No matter how you store food (unless it’s in the freezer), it always get moldy eventually. How does this happen? Mold is a fungus, and fungi spread through spores, right? So are these mold spores just everywhere all the time, looking for food? If so, then does that mean that mold is on everything we eat, but it’s just not toxic until you can see it? And why does refrigeration slow down this process?
In: 670
[removed]
Take a fresh piece of bread and press your unwashed hand into it. a few days later you’ll find that it’s getting really mouldy in the shape of your hand. Fascinating
They’re everywhere. Always.
Your average cubic meter of air has 500 mold spores and 100,000 bacteria/virus particles. The minute those spores and bacteria hit something edible they’re going to start to multiply.
You can delay it (freezing, drying, smoking, salting/sugaring to create an osmotic effect etc), fight it (by for example introducing friendly bacteria/spores. Like kim chi or blue cheese) but the only way to hold off mold/bacteria indefinitely is to hermetically seal the container and then kill everything inside (canning. In which case the food only goes bad when it chemically dissolves).
It’s already there! It’s also all over your kitchen, but it takes a while to get to grow enough to be at dangerous levels.
Fun fact: the microbes that are responsible for making food mushy and gross and smelly are usually not the same microbes that can get you sick. However, they all grow well in similar conditions, so rotten-looking food is usually a good indicator that it also has the toxic stuff in it, too. Evolution taught us that they go hand in hand, so we learned to be repulsed by rotten food.
I make sourdough and beer as a hobby, from a decade before the pandemic, I feel compelled to add 🙂 and most of these comments are pretty close: mold is everywhere. They aren’t mentioning the most key part though.
When you make a sourdough starter people say you “capture the cultures from the air” but by and large that’s not really right. For one thing this seems like it would create huge differences in the flavor and activity level of the culture, but making a sourdough starter feels more consistent than this – you almost always end up with bread yeast instead of black mold or Shiitake mushrooms or what have you.
That’s because you’re not capturing the culture from the air, you’re reactivating spores *in the flour*. Think about it, what’s going to be better at eating flour than the yeast growing on the wheat? It’s still there after being ground into flour, and it’s this yeast you’re hydrating and waking up.
This is also why sourdough starter is more consistent in the cultures it grows than baked bread: you killed the innate culture with baking and now you really do have a good nutrition source for any old mold to find.
The mold is very frequently *already on the food* before you even buy it or try to store it, so a hermetically clean environment isn’t going to help. You’d have to like irradiate all your incoming food to prevent it from spoiling. And it’s not a big deal to eat these yeasts and bacteria anyway so long as you don’t eat too many of them, so we just try to slow them down instead of eliminating them.
I’m actually a mold remediation specialist, my background is in treating mold that grows in homes and businesses, but I can certainly shed some light here.
The simple answer is exactly what you have surmised: There are mold spores in every bit of air you have ever breathed. Thousands of spores in fact.
When we do mold remediation in a building, we have air sample testing done after the work to ensure we have treated all the mold. On these tests, we look to see if the mold levels indoors are equal to or lower than the mold levels outdoors at the time of testing. So even after we have professionally removed mold from a building, there are still thousands of mold spores floating in the air. And that’s because there are thousands of mold mores in every liter of air outside.
Mold needs three things to grow: A spore, an organic surface, and moisture. There are mold spores literally everywhere, food is an organic surface, and most food already has enough moisture to support mold growth. This is why almost all food, if exposed to air for a period of time, will grow mold.
It gets in because almost nothing in your fridge is perfectly sealed. You’re right, the mold spores are just everywhere. The spores themselves aren’t usually hazardous to humans, but when mold gets to grow for a while, their waste products will build up in whatever they’re growing in, which may be hazardous, but even then not always. Some molds or bacteria alter the flavor of food in a way humans like, and some alter the flavor quite negatively, but doesn’t really cause any severe health effects. However, it’s quite hard to tell what sort of mold species it is you’ve got growing on your food, so maybe you shouldn’t take unnecessary chances.
Refrigeration slows it down because low temperature means chemical and biological reactions slow down. Low temperature means less energy is available, and less energy available means things can’t grow as fast because there’s not enough energy to do the things the cells want to do as fast as they want to do it.
If you want an example of something that *doesn’t* get moldy, look no further than canned foods. These are actually perfectly sealed, and heat treated in such a way that anything that might have been inside the can before it was sealed is killed. No living things inside, no way of living things to get in, and you practically have infinite shelf life as long as the seal isn’t broken.
Mold, yeast, bacteria, and the rest are everywhere, on every surface, and in the air, all the time, forever. And they always win, eventually. Antimicrobial ingredients and refrigeration just delay the inevitable. Luckily our digestive systems are built to handle it to a point, and anything worse than that our other senses have evolved to keep us from eating that moldy bread. A good system, except for when we trick it with things like blue cheese.
Yep, Mold spores are everywhere, they are on your food too and can grow wherever they have moisture and food.
Latest Answers