How do I potato yeast?
April 12, 2020 12:04 PM   Subscribe

Recently, due to the dearth of baking yeast on any store shelf anywhere (not that I go out often to look) I followed the instructions using this recipe, for creating yeast from potatoes. Now, looking at the results, I am not sure I did it right. I don't want to attempt to make bread with it if I have to throw a mess out because it won't rise. Bakers of MeFi, please enlighten me.

I followed all the instructions - boiled the potatoes, removed the peel, added the sugar, water and salt to the mashed potatoes, and let it sit in a (covered) container for a few days, in an area averaging around 75 degrees. I did not use the potato water like other recipes call for, because this one didn't, and also the salt appears to be something the recipe could do without. Anyway, now it smells sour, as apparently it's supposed too, but there are hardly any bubbles. I put it in the fridge for a while, did some research, took it out again and let it sit uncovered. Still a sour smell, still hardly any bubbles. My questions are, one, did this actually become a usable yeast for bread and, two, how much do I use in bread, and how? I have a feeling if I just use "two tablespoons" nothing will happen. Obviously I could be completely wrong, but I've never made yeast like this before, and would prefer not to waste ingredients if I can avoid it.

Thank you!
posted by Crystal Fox to Food & Drink (7 answers total) 1 user marked this as a favorite
All this can possibly do is create a growing medium for random yeast that might wander into it while it’s sitting. Any yeast present on the potatoes to begin with will have been killed by the boiling. To have usable starter this way within a couple of days seems improbable.
posted by jon1270 at 12:54 PM on April 12, 2020 [3 favorites]

Tons of people have been frustrated by these articles popping up on the internet. You're not alone! :)

So, a few things here...

First, the whole "make your own yeast!" thing is complete bullcrap. All these instructions tend to provide are crappy instructions for making an immature sourdough culture. And make no mistake: That is what they are: sourdough cultures. This is not at all the same thing as making commercial yeast at home. Commercial yeast is not naturally occurring. The only way to get commercial yeast with all the characteristics we have some to expect is to purchase it.

Second, immature sourdough cultures are notoriously unstable and unpredictable in their ability to leaven, produce desirable flavors, etc. It is always much better, especially for novice sourdough bakers, to get a culture of known provenance with known characteristics. Contrary to popular belief, if a culture is fed and maintained properly it will retain its characteristics in any local environment. The gold standard for purchasing sourdough cultures is Sourdoughs International.

Third, there is no such thing as "potato yeast" unless you mean yeasts that live on potatoes and not in sourdough cultures. Any such yeast, however, would be killed by boiling the potatoes. All the potatoes (and sugar, etc.) do is provide a ready supply of simple sugars the will produce encouraging early fermentation from the activity of whatever microflora are around and make the novice baker feel better. These microflora do not do a very good job of leavening bread, and there is no way of knowing which ones you are getting anyway. More to the point, they are not adapted to living in a continually refreshed flour and water environment (a.k.a. a "sourdough starter") and will die off after a few refreshments to eventually be replaced by actual sourdough microflora. These sourdough microflora will then take some time to evolve into a stable symbiotic culture with known and desirable characteristics for sourdough baking. This is why there is usually a drop in activity after the initial flourishing in "recipes" of this kind. If you're dead set on creating your own sourdough culture, it's better to start off with just flour and water and skip all the other stuff. Be prepared for it to take some time and any number of unpredictable baking sessions before the starter becomes stable and you learn its quirks.

Fourth, sourdough baking is different from baking with commercial yeast and has peculiar challenges, not least among them that the acids produced by sourdough microflora degrade the gluten responsible for giving breads a lofty rise. As a result it's a bit of a balancing act to get a loaf with good flavor that isn't a brick.

Finally, there is still plenty of yeast to be found if you know where to look and how. Search for "SAF" or "Instaferm" yeast and you will find places selling 1 pound bags of high quality instant yeast for around 15 bucks. This stuff will last more or less forever in a jar in the freezer.
posted by slkinsey at 12:57 PM on April 12, 2020 [19 favorites]

Response by poster: Thank you, slkinsey. You confirmed what I already thought - this isn't a viable way to go. I might not have experience with "catching" a yeast, or whatever it's called, but what was going on in the jar just didn't seem right. I went ahead and ordered a commercial yeast. I'd seen the big bags before but was hesitant because I've always just purchased the little packets of Fleischmann's.

That said, I am curious as to how people made bread prior to the introduction of commercial yeast. Any good links or books anyone might suggest?
posted by Crystal Fox at 1:15 PM on April 12, 2020

Wild Yeast
If your house is too clean, this probably won’t work.
posted by Ideefixe at 1:24 PM on April 12, 2020 [1 favorite]

Would you like some Saf instant yeast? I paid a ridiculous amount ($30) for a pound when I couldn't find any in the stores, but I'm never going to go through it all and I'll happily mail you a ziplock bag with some. (I understand if you're reluctant to take yeast from a stranger in these, or any other, times, but just let me know if you want some).
posted by Fritzle at 7:32 AM on April 13, 2020

For reading on sourdough cultures and sourdough baking, Classic Sourdoughs : A Home Baker's Handbook, by Ed Wood (the proprietor of Sourdoughs International) is a good place to start. Unfortunately there is a lot of misinformation about sourdough around, and quite a bit of it has made its way into published books.
posted by slkinsey at 11:12 AM on April 15, 2020

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