese). All of these things kill the competition but don’t bother the microbes that produce it (at least for a while). Eventually they will either eat all the available food, or they will make the environment so harsh that even they can’t live there any more.
Since you made sure that the winner is a safe microbe, as long as that keeps winning you can eat the food.
Example 1: Your grapes are going to go rotten before you can eat them all. You squeeze them into juice and put the juice in a sealed barrel. This cuts off the oxygen so anything that needs oxygen is gonna lose. You add some yeast to the barrel (giving it a head start). Yeast doesn’t need oxygen, and it eats the sugar in the grape juice and poops alcohol. This kills anything that cannot live in alcohol. This narrows it down a lot. There aren’t a lot of microbes that tolerate alcohol and don’t need oxygen. Your grape juice is now wine and probably safe for a long time now.
Example 2: You make some cheese, but it’s gonna go bad once mold starts growing on it. Most mold isn’t safe to eat, but you have some edible mold. You intentionally get it all over the outside of the cheese wheel. It gets super moldy, but at least you know what kind of mold it is so you can still eat it. You created blue cheese.
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