What even is yeast? I am thinking mainly of the kind we use to make bread rise. Which I buy from the grocery store…
But, back in the day, where did people find yeast? I assume people cultivate it and grow it, much like sour dough, but someone had to find it originally, right?
And what does ir do in the wild? Especially since it is so easy to kill? (Can’t be too hot, can’t touch salt, can’t be too old…)
Note: this is purely to do with my curiosity. I have no interest in actually hunting wild yeast
In: Biology
Yeast is literally everywhere. Like, you could probably make a sour dough starter from a skin swap if you really wanted to. You know that grey powder on grapes? that’s yeast. Sour dough starter is just yeast, that’s really really comfortable in a goop of flour and water. It’s just single celled fungi, that eat sugar and fart out CO2. Some of them also take other stuff and form aromatic compounds to get to the sugar. Those aromatic compounds are what makes wine or bread taste more complex than grape juice and oat meal.
“Yeast” is an incredibly diverse group of single-celled organisms that are broadly considered a type of fungus.
Some of them are colony forming.
Certain specific *kinds* of yeast have been used by humans for a variety of food-related things. We take advantage of their propensity for eating starches and sugars and producing carbon dioxide, acidity, and alcohol as a byproduct. In bread, we want the CO2 to help it rise. In beer and wine, we want the alcohol.
There are other organisms (like lactic acid producing bacteria in yogurt, cheese, sauerkraut, etc) that also fill similar food-preservation roles.
In the wild, yeast is everywhere, and it wakes up and eats whatever’s available when the conditions are right. The rest of the time it stays dormant (that’s why it comes from the store in those little dry pellets).
For a 5yr, i would read them Horton hears a who. Then i would get a packet of dry yeast and tell them each granule has as many individual yeasts as you have people in a whole town! Look with a magnifying glass.
Tell them microorganisms like yeasts are everywhere on earth, on your skin right now you have 1,000,000,000 microorganisms per sq cm. Its hard to imagine.
The harder part for a lot of people is the idea that these things can grow fast by multiplying. Both the multiplying and large number can be simulated by trying to make a million dots on a notebook. Tell them to start with 1, then 2,4,8. Tell them its kind of every hour you get this doubling. In yeasts it can be 1:100, but it takes longer (but that’s maybe too complicated). If you get to 100,000 that’s a lot. My kids school got together and did a million which went all along the wall in the hallway.
Finally explain that many microorganisms including yeast are good and necessary, like how they grow in your gut and help digest. Or how they keep dead things like trees from piling up to the sky. A few are mostly always bad maybe because they make things that irritate your body. And a few are around harmless but if you dont take care of them like by washing out a cut, or eating food that isnt stored properly, they will start to grow too much and we need medicine to get rid of them.
If you want to find some, just take a sugary liquid, like, say, apple juice… and leave it uncovered outside for a few days and when you come back to check on it it’ll be fermenting because wild yeast will have certainly found its way in there and started doing it’s thing. (it’ll probably have mold in it too, because other things besides yeast will get in there and compete for those resources)
I used to do a bit of homebrewing for fun, and while I never tried it myself, [there are lots of homebrewers that will try to capture and culture their own strains of wild yeast](https://bootlegbiology.com/diy/capturing-yeast/) to try to get unique flavors. It’s not a terribly difficult thing to do, just need some patience.
Also, yeast is a single-celled fungus that basically eats sugar and farts carbon dioxide and pees out alcohol. And it’s literally everywhere all the time. There’s some on you right now. [One brewer even used the yeast from his beard to make his beer. ](https://www.smithsonianmag.com/smart-news/brewmaster-makes-beer-from-his-beard-yeast-64843043/)
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