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No yeast at home? Try culturing your own wild yeast on potatoes! All you need is one medium-sized potato, a bit of water and a smidge of patience.
Believe it or not, commercial yeast has only been available in well-stocked grocery stores for the past 100 years or so. Leavened bread, however, has been baked for millennia.
It’s convenient to be sure, but yeast packets are not the only way to leaven bread.
In times past, bakers cultured their own wild yeast for raising bread. Sourdough is one version, and it’s a community of yeast and lactic acid bacteria (like in yogurt) that give the bread a characteristic sour taste.
But what if you don’t like sourdough (or don’t have the patience to maintain one)?
There are literally dozens of ways to culture a wild yeast starter, using everything from raisins to beer to wild apples.
This simple method cultures wild yeast on boiled potatoes and was originally used by vodka distillers making high-quality potato vodka. The idea is to just culture yeast, without encouraging the lactic acid bacteria that are part of sourdough.
(If you’d rather just skip the potato yeast culture experiment and master homemade sourdough, I’d recommend The Art of Sourdough E-Course. It’ll take you through everything you need to know to bake high-quality sourdough bread without commercial yeast.)
DIY Potato Yeast Starter for Bread
Potatoes are high in starch, which is ideal for culturing yeast. They also contain plenty of micro-nutrients, making them a better yeast starter than sugar alone.
There are a number of different potato yeast starter recipes circulating on the internet at the moment, ever since yeast disappeared from store shelves this spring.
Guess what…they all work.
Some add sugar, others add a bit of flour and some are just a mashed potato and the starchy water used to boil it.
Mash it all together, and then leave it open on the counter for 2-3 days. Yeast floating by in the air will settle on your starchy yeast trap, and quickly go to work reproducing.
The simplest method, and the one originally used for vodka production, was just a single potato.
Peel the potato and place it in a pot of water. Bring the water to a boil, and then simmer for 35-45 minutes, until the potato is completely soft. Test it with a fork to ensure that it’s cooked and soft all the way to the center.
Pour the cooking water into a container, and allow it to cool. Meanwhile, thoroughly mash the potato.
Place the mashed potato into a one-quart mason jar, and then pour the starchy potato cooking water in to fill the jar. If you’re a bit short on cooking water, just add clean, chlorine-free drinking water.
Set the jar on the counter (open or covered with a towel), and wait.
In about 24 – 36 hours, you should see the first tiny bubble on the surface. (Look closely at the potato layer below, and you’ll see tiny bubbles forming there too.)
Cap up the jar, give it a vigorous shake to distribute the yeast and then open it up and leave the jar on the counter again.
In another 24 to 36 hours the jar should really be bubbling. At this point, you can bake your first loaf of bread (or wait another 2-3 days, your choice).
Alternate Potato Yeast Starters
The idea of culturing yeast on boiled potatoes isn’t just for emergencies or vodka bootleggers. Perhaps you’ve heard of Amish Friendship Bread? It’s a loaf of bread that’s like a chain letter that you pass onto unwitting friends.
Friendship bread starts with a home cultured starter, slow cultured over many days. After you bake the bread, a portion of the starter is passed on to friends with instructions so they can bake their own.
These days, a friendship bread starter is made with a few tablespoons of dried potato flakes and a pinch of storebought yeast.
Historically though, I doubt the Amish were buying instant mashed potatoes to make their starter. More likely the original recipe comes from a simple potato yeast starter, and these days potato flakes and yeast approximate the traditional (slower) method.
As I said, there are a number of variations for culturing yeast on potato starch, and they all work fine. Some are faster (the ones with sugar) and others are a bit slower, but they’ll all get you natural yeast for baking bread.
One method involves adding salt to the mix, which actually inhibits yeast a bit and selects for sourdough. That’s more properly a “potato sourdough starter” rather than a straight yeast starter.
To try that method, add 1 tsp salt and 1 tsp sugar to a quart jar containing potato water and a mashed potato. That said, it’s not one I’d suggest. If you want a sourdough culture, it’s much easier to just make a normal one with flour and water.
Another simple method adds both flour and sugar to the starter. This method has been shared on social channels like crazy, and yes, it does work:
Still, I chose to go with the simple potato method. Why? Because it’s the easiest to incorporate into existing bread recipes.
