Cultural Ferment

Borș Recipe: Romanian Fermented Wheat Bran for Souring Ciorbă

Borș is Romania’s centuries-old fermented wheat bran liquid — the secret souring agent behind authentic ciorbă soup. This complete guide covers the traditional fermentation method, how to activate and maintain a perpetual borș culture, the cherry leaf biopreservation technique, regional variations from Moldova to Transylvania, and classic Romanian soup recipes that depend on borș.

At a glance

Borș is a Romanian and Moldovan sour liquid made by fermenting scalded wheat bran in water for 2–4 days (1–2 days with some old borș as starter). Lactic acid bacteria – including starch-digesting Lactobacillus amylolyticus found in borș – sour it. It's used to sour ciorbă soups and boiled in them, so it's a flavouring rather than a probiotic. It isn't borscht.

  • Romanian/Moldovan sour liquid of fermented wheat bran, used to sour ciorbă soups.
  • Not the same as borscht, the beetroot soup.
  • Lactobacillus amylolyticus and L. oris have been isolated from borș.
  • Ready in 2–4 days; 1–2 days with old borș as a starter.
  • Boiled in the soup, so it adds sourness, not live cultures.

Ferment profile

Origin
Romania and Moldova
Fermentation
Lactic acid
Main microbes
Lactic acid bacteria (Lactobacillus amylolyticus, L. oris and others)
Live cultures
No (cooked, baked or pasteurized)
Alcohol
None / trace

Borș is a sour, cloudy liquid made by fermenting wheat bran in water for a few days. In Romania and Moldova it’s the traditional way to sour ciorbă – the family of sour soups that includes chicken, meatball (perișoare) and vegetable ciorbă – added near the end of cooking. Despite the similar name it isn’t borscht, the beetroot soup: borș is an ingredient, not a dish. It’s sold bottled in Romanian shops, and many households keep a batch going, using a little of the last one to start the next.

What Ferments It

Borș is a lactic ferment: bacteria living on the bran turn its starches and sugars into lactic acid, which gives the rounded sourness that distinguishes it from vinegar. Researchers in Bucharest who screened bacteria from Romanian fermented foods found starch-digesting Lactobacillus amylolyticus and L. oris in borș, and those strains produced bacteriocins – natural antibacterial proteins (Grosu-Tudor et al., 2014). The same group has used selected lactic acid bacteria to ferment wheat bran with beetroot or carrot into drinks (Zamfir et al., 2022).

Scalding the bran with boiling water at the start, as Romanian cooks do, gelatinises its starch so the bacteria can use it, and favours the heat-tolerant ones. Because borș is boiled in the soup, it’s a souring ingredient rather than a source of live cultures.

Using It

  • Ciorbă: add borș to the finished soup and bring it back to the boil for a few minutes; season with lovage or parsley and serve with sour cream. How much depends on the borș’s strength – start with about 500 ml per 3 litres of soup and taste.
  • No borș? Lemon juice, sauerkraut juice or a little vinegar will sour a ciorbă, with a sharper, less rounded taste.

For other sour grain ferments, see Polish żurek and Russian kvass; for how such cultures work, see our guide to the microbiology of sourdough.

Recipe: Homemade Borș

Makes
About 1.5 litres
Hands-on
15 min
Fermentation
2–4 days (1–2 with a starter)
Temperature
20–27°C (68–80°F)
Difficulty
Easy

Equipment

  • 2-litre glass or ceramic jar
  • Clean cloth
  • Sieve and fine cloth
  • Kettle or pot

Ingredients

  • 200 g wheat bran (plain, untoasted)
  • 2 tbsp cornmeal (optional)
  • 1.5–2 litres water
  • A slice rye or wholemeal bread, or 200–300 ml of old borș (as a starter)

Method

  1. Put the bran (and cornmeal) in the jar, pour over about 500 ml of boiling water, stir and leave for 10 minutes.
  2. Add the rest of the water, cold, so the mixture is lukewarm, and stir in the bread or old borș.
  3. Cover with a cloth and leave at 20–27°C, stirring once a day.
  4. From day 2, taste: it's ready when it's pleasantly sour, like diluted lemon juice – usually 2–4 days.
  5. Strain through a fine cloth, keep 200–300 ml (or some of the soaked bran) as the starter for next time, and refrigerate the rest. Use within about 2 weeks.
  6. Discard a batch that grows fuzzy or coloured mould, turns slimy, or smells rotten rather than sour.

Frequently asked questions

What is borș?

A sour liquid made by fermenting wheat bran in water, used in Romania and Moldova to sour ciorbă soups.

Is borș the same as borscht?

No. Borscht is a beetroot soup; borș is a fermented bran liquid used as an ingredient in sour soups.

How long does borș take to make?

About 2–4 days at room temperature for a first batch; 1–2 days when you add some old borș as a starter.

How long does borș keep?

About two weeks in the fridge; it slowly gets sourer.

What can I use instead of borș?

Lemon juice, sauerkraut juice or a little vinegar, though the sourness is sharper and less rounded.

Sources

  1. Grosu-Tudor SS et al. (2014). Characterization of some bacteriocins produced by lactic acid bacteria isolated from fermented foods. World J Microbiol Biotechnol 30(9):2459–2469. Link
  2. Zamfir M et al. (2022). Non-dairy fermented beverages produced with functional lactic acid bacteria. Microorganisms 10(12). Link
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