‘Fermented’ Potatoes

by lydia on April 18, 2013

I’m excited to share this post with you today about ‘fermented’ potatoes. I learned about the concept many years ago when I worked at an Outback Steakhouse. They go through great lengths, believe it or not, to prepare their potatoes. And as I can recall, it was the best-baked potato I ever had in a restaurant hands down. What was their secret? Soaking them in salt water.

Ever since last summer I’ve been making sure to soak or essentially ‘ferment’ my potatoes when I prepare them. It really is rather simple, especially if you menu plan or plan ahead. The benefit to this method is described below by my good friend Lisa Herndon, author of; ‘Lisa’s Counter Culture: Pickles & Other Well Bred Foods.‘ My favorite benefit is that this process lowers the starch content immensely. This is good news for anyone concerned about spiking their blood sugar. It thrills me too because I can allow my boys to enjoy their potatoes – it helps fill their bellies AND stretch the budget. I serve potatoes 2-3 times per week in my house. I’ll make Rosemary Roasted Potato Wedges and breakfast home fries most often. I’ve also got a great Potato Salad recipe using this method, try my Probiotic Rich, Purple & White Fingerling Potato Salad recipe here!

Potatoes in brine in the Pickl-It

‘Fermented’ Potato and Sweet Potato

I often think of potatoes and sweet potatoes as comfort food. Alas, I can’t seem to tolerate them without spiking my blood sugar for hours or experiencing bloating soon after eating them. This makes me sad. So I stopped eating them or did so rarely since I prefer feeling well.But there are times when a girl just needs some good ole taters. Since I am obsessed with fermenting, and already ferment almost anything, I decided to look into how traditional cultures prepared tubers. And it turns out that past generations were pretty clever. They usually soaked and fermented grains, vegetables, starches, etc…not only as a way of preserving them but also since it made them easier to digest. Voila! Thus the journey to soak and ferment potatoes began.

The upside of soaking and fermenting at the same time is that the starches/sugars that are released are now food for the beneficial bacteria and yeast to eat. So now you have these powerful probiotics working to neutralize anti-nutrients, make the nutrients (vitamins and minerals) more bioavailable and lend a little tang to your dish all with this easy step. Another benefit of soaking potatoes is the reduction or almost elimination of acrylamide. Acrylamide, is a chemical formed when foods high in starch are fried or cooked at high heat, such as baking or roasting. This is known as the Maillard reaction and is what lends the brown color and a specific flavor to roasted, fried and baked foods. Acrylamides may contribute to cancer in animals and may have health risks for people. And another huge plus is that it’s almost impossible to burn your taters after you ferment them. This is a great gift to some of us who may on occasion get distracted while cooking. Using a true anaerobic vessel to ferment your potatoes or sweet potatoes provides the ideal environment for the health promoting lactic acid bacteria to break down the starches and sugars. This method will lead to decrease acrylamides by 84%. If you want to essentially eliminate (98%) them, than use the Caldwell’s broad-spectrum starter. ( Caldwell’s vegetable starter is the only one available that is made from organic veggies).

Note that using whey or the Body Ecology starter (a narrow-spectrum starter—similar to what is used by the food industry based in dairy bacteria) are less than 50%. I’m including a recipe for fermented fries, but you can also ferment potatoes to be used for mashed, roasted quarters, or for making pancakes. Be creative! Keep in mind that the more surface area that is exposed, the higher amount of starch can be released. You can ferment whole potatoes but I recommend making sticks or chopping them into quarters. I find that digestive wise, red potatoes, yams and sweet potatoes tend to be the best options for those with sensitive guts or blood sugar regulation issues. And of course, I always recommend serving these with lots of good fat (duck fat, lard, ghee or coconut oil are all good options).  [Written by: Lisa Herndon of Lisa’s Counter Culture].

Sources:Science Daily: Limiting Harmful Acrylamide: Lactic Acid Bacteria to Lower Risk of Cancer Journal of the Science of Food and Agriculture: The Effects of Low-Temperature Potato Storage and Washing and Soaking Pre-Treatments on the Acrylamide Content of French Fries ScienceDaily: Soaking Potatoes In Water Before Frying Reduces Acrylamide

'Fermented' Potatoes
Recipe type: Side Dish
  • Potatoes (sweet, red or yams)
  • Salt (I prefer Himalayan)
  • Filtered Water Fat (bacon, ghee, coconut oil or ghee)
  • Caldwell starter (optional)
  1. Cut potatoes into thick or thin fries (or slice/quarter).
  2. Add this to the Pickl-it with a 3.5% salt brine. Close the lid and add water to the airlock.
  3. Caldwell starter: Each Caldwell packet is adequate for 4.5 pounds of food.
  4. For 3 pounds of potatoes, use ½ a packet in a 3.5% brine. Dissolve the starter in some water, and then add to the brine.
  5. Ferment for 24 to 48 hours away from direct light. A shorter ferment time is needed as more surface area of the potato is exposed (shredded will be much shorter than whole potatoes). Drain your potatoes.
  6. Toss the potatoes with your favorite fat (bacon grease, duck, lard or coconut oil) and favorite herbs and/or spices.
  7. Bake at 350°F for 35-45 minutes, depending on the thickness of your potatoes.
  8. Brine info:
  9. For a 1-liter vessel, use 35 grams of salt.
  10. For a 1.5-liter vessel, use 53 grams of salt.
  11. For a 2-liter vessel, use 70 grams of salt
  12. For a 3-liter vessel, use 105 grams of salt.
  13. For a 4-liter vessel, use 140 grams of salt.
  14. If you are using a fine grind salt like Himalayan pink salt, it is approximately 5 grams of salt per teaspoon.