Baking with a Potato Yeast Starter
To use a potato yeast starter, simply pour off the starchy water at the top and use it in place of the water in your bread recipe. You can use it in any bread recipe, but know that wild cultured yeast will likely be a good bit less vigorous than commercially cultured yeast.
The ones they culture in labs take our impatience into account and raise the bread in just a few hours. Wild yeast, however, work on their own time table. Expect rise times to take 2-3 times longer with home cultured yeast, unless it happens to be very warm in your house.
Since we’re already working with potato, I’ve chosen to expand on the theme and make potato bread!
Most potato bread recipes actually only use the starchy potato water, rather than actual potatoes themselves. The resulting bread is soft and tender and makes an excellent sandwich loaf.
I happened to find a potato bread recipe from King Arthur Flour that uses both mashed potatoes and potato water. That allowed me to incorporate the cultured mashed potatoes at the bottom of the jar, and get more of the yeast culture into the final loaf.
Since the potatoes in the jar are soaking wet, I reduced the liquid in the recipe by 1/4 cup. I also doubled all the rise times.
Just look at the beautiful rise on that loaf…
Maintaining A Potato Yeast Starter
While you can just make a new potato yeast starter for each loaf of bread, it’s a lot simpler if you just maintain the culture.
To make my potato bread loaves, I started by pouring off 2 cups of the yeast/potato water to continue the culture and then used 1 cup potato water and 1 cup mashed potatoes from the bottom of the jar for the recipe.
The culture will need to be fed at this point, and the simplest way is to just boil another potato, mash it and allow it to cool completely. Add the yeast culture to the potato, and then top with cooled potato cooking water.
Alternately, if your bread recipe doesn’t use the mashed potato at the bottom of the jar, just add 1-2 tablespoons of sugar to the jar and fill with more water.
If you’re not planning on baking again in the next few days, store the starter in the refrigerator for later. The culture should last a few weeks in the refrigerator, just bring it back to room temperature before using it.
Troubleshooting
Like any new kitchen project, there are lots of ways this can go wrong.
The finished yeast starter should smell pleasant, very lightly of yeast, like rising bread. Possibly ever so slightly sour like sourdough, but mostly like yeast.
If your culture smells nasty….something went wrong.
Just like a home cultured sourdough starter, if the setup is wrong or it’s not tended, it’s always possible that you culture something besides yeast. To help ensure success, keep these things in mind:
- Make sure the container is open to the air, not capped. Yeast need surface area to land on, and you won’t be able to culture them in a closed container.
- Be sure to vigorously stir the jar (or briefly cap it to shake vigorously). This helps distribute the yeast and their food/substrate, and it also oxygenates the water which will help prevent anaerobic bacteria.
- Peel the potato. The peel will give off-flavors to the culture. Also, make sure it’s really thoroughly cooked through to the center before mashing.
- Use unchlorinated drinking water. Chlorinated tap water can prevent the yeast from culturing, but may not prevent other bacteria tolerant of low levels of chlorine.
- Once the culture is vigorously bubbling, put it in the refrigerator. If left on the counter for weeks on end, it will mold and spoil. Your goal is to catch the yeast, and then bake immediately, or push “pause” to hold the culture in a ready state in the fridge until you’re ready to use it.
Use your best judgment. As always, when in doubt, throw it out. Stay safe and don’t eat any food you believe may be spoiled.
If for some reason you just can’t get it to work, try a traditional sourdough starter (with flour and water).
(And If you do choose to go that route, I’d recommend The Art of Sourdough E-Course for sourdough beginners looking for great video tutorials covering every aspect of making sourdough bread.)
More Useful links for These Challenging Times
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Hi, thanks for this recipe! I started my potato 3 days ago, it smells really good, like bread, but there are no bubbles, should i wait longer or should i start over?
I would give it some more time. The first tiny bubbles don’t start to appear until 24-36 hours. As long as it smells good then you should be fine. The temperature of the house will make a difference too. The warmer it is, the faster it will work.
I made a potato starter and used it a few times. Well I left it in the counter for about a week and didn’t touch it. It now has a white film like a scoby almost on top. It smells yeast too like bread. Is it still useable? Do I keep the top layer and mix it back in? Can it be used to make another starter? I’ve googled this issue and can’t find anything but information on sourdough so I don’t know what to do.
