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Cereals and bread from India

Poita bhat (Assamese fermented rice)পইতা ভাত

Cooked rice is covered with water and left overnight, for about 12 to 16 hours, so that lactic acid bacteria such as Weissella confusa sour it slightly. The pH falls only to about 5.4, so it is a mild, short ferment.

Fully documentedCereals and bread12 h – 16 h

Recipe

Poita bhat (Assamese fermented rice), a photo from Wikimedia Commons
Photo: Tahmid Munaz from Dhaka, Bangladesh, CC BY-SA 2.0, via Wikimedia Commons
No fixed amounts recordedNo source read gives amounts; households simply cover leftover cooked rice with water.
Cooked rice[goswami2016][nath2021]
Water, to cover the rice[nath2021]
Starterspontaneous

Total time across the recorded steps: 12 h – 16 h

Start
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What changes: Rice is cooked before it is soaked

Step 1 of 4
Cook the rice
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Weissella confusa
Lactic acid bacteria

Both studies start from cooked rice. Output: cooked rice.

Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

Not documented for this step.

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Cooked rice is covered with water and left overnight, for about 12 to 16 hours, so that lactic acid bacteria such as Weissella confusa sour it slightly. The pH falls only to about 5.4, so it is a mild, short ferment. Made in 4 steps over 12 h – 16 h. The longest step, leave it overnight to sour, takes 12–16 h (Nath S 2021). Weissella confusa does most of the fermenting.

Key numbers
Main step12–16 hMeasured[nath2021][goswami2016]Leave it overnight to sour
AciditypH 6.8 → 5.39Measured[goswami2016]Leave it overnight to sour

What makes this one different

Poita bhat is a very short, mild ferment of rice that is already cooked, left one night under water. Panta bhat, eaten in Bangladesh and India, is made the same way, and Weissella confusa was found in both.

Related ferments

Safety

The rice is cooked before it is soaked. In one laboratory study of poita bhat the pH fell to about 5.4 in 12 h. In a study of panta bhat, the same kind of soaked cooked rice, from Bangladesh, the pH at 12 h was 5.81 at 20 °C and 4.86 at 30 °C. The FDA says Bacillus cereus grows from pH 4.9 to 9.3 and best at 28 to 35 °C, so the pH at 20 °C and in the laboratory study does not stop it. At 30 °C the pH was still 4.93 at 10 h, inside that range. The FDA says its vomiting toxin most often affects rice and other starchy foods, and that cooking may not disable the toxin. It advises keeping food at 40 °F (about 4 °C) or lower. The panta bhat study soaked the rice at 20 and 30 °C, well above that. No source we read tests this rice for B. cereus or gives a safe keeping time.

History and sources

Every number is labelled with how it is known. How this atlas is made

A traditional fermented rice of Assam. In 2016 Goswami and colleagues measured its pH, phytic acid and minerals over a 12 h fermentation. In 2021 Nath and colleagues sampled fermented sour rice from 23 households in Cachar district, Assam, and named Weissella confusa as the predominant fermenting bacterium.

  1. [goswami2016] Goswami G., Baruah H., Boro R.C., Barooah M. 2016, Fermentation reduces anti-nutritional content and increases mineral availability in Poita bhat, Asian Journal of Chemistry 28(9):1929–1932, doi:10.14233/ajchem.2016.19820 (abstract)paper
  2. [nath2021] Nath S., Roy M., Sikidar J., Deb B., Sharma I., Guha A. 2021, Characterization and in-vitro screening of probiotic potential of novel Weissella confusa strain GCC_19R1 isolated from fermented sour rice, Current Research in Biotechnology 3:99–108, doi:10.1016/j.crbiot.2021.04.001 (abstract, DOAJ record)paper
  3. [afrin2024] Afrin S., Orr C.H., Kuba S.Y., Naser S.R., Farooq R., Khan M.S., Menon M., Zanetti Domingues L., Sarker M.H. 2024, Microbiome profile and nutritional benefits of traditional overnight soaked cooked rice, Food and Humanity 3:100410, doi:10.1016/j.foohum.2024.100410 (table 1)paper
  4. [fda-bbb] US Food and Drug Administration 2012, Bad Bug Book, 2nd edition, Bacillus cereus and other Bacillus species (used for safety only)gov