If you are interested in more great info and recipes like this, pick up a copy of  ‘Lisa’s Counter Culture: Pickles and Other Well Bred Foods‘. The recipe for mayo in my potato salad was used from her book (with permission), and I learned how to soak my potatoes with the instructions found within as well. I am so glad to have this book as a resource as I navigate my way through finding recipes that work to ferment anaerobically, as well as having tips/guidelines to follow while I revamp my old recipes and create new ones. I can’t say enough good things about this ebook! Click here to visit LisasCounterCulture and purchase your copy today!



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Edie April 19, 2013 at 8:03 am

Can one ferment the potatoes for longer than 48 hr; like for a week??

lydia April 19, 2013 at 9:44 am

I would not recommend it – the potatoes will start to break down too much and lose their texture. Plus the liquid may start to smell. 48 hours is the most I’d do it for.

Edie April 19, 2013 at 8:04 am

Sorry, also, what if I don’t have a Pickle-it jar??

lydia April 19, 2013 at 9:47 am

It should be done anaerobically – many people do ferment things with mason jars, however you should know that if you soak in a mason jar – you are not really fermenting – just soaking – some lab activity may occur but some bad stuff can start growing too. I’d invest in an anaerobic vessel for your fermentation needs.

Brigitte March 8, 2016 at 2:43 pm

I teach fermenting. You can absolutely ferment in a Mason type jar, just make sure to keep all spices and pieces of veg under the brine , with a weight. There are several methods to achieve this. Different cultures use different methods. Don’t let not having ”the proper vessel” stop you. However, fermenting sweet potatoes may not be the easiest introduction to fermenting. Krauts, kimchis, carrots….all those are really good choices for a first time ferment.

JJ June 12, 2013 at 9:22 am

Can you give the exact break down of what makes up 3-5% salt brine if using a 1 litre Jar. Thanks

lydia December 5, 2013 at 6:50 pm


I’ve edited the recipe to reflect the break down of the 3.5% brine based on the size of your vessel.

Kim Douglas December 5, 2013 at 10:29 pm

Thank you for taking the time to give us a “recipe” for the brine. Awesome!

monica July 16, 2013 at 5:01 pm

Hi Lydia,
I did for 48 hour and the liquid smells foul. Are the potatoes safe to eat or deydrate?
Thanks in advance.

lydia July 17, 2013 at 10:59 am


How do you define foul? They should smell a little sourish…perhaps rinse them and than smell? They should be fine for cooking….I wouldn’t recommend dehydrating them in this case.

Kim Douglas November 26, 2013 at 11:34 am

I would like to try fermenting potatoes and I am also wondering with JJ above how to come up with a 3.5% salt solution, preferably not in metric measures. Also, I hope if anyone uses bacon grease, they are using bacon cured without nitrates/nitrites and all the other junk found in store bought bacon. :) Thank you

lydia December 5, 2013 at 6:51 pm


Yes, optimal bacon fat is assumed 😉

I edited the recipe so you can easily figure out the brine solution now.

Pogonia December 5, 2013 at 6:03 pm

Following to find out about the brine %age.

lydia December 5, 2013 at 6:51 pm


The recipe has been edited…..

Catherine January 29, 2014 at 11:29 am

I think you need to recheck you brine ratios. I get 69 grams of salt for 2 quarts of water using the brine calculator on the pickl it website. Am I not understanding this or what?

lydia April 10, 2014 at 12:54 pm

Well, our ratios are only 1 gram off from each other…….

kimyo July 21, 2015 at 10:06 pm

i think catherine is right about the salt ratio – pickl-it’s calc gives me 51 grams instead of 105.

perhaps the issue is that a 3 liter jar, filled with 2.5 pounds or so of potatoes, requires only 1.5 quarts of brine. 3 liters of brine @ 3.5% requires 105 grams of salt, yes. but to make 1.5 quarts you only need 51 grams.

in any case, thanks for the recipe and the tips.

Lisa April 10, 2014 at 12:37 pm

Lydia, I made a 1 gal jar full of fermented small white potatoes. I cut them into chunks a little larger than french fries. I fermented them for about 4 and 1/2 days.
I took some potatoes out of the brine and rinsed them off then cooked them in butter.
It took a very long time for them to cook and even when they were browned they still had an uncooked texture. The flavor was good without any additional seasoning. My brine was made with kefir whey as a starter and a little salt.
Why did they remain so hard, should I have used another type of potato or not fermented them as long?

Brenda July 20, 2014 at 3:18 pm

Can I reuse the brine and culture liquid for a second set of potatoes?

Anonymous March 15, 2015 at 3:27 pm

Is it possible to continue re-using the soaking medium for future batches to save on salt usage?

lydia March 16, 2015 at 4:00 pm

I would not recommend it – there will be starch residues in the water.

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