If it looks like it has a layer on top, I would just skim that off and discard it. It’s probably just kahm yeast. Once you have scraped it off I would add 1 to 2 Tablespoons of sugar to feed it and see if it starts bubbling. Once it’s active again then you should be ok to use it or put it in the fridge if you won’t be using it for a while.
In how much water do you boil the potato?
You just need enough water when finished to fill a quart-sized jar after you have put the mashed potato in there. If you use 2 quarts, that should be more than enough. If not, you can always add a little non-chlorinated drinking water to top it off.
Do you need to warm up the potato water like you would normal water or would you kill the yeast?
There is no need to warm up the potato water. When you are using packaged yeast, the water is warmed to activate the yeast. In this case the yeast is already active.
Hi, just found your post in 2021…
Is there a certain temperature the room needs to be at, I started mine but the room cools off at night, it doesn’t stink, it just seems slow, just wondered if temperature needs to be consistent
Thanks
Standard room temperature is about perfect. If the temperatures are above that, it will work faster and below that will slow it down. You will get much better results with a consistently warm temperature.
Hi, I am very curious about this recipe. It sounds so good. But, I was wondering about the potato water combination.
Won’t the mashed potato absorb alot of the water? And when you take out the required amount of water,
won’t it have alot of the mashed potato mixed in with the water? I guess, I was just wondering if the liquid you
pour off is “sludgy” with the mixed potato, then how do you go about actually measuring the accurate amount
of potato?
Thanks
The potato lets off a lot of starch into the water. It shouldn’t be sludgy.
I dont understand how you covert this potato yeast to the recipe. The Potato Bread receipt from KA Flour says to use:
Ingredients
1 tablespoon instant yeast
1/2 cup (99g) sugar
1 1/4 to 1 1/2 cups (283g to 340g) lukewarm water or potato water (water in which potatoes have been boiled)*
3/4 cup (12 tablespoons, 170g) softened butter
2 1/2 teaspoons salt
2 large eggs
1 cup (198g) mashed potatoes (from about 1/2 pound potatoes)
6 1/2 cups (780g) King Arthur Unbleached All-Purpose Flour
What do you swap out from the above list of ingredients to use the “potato Yeast: I made?
Or do you need to add more cooked potatoes? I’m so confused!
Thanks, Toni
Hi Toni,
I was confused too until I realised that the King Arthur recipe used freshly boiled potatoes and their water.. When using the fermented potato water and potato you omit the instant yeast and use the same quantities stated in the recipe of fermented product.
Thanks for the wonderful knowledge. I have tried this twice and neither has worked for me. But still trying. The first batch looked good after two days then shock then in another 2 days it had pink mold on it. So tossed that one lol. The second one smell good after two days then shock it and decided to use it after another 24 hours. The liquid smelled fine but when I poured out the potatoes they smelled somewhat bad. Don’t know what I’m growing here in Florida lol. I did have the lid off all the time. I’ll keep trying.
I’m wondering, after you make the potato starter, can you continue to feed with instant potato flakes or do you need to continue to boil a potato and add the mashed up potato to the starter?
Congrats! I’ve made the yeast mix and am now preparing to bake my bread. Just letting you know that I’m sharing your link with a suburban Facebook group in Adelaide, Australia. We’ve come together to help each other since We’ve been told to stay home because of the Corona virus, and this looks perfect for a family activity while the kids are still stuck at home.
Would have loved to have been able to find a recipe for bread that just used the potato starter and not yeast as well. I’m going to try my own! Even looking on line, they all include yeast too!
I mention in the post that you can use the starter in yeast bread recipes by replacing the water in them with the potato starter.
Ok I made the starter with just the potato water. I never used the mashed potato. It looks like it’s separated. Can I add the mashed up potato later like the next morning or would you just start over.
Hello!
