Tempoyak is fermented durian: ripe durian flesh mixed with a little salt and left in a closed container for several days until it turns sour and pungent. It’s made in Peninsular Malaysia, Sumatra and Kalimantan and used as a cooking ingredient rather than eaten on its own – most famously in masak lemak tempoyak, fish or prawns in a turmeric and coconut-milk gravy soured with tempoyak, and in sambal tempoyak.
What Turns Durian Sour
Durian flesh is rich in sugars, and lactic acid bacteria take over quickly. In tempoyak bought from Malaysian night markets, lactic acid bacteria reached 108.4–109.2 per gram and no other microbes came close; the sugars had dropped and lactic and acetic acid had risen. Strains of the Lactobacillus plantarum group dominated, alongside Lb. brevis, Leuconostoc mesenteroides and Lb. fermentum (Leisner et al., 2001).
A later study followed the fermentation over time: the fructose-loving Fructobacillus durionis – named after durian – and Leuconostoc mesenteroides led at first, and Lb. plantarum took over towards the end (Chuah et al., 2016). In tempoyak from Kalimantan, Indonesia, Lactobacillus made up about 90% of the bacteria (Murwani et al., 2024).
Temperature and Timing
Researchers at Universiti Putra Malaysia mixed durian pulp with 2% salt and held it at 15, 27 and 40°C for 10 days. At 15°C very little changed. At 27°C the pH and sugars fell, lactic and acetic acid rose, lactic acid bacteria peaked around day 3, and the aroma held up better than at 40°C; tempoyak fermented at 27°C was judged ready to eat between days 4 and 6 (Wasnin et al., 2014). That’s the basis for the recipe card below: 2% salt, warm room temperature, about 4–6 days, then the fridge.
Cook It
Tempoyak is acidic, but that doesn’t make it sterile. When researchers added food-poisoning bacteria to tempoyak, Listeria monocytogenes and Staphylococcus aureus survived for 8–12 days (Chuah et al., 2016). The traditional dishes simmer it, so use tempoyak cooked – in a curry, a fried sambal or a grilled marinade – and keep the jar in the fridge. Eaten cooked, it’s a flavoring rather than a source of live cultures.
Using Tempoyak
- Masak lemak tempoyak: fry pounded shallots, chilies and turmeric (or fresh turmeric leaf), add coconut milk and 2–3 tablespoons of tempoyak, then simmer fish, prawns or vegetables in it until cooked.
- Sambal tempoyak: fry chilies, shallots and anchovies or belacan, then stir in tempoyak and cook it through.
- Grilled fish: spread tempoyak and chili paste on fish, wrap in banana leaf and grill.
Frozen durian pulp works if fresh durian isn’t available. Other strongly flavored Southeast Asian ferments include fish sauce and tapai; for the basics of salt and lactic fermentation, see our troubleshooting guide.