Ugba (also called ukpaka) is the Igbo name for fermented slices of the African oil bean, the seed of the Pentaclethra macrophylla tree, made across south-eastern Nigeria. The long-boiled, thinly sliced seeds are wrapped in leaves and left to ferment into pale, pungent, savoury strips. After 2–5 days ugba is eaten as a salad – most famously in abacha, the cassava-strip salad – and fermented for 6–10 days it becomes a flavouring for soups (Olasupo et al., 2016).
Why the Seeds Need So Much Work
Raw African oil beans aren’t edible: they contain saponins, an alkaloid called paucine, glycosides and other anti-nutritional or toxic factors. The traditional process deals with them in stages (Olasupo et al., 2016):
- Long boiling – reported anywhere from 5–8 hours to 16–18 hours – until the hard seed coats can be removed.
- Dehulling and slicing the cotyledons (the seed halves) into thin strips, then cooking them again.
- Soaking overnight and washing in water. In the authors’ own analysis this was the step that removed most of the tannins, saponins and alkaloids; fermentation removed more.
- Draining and wrapping the slices in leaves – typically small packets of 40–50 g – and leaving them to ferment for about 72 hours at room temperature.
What Ferments It
Ugba is an alkaline ferment, like dawadawa or natto: Bacillus bacteria break the seed proteins down into amino acids and ammonia, which is where the strong smell comes from, and the pH rises towards 8 instead of falling. That means ugba lacks the acid that protects sauerkraut or yogurt (Olasupo et al., 2016).
The Bacillus involved isn’t always benign. In ugba from several areas of south-eastern Nigeria, 42 of 49 bacterial isolates were Bacillus cereus, a food-poisoning species; all of them carried genes for diarrhoeal toxins, and one produced toxin during fermentation of the beans (Ahaotu et al., 2013). Researchers have tested defined starters instead: Bacillus subtilis and B. licheniformis together fermented ugba that matched the traditional product in 48 hours rather than 72 (Okorie & Olasupo, 2013).
Keeping It
Fresh ugba doesn’t last: in the same study it lost its colour, taste, texture and aroma after about 72 hours, while ugba dried at 50°C kept for six months at room temperature (Okorie & Olasupo, 2013). Keep fresh ugba in the fridge and use it within a couple of days, or dry it.
How It’s Eaten
Abacha: soaked dried cassava strips mixed with ugba, palm oil, ground crayfish, onion, chilli and sliced garden egg (African aubergine), often with fresh greens. Ugba also goes into soups and pepper soup. For other West African fermented seasonings, see ogiri.