I made the yeast starter with potato water, flour and sugar. It’s been about 36 hours and my mix is very foamy and keeps rising.I kept it loosely covered with cling wrap during the night. I stir it every now and then to mix it up and keep it from rising too much. It doesn’t smell bad, but it smells like cheese and not yeast…I suppose it smells a bit like beer and cheese, lol, but not exactly like store bought yeast. Is that okay? Is it safe to use? Thanks for answering all these questions. 🙂
I honestly can’t say since I’m not there to look at it and smell it myself, you’ll have to use your best judgment. It sounds like it’s very active, which is great. Beer and cheese are both smells that sound good to me in this, as one is made with a yeast starter and the other I’d think would indicated lactobacillus culture which is a normal part of yogurt/sourdough (but I can’t know for sure obviously). If mine was active and smelled like beer/cheese I’d use it, but it’s your health and your kitchen, so you’ll have to make the decision for yourself.
Thank you very much! I went ahead and baked it up using that King Arthur Potato Bread recipe and it came out nicely! It’s a little dense and has a sourdough tang, but it was much softer than the sourdough I can buy at the store. I shared your blog with some friends, in case they’re feeling adventurous. 😉
Wonderful! I’m so glad it worked out for you =)
Can you use potato yeast in a bread maker?
I wouldn’t recommend it. Bread makers need a special rapid rise yeast that works faster than commercial yeast and at higher temperatures. Making bread with even regular yeast often doesn’t work in a bread maker, since most yeast isn’t meant to handle that quick rise time. You could get lucky I suppose, but more likely you’re going to catch a very slow rising yeast that needs 6-10 hours to raise a loaf. If you do try it, I’d suggest doing the knead in the bread maker and then allowing to it rise on its own for many hours. After that, put it in a pan and bake it in the oven when it’s risen enough.
Mine has been setting out for over 36 hours and I have no bubbles. Mashed up potato is in the the bottem and the water from boiling the potato is nearly clear. I used purified water to avoid chlorine and followed the above instructions. Would using the purified water cause it to not catch yeast? I shouldn’t think so but I am going to try again but have been raccking my brain to figure out where i have gone wrong.
Hi Ashley, this is quite fun! I feel like a pioneer woman making this! One question, i washed the potato but didn’t peel it. After 2 days everything looks and smells fine. Do you feel it’s ok that I didn’t peel it?
Yes, that should be fine!
Hi! I read somewhere that you should not use bleached flour for either sourdough or potato yEast starters. Would you agree? Thanks!
Honestly, I don’t know. I’ve never even seen bleached flour in the store. Everything they sell out here is unbleached, so I always assumed they didn’t even make bleached anymore. I guess I’m wrong and they still make it and sell it in some parts of the country?
Any recipes??? I did both the mashed potatoes and water in Mason jar and the flour, sugar and patotoe water over night starter. But not sure how apply them.
Just use the water from your starter as the water in a bread recipe. I included a link to a potato bread recipe from king Arthur flour that’s a good place to start, but you can really just pick any recipe and make whatever bread you want.
Mine turned into a pancake-batter looking mixture after I “shook it vigorously”. it did not stay separated with mashed potatoes at the bottom and water on top. It didn’t separate as it sat on the counter, either. Would you use the slurry in the same way you’ve advised using the potato water in the bread recipe?
Thank you so much for this detailed guide! It’s been a fun experiment to do at home with my boys. One question – my starter had a light layer of bubbles on day 2 but I wasn’t ready to bake it, so I left it for one more night. It’s got more bubbles now and doesn’t smell bad, but it doesn’t have the light yeasty smell that it did the day before (now it’s a bit sour?) and has some small slimy floaty additions (mucous-y texture). Is that normal?
Thank you!!
What is normal or not is a bit tricky here. A film on top is not normal for a yeast culture, so you’ve got something else growing there. It may be just the starch from the potato breaking down, or it may be something else. You’ll have to use your best judgment with it.
My starter bubbled up very nicely, but it smells like vomit. Should I throw the whole thing away?
If it smells nasty, then no good. You caught something else. Definitely toss it.
I’m so new at this…so when exactly do you place it in the fridge to maintain the starter? And what if you have some mashed potatoes left in your jar after using some in your first baking but don’t wish to continue to keep adding baked potatoes to feed and you just want to just feed with sugar instead? Will the mixture turn slightly slimy due to the breakdown of the potatoes left in the jar? Should I completely empty (strain) out the remaining potatoes and just keep the 2 cups of potato water to maintain and then add sugar to feed? Please advise…thank you!