We don’t usually get sick from eating fermented foods like kefir and Kimchi, and it is known that there are some health benefits from eating them for our gut health. BUT we often get sick from drinking spoiled milk or eating rotting meat and vegetables. What is the difference between food being “fermented” and food being “spoiled”?
In: Biology
Good bacteria vs. bad bacteria. Fermented foods are infused with healthy bacteria which out-compete the bad stuff.
The bacterias and fungi in the food are the difference. Fermented food uses specific strains of fungi or bacterias that we know will not produce dangerous byproducts. When food spoil, you have no control over what grows in it and there is a high risk of being something that will make you sick. Sometimes you may be ok eating spoiled food but you are rolling a dice.
Fermented is just spoiled in a way we find favorable and that doesn’t make us sick.
It’s kind of like the difference between a weed and a flower.
Fermentation is the breakdown of carbs into other substances, such as alcohol, whereas spoiling is bacteria eating the food and leaving behind waste that makes us sick, or fungus eating the food and growing unchecked.
The difference between “fermented” and “spoiled” is similar to the difference between a salad bed in a garden, versus a wild meadow.
In a garden, we plant specific species of crop plants that we know are edible and taste good. We know that there’s nothing poisonous there because we planted them all ourselves.
Whereas, if you just wandered into a random meadow, grabbed a handful of leaves and started chomping on them, some of them might be poisonous and even if they aren’t, they will still almost certainly not taste good.
Spoiled food is like the wild meadow. It’s when the random set of microbes that live wild in the world, start growing in our food. Fermenting food is when you plant specific microbes, and let those grow. *Those* can make tasty things.
The difference is mostly about control. When food spoils, bacteria, molds, and fungi rage uncontrolled throughout the food. Some of these are inedible, while others produce inedible or even poisonous byproducts. You don’t want to eat rotten food.
When foods are deliberately fermented, only certain kinds of microorganisms are allowed. This requires you to start with *very* careful cleaning and saniation practices, essentially eliminating any microorganisms that might already be in the ingredients, then deliberately introducing the kinds of microorganisms we want and nothing else. By controlling the process this way, we can ensure that the food remains edible and transforms into the new food we want, rather than just decaying into inedible rotten food.
So when we ferment food we add microorganisms to it which break it down in a way that provides substances that are beneficial, or at least non-toxic, to us. When food is spoiled or has “gone off”, that’s when microorganisms, such as bacteria or fungi, have grown on it and started to produce chemicals that make us feel ill. Some microorganisms produce waste products that are toxic to humans and these aren’t broken down when you cook food, they stay there even though the microorganism itself has been killed
– Biology Teacher
True ELI5: **The difference is what little critters are eating the food, and whether their poop is delicious or poisonous.**
Bacteria and microbes aren’t all one thing. There are hundreds of species. Some are harmless or even change food in tasty ways, while other species can make you very sick or poop out chemicals that can make you very sick.
* Yeast east sugar and pees alcohol, so when you “ferment” beer, you’re deliberately adding the yeast microbes because you want them making your sugary grain water into alcoholic beer. When you make cheese, or soy sauce, or anything else fermented, you’re deliberately adding a microbe whose poop you want to eat.
* Other microbes like botulinum poop toxic garbage, so when *they* eat your food and poop in it, we call that food “spoiled” because it’s sickening rather than better-tasting.
With fermentation, we’re looking to grow a specific kind of bacteria (usually lactobacillus). The idea is to create an environment that is so hostile to other bacteria that it allows the culture you’re trying to grow to outcompete other cultures that might be dangerous. We usually use ph to test this. Anything more acidic than 3.5 will typically be what we’re aiming for, and with lactoferments we’re usually looking to use salt to accomplish this. Lactobacillus puts out lactic acid as a part of its lifecycle, which keeps the food acidic and hostile to occult flora. The fermentation means that cultures that are unsafe to eat are being outcompeted by stuff that is safe to eat.
On the other hand, just letting whatever grow means you don’t have any knowledge of what might be growing in your food, or what it’s excreting in the process of its lifecycle. That makes it potentially dangerous.
Lactic Acid producing bacteria can be quite common. Regarding Kimchi, and Sauerkraut, we don’t need to specifically add bacteria.
It’s all about the environment. Salt is added. It’s also fermented in an environment with little oxygen. This controlled environment is great for the bacteria we want.
During the process the acid producing bacteria also help control the environment.
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