Where does yeast come from?

Can anybody tell me where yeast comes from? I mean the kind used in bread making, brewing, etc. I know what yeast is and what it does, I just want to know when Fleishmann’s puts the yeast in the jars, where do they get the yeast?

Since yeast is a living organism, it is grown. The web is full of pages on yeast growing, fermentation, etc.

Ummm, isn’t it cultivated? - they basically have a yeast source that has the properties they want, and they allow it to grow, taking some and drying it out and packaging it? I recognize there is more complexity to it than that, but isn’t that about it?

Lots of the yeast and bacteria used in food manufacture were originally human skin flora. Which makes sense, since humans would be around to infect the first prototypes of these products. The first yogurt happened when somebody accidently stuck his thumb in the milk and then forgetfully let it sit out for a few days. He was probably pretty hungry or he wouldn’t have tried to eat the stuff.

Many other products used wild yeast. The first alcoholic beverages were innoculated with airborne yeast spores. If you kept making the same beverage in the same place you’d tend to get the same yeasts. Eventually people figured out that the cloudy junk at the bottom of the wine or beer could be purposefully added to the malt/mash in order to get better quality control. I’ve made hard apple cider using wild yeast. In fact, if you use an old fashioned cider press it is almost impossible to prevent fermentation unless you pastuerize the juice.

But yeast cultures can give you more control over the product. Some yeast strains are more hardy and can withstand more alcohol before they die. If you use those you get a more potent beverage. Or maybe you want a sweeter beverage and use a different strain. If you use wild yeast you never know what you are going to get except through trial and error.

Bread yeast is the same. Wild yeasts would live in bakeries and the dough would get innoculated without anyone knowing why. Then someone figured out that they could save some old dough and purposefully innoculate the new dough. If you do this you can get much faster yeast growth, you can control the exact strain of yeast you use, and have more control over the bread you make.

Nowadays they grow yeast in big industrial vats then dry it out so it forms spores and sell it to consumers or food manufacturers. The only new step is intentionally drying and ensporulating the yeast so it can be stored longer.

I would add that one of my grandmother’s first jobs was working in the Fleischmann’s yeast factory in St. Louis around World War I. Unfortunately, she passed away earlier this year.

I do remember her stories of the factory. They were pretty gross. Worker safety wasn’t a priority. Not that people were getting mangled, but there were infections.