Ferment Potatoes
Timeframe: 3–5 Days
Fermenting potatoes before cooking is a way to help reduce glycoalkaloids and starches that may cause digestive discomfort or toxicity.
This traditional preparation method improves nutrient bioavailability and supports gut health—while making your potatoes easier to digest. I first learned about this from Dr. Bill Schindler, who did fascinating research on potatoes in Bolivia and Peru.
Why Ferment Potatoes?
Potatoes contain naturally occurring glycoalkaloids like solanine and chaconine, which can be toxic in higher amounts. These compounds are concentrated in the skin and just below the surface. Additionally, conventionally grown potatoes are heavily treated with:
Pesticides during cultivation
Sprout inhibitors post-harvest (like chlorpropham)
Fermentation and peeling both reduce toxic load, making potatoes safer and more nutritious to eat.
Ingredients & Supplies
Potatoes (preferably organic)
Non-iodized sea salt or kosher salt
Filtered water
Large mason jar or fermentation vessel
Kitchen scale (optional)
Instructions
1. Peel the Potatoes
Peel to remove pesticides, glycoalkaloid-rich skins, and sprout inhibitors. Compost or discard the peels. Important: discard any potatoes with green skins.
2. Slice into Uniform Pieces
Cut into wedges, sticks, or slices depending on how you plan to use them later (e.g., for fries or roasted potatoes).
3. Weigh Potatoes & Add Water
Place peeled potato slices into a large jar or fermentation vessel. Cover fully with filtered water. Use a kitchen scale to determine total weight of potatoes and water combined.
4. Add Salt (2% by weight)
Multiply the total weight by 0.02 (2%) to calculate how much salt to add. Stir well to dissolve salt into the water.
No scale? Use this approximation:
2 pounds of potatoes
Covered with water in a half-gallon jar
Add 40 grams of salt (about 2 tablespoons)
5. Ferment for 3–5 Days
Leave the jar at room temperature, loosely covered, for 3 to 5 days. You should see mild bubbling and slight cloudiness—signs of active fermentation.
6. Strain and Rinse
Once fermented, strain off the liquid and discard. Rinse potatoes under cool water. They’re now ready to cook or freeze for later use.
Potatoes fermenting in a jar to reduce toxins and improve digestibility.
Functional Nutrition Benefits
Reduces Glycoalkaloid Toxicity
Fermentation helps break down glycoalkaloids, compounds that can irritate the gut and nervous system when consumed in excess.
Lowers Pesticide & Chemical Load
Peeling removes surface residues, and fermentation may help reduce other contaminants, including sprout inhibitors.
Decreases Acrylamide Formation
Fermenting and soaking reduce excess starch, which in turn lowers acrylamide formation during high-heat cooking (acrylamide is a suspected carcinogen).
Improves Digestibility
Fermentation begins the breakdown of resistant starch and other complex carbohydrates, making potatoes easier to digest.
Lacto-Fermented French Fries Recipe
Once you’ve fermented and rinsed your potato slices, try turning them into crispy, nutrient-enhanced fries!
Once the potatoes are fermented, pat them dry before cooking to make superb fries.
Ingredients
Fermented potato slices
Healthy fat (olive oil, ghee, avocado oil, or beef tallow)
Sea salt
Optional spices: paprika, garlic powder, rosemary, cayenne
Instructions
Dry the potatoes
Pat slices dry with a clean kitchen towel or lay them out on a baking sheet to air dry or freeze.Preheat oven to 375°F
Line a baking sheet with parchment if desired.Bake (Phase 1)
Toss potatoes with a drizzle of healthy fat and season with salt and spices. Bake for 20 minutes.Crisp (Phase 2)
Increase oven to 425°F. Flip fries and bake another 20 minutes, or until golden and crispy.Serve with probiotic dips
Try homemade ranch dressing, a kefir cheese dip, or cultured sour cream with herbs.
Storage Tips
Fermented, uncooked potatoes can be frozen for later use after rinsing and drying.
Cooked fermented fries are best served fresh but can be reheated in the oven or air fryer.
Frequently Asked Questions
Q: Do fermented potatoes taste sour?
A: Mildly. The tang is subtle and usually not noticeable after cooking. The flavor is more savory and complex than raw potatoes.
Q: Can I ferment sweet potatoes?
A: You can! There’s an African recipe called Sweet Potato Fly that’s discussed in the book Wild Fermentation (affiliate link). Tip: use a food processor to grate the sweet potatoes — it takes forever by hand.
Q: Can fermentation fully detoxify potatoes?
A: Unclear. Fermentation likely reduces glycoalkaloids, and acrylamide precursors, but sourcing organic potatoes is still recommended. Definitely remove the skins. And be mindful of oxalates.
