Is poi fermented? It can be both. Poi is cooked taro (kalo) pounded with water into a smooth paste. Freshly made, it’s mild and slightly sweet. Left at room temperature, lactic acid bacteria sour it over a day or more, and many people let it ferment on purpose – “sour poi”. Commercial poi is sold fresh and keeps souring in its bag, so the same poi can be eaten fresh or fermented depending on its age.
What Poi Is
Poi is a staple of traditional Hawaiian food, made only from taro corms and water. The cooked taro is pounded – traditionally with a stone pounder (pōhaku kuʻi ʻai) on a wooden board (papa kuʻi ʻai). The thick, undiluted paste is paʻiʻai; thinned with water, it becomes poi. Poi’s thickness is often described by how many fingers you need to scoop it: one-finger poi is thick, three-finger poi is thin.
Taro is also sacred in Hawaiian tradition. In the story of Hāloa, Wākea and Hoʻohōkūkalani’s first child was stillborn and buried, and the first taro plant grew from the spot. Their second son, named Hāloa after him, became the ancestor of the Hawaiian people – which makes taro humanity’s elder brother (University of Hawaiʻi at Hilo).
What Poi Tastes Like
- Fresh poi (the first day): smooth, slightly sticky, mild and faintly sweet and earthy – often compared to a very smooth, thin mashed potato.
- Sour poi (a few days old): tangy, a bit like plain yogurt, with a stronger, more complex aroma.
Researchers profiling commercial poi found that fresh and aged poi have clearly different aroma compounds, and that brands differ when fresh but become more alike as they ferment (Foster et al., 2025). Poi’s gray-purple color comes from the taro variety.
Poi is meant to be eaten alongside salty, rich foods – kālua pork, laulau, lomi salmon – which is why it can taste bland on its own.
What Happens When Poi Ferments
An early investigator found that the bacteria in poi were mostly Lactococcus lactis with some Lactobacillus, both lactic acid bacteria (Brown and Valiere, 2004). In a 2025 University of Hawaiʻi study, five commercial poi brands were fermented at 25°C (77°F) for 24 and 48 hours. Fermentation increased lactic acid bacteria such as Leuconostoc, Lactococcus, Weissella and Lactobacillus, and raised resistant starch and free amino acids, while the mineral content didn’t change (Stillwell et al., 2025).
Health evidence is limited. In the only controlled trial we found, 18 healthy adults ate fresh poi three times a day for four weeks; it didn’t change the bacteria measured in their stool or their bowel habits (Brown et al., 2005). Older reports suggested poi might help infants with allergies or failure to thrive, but reviewers called for more research (Brown and Valiere, 2004).
Poi Nutrition
| Per 100 g | Poi |
|---|---|
| Energy | 112 kcal |
| Carbohydrate | 27.2 g |
| Fiber | 0.4 g |
| Protein | 0.4 g |
| Fat | 0.1 g |
| Potassium | 183 mg |
| Sodium | 12 mg |
| Vitamin B6 | 0.27 mg |
From USDA FoodData Central (poi). Poi is almost all starch: low in fat, protein, fiber and sodium, with some potassium and vitamin B6. A cup (240 g) has about 270 kcal. It’s naturally gluten-free and dairy-free.
Tips for Making Poi
- Cook the taro completely. Raw or undercooked taro contains calcium oxalate crystals that make the mouth and throat itch and burn. Cook until a skewer slides through the center of every corm with no resistance.
- Handle raw taro with gloves if your skin is sensitive.
- Add water gradually while pounding or blending; you can always thin it more.
- Taste daily if fermenting. Refrigerate when it’s as sour as you like – it keeps souring slowly in the fridge.
- A thin layer of water on top of stored poi helps stop a dry crust forming; stir it in before eating.
How to Eat Poi
- With a traditional Hawaiian plate: kālua pork, laulau, lomi salmon, poke or chicken long rice.
- Sweetened with a little coconut milk, honey or fruit, as breakfast or dessert.
- Blended into smoothies in place of yogurt.
Other starchy staples that are fermented before eating include Ethiopian injera, South Indian idli and dosa, and West Africa’s fermented cassava staples. For children, see probiotic foods for kids by age. Pacific Islanders also fermented breadfruit in pits – see fermented breadfruit.