Fermented Ketchup

Homemade ketchup is full of flavour and low in sugar

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5 from 1 review

Homemade ketchup is surprisingly easy. All you have to do is pack the ingredients in a jar and let the fermentation do the work.  It’s got a ton of flavor and is healthier than store-bought ketchup.


Units Scale

In the ferment

  • 3 cups tomato paste
  • 1 onion, diced
  • 2 cloves garlic
  • 1 cup raw apple cider vinegar (see notes for alternatives)
  • 1/3 cup raw sugar
  • 1 cinnamon stick
  • 1 bay leaf
  • 1/2 tsp each of allspice berries, cloves, mustard seed, black pepper

After fermenting

  • 1 tsp salt, to taste
  • 1/2 cup of water, as needed


  1. Mix together the tomato paste, onion, and garlic in a blender or food processor. Pulse until fully pureed. 
  2. Add the apple cider vinegar and sugar to the blender and pulse to blend. This will act as the culture for the ferment, so it needs to contain a mother. See notes for more details.
  3. Scrape the ketchup into a 1.5 L glass jar for fermenting (or use two 1-quart (1L) jars instead). Add in the whole spices. Cap with a loose-fitting lid.
  4. Place the jar in a cool and dark to ferment for 2 days (a kitchen cupboard is fine).
  5. After fermenting, stir in the salt. Add as much water as is needed to make a sauce-like consistency.
  6. Strain the ketchup through a fine-mesh sieve (affiliate link) to remove the spices. I usually bottle it at this point.
  7. Store the ketchup in fridge for up to 6 months. It will slowly continue to ferment, so you may need to add more sugar as it ages. Alternatively, you can freeze smaller portions of ketchup for future use.


  • The sugar is added to feed the ferment. If you don’t want any residual sugar after fermenting, reduce the sugar to 2 Tbsp.
  • It’s important to use raw apple cider vinegar (affiliate link). Look for “unpasteurized” or “with a mother” on the label. Alternatively, you could use acidic whey, unflavored kombucha, or other unflavored fermented beverages.