Soibum is fermented bamboo shoot from Manipur in Northeast India: tender shoots, sliced thin and packed tightly to sour for weeks or months, until they’re pale, tangy and strongly aromatic. It’s used as an ingredient rather than eaten alone – in chutneys such as soibum iromba, with fish and pork, and in curries. Its relatives across the region include Manipur’s soidon (fermented shoot tips) and soijim, and mesu from the Sikkim Himalaya (Tamang et al., 2008).
What Ferments It
Like other vegetable ferments, fermented bamboo shoots are soured by lactic acid bacteria. In soibum, soidon, soijim and mesu, they reached up to 100 million per gram, mainly Lactobacillus brevis, Lactobacillus plantarum, Lactobacillus curvatus, Pediococcus pentosaceus, several Leuconostoc species and Enterococcus durans (Tamang et al., 2008). In natural soidon fermentations, the community shifted in three phases: Weissella and Lactococcus early on, Leuconostoc citreum joining by day 3, and L. brevis and L. plantarum taking over by days 5–7, after which it was stable (Romi et al., 2015). It’s the same succession that sours sauerkraut and kimchi.
Traditional soidon is made without salt, using a liquid starter from a previous batch called soidon mahi. When researchers tested those starters, 87% carried high counts of Bacillus cereus (a million or more per millilitre), which they flagged as a safety concern (Jeyaram et al., 2010). That’s one reason our home version below uses a weighed amount of salt and no back-slop starter, and why soibum is best eaten cooked.
Fresh Bamboo Shoots Must Be Cooked First
Raw bamboo shoots contain cyanogenic glycosides, natural compounds that release cyanide. Food Standards Australia New Zealand advises preparing fresh shoots by halving them lengthways, peeling off the outer leaves, trimming the fibrous tissue, slicing thinly and boiling in lightly salted water for 8–10 minutes, then discarding the water. Canned bamboo shoots have already been processed and are safe to use (FSANZ). The old version of this page recommended a 3–5 minute blanch; we now follow the FSANZ method. The same chemistry is why cassava needs careful processing – see our cassava staples guide.
Making It at Home
Outside Northeast India, fresh bamboo shoots turn up in Asian grocers in spring. Prepare them as above, then ferment them in a 2% salt brine like other vegetables; once sour, they keep in the fridge. Canned shoots, drained and rinsed, ferment too and are the simplest choice. Expect a strong, pungent smell – that’s normal for fermented bamboo – but fuzzy colored mold, sliminess or a rotten smell means discard. For other Himalayan ferments, see Nepal’s gundruk.