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Fish and seafood from India

Pit-cured fish (Tamil Nadu)

Pit curing buries salted fish in mat-lined pits dug in the sand, where they ripen with little air for a few days to two weeks or more. The fish are then sold partly dried, without washing or further drying. A 1958 study at Mandapam found a 2- to 3-day cure gave the best flavour, with soft, deep-red flesh.

Fully documentedFish and seafood2 days – 28 days

Recipe

Amounts from a sourceThe experimental cure of Rao, Nayar and Valsan 1958 at Mandapam.
Indian mackerel (Rastrelliger kanagurta), about 20 cm longWashed, split along the back, gutted and the gills removed[rao1958]
Salt1 part salt to 5 parts fishLocal practice uses 1:5 or 1:6 for large fish and as little as 1:16 for small fish[rao1958]
Palmyra matsThe salted fish are bundled in mats before burial[rao1958]

Total time across the recorded steps: 2 days – 28 days

Start
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Close-up: salt moving into a fish

What changes: Split mackerel are rubbed with salt and folded into mat bundles

Step 1 of 4
Split, gut and salt the fish on mats
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
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

Pit curing buries salted fish in mat-lined pits dug in the sand, where they ripen with little air for a few days to two weeks or more. The fish are then sold partly dried, without washing or further drying. A 1958 study at Mandapam found a 2- to 3-day cure gave the best flavour, with soft, deep-red flesh. Made in 4 steps over 2 days – 28 days. The longest step, ripen in the pit, takes 2–28 days (Rao S.V.S 1958). Salt is 6.6 % → 10.2 % (Rao S.V.S 1958).

Key numbers
Main step2–28 daysReported[rao1958]Ripen in the pit
Salt6.6 % → 10.2 %Measured[rao1958]Ripen in the pit

What makes this one different

Pit curing ripens salted fish under sand with little air, unlike wet salting in open stacks. In the study the flesh softened and amino acid nitrogen more than doubled, while wet-salted fish stayed tough.

Related ferments

Safety

Pit-cured fish spoiled fast in storage. Total volatile base nitrogen passed 500 mg N % in about 2 weeks and reached 803.9–994.5 by the fourth week, against 551.8 after 9 weeks for wet-salted fish. Market samples often looked unwholesome and carried maggots (Rao et al. 1958). This is a record of a trade cure, not a home method. The study did not test for histamine or botulinum. The FDA ties histamine illness to scombroid fish (family Scombridae, which includes the mackerels), says it can form during salting, drying and fermenting, and says cooking or freezing cannot remove it. Fish buried with little air and kept unrefrigerated is closest to the FDA's unrefrigerated reduced-oxygen products. For those, its botulism controls are at least 20 % salt in the water phase of the flesh, pH 4.6 or below, or water activity 0.85 or below; its 5 % salt figure is for refrigerated products only. The study's 3-day fish reached about 14 % (computed from 10.2 % salt and 62.37 % moisture), and local practice went as low as 1 part salt to 16 of fish.

History and sources

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

Rao and colleagues (1958) cite earlier records of the cure. A 1916 fishery statistics report (Govindan) described moving the fish to fresh pits after the first day at some Tanjore villages, and a 1948 progress report (John) gave cures of up to four weeks in Travancore. Market samples were analysed in 1952 (Velankar) and 1956 (Krishna Pillai and colleagues). Rao and colleagues then studied the cure at Mandapam, where it was one of the main methods. A related sand-buried cure, pattarai karuvadu of Rameswaram (fish salted with turmeric and buried in sand for ten days in summer and 13 to 15 days in other seasons), was described in a 2024 news feature, which says the maker credits fishermen with finding by chance that salt in the sand kept buried fish fresh, and that an application for a geographical indication has been filed.

Starter
The sources we found do not say how its fermentation begins.
Microbes
No study we found names its microbes.
  1. [fda-ch7] US Food and Drug Administration, Fish and Fishery Products Hazards and Controls Guidance, Chapter 7: Scombrotoxin (Histamine) Formationgov
  2. [fda-ch13] US Food and Drug Administration, Fish and Fishery Products Hazards and Controls Guidance, Chapter 13: Clostridium botulinum Toxin Formationgov
  3. [rao1958] Rao S.V.S., Nayar M.R., Valsan A.P. 1958, Preliminary investigations on the pit curing of fish in India, Indian Journal of Fisheries (Central Marine Fisheries Research Station, Mandapam Camp)paper
  4. [narzary2021] Narzary Y., Das S., Goyal A.K., Lam S.S., Sarma H., Sharma D. 2021, Fermented fish products in South and Southeast Asian cuisine, Journal of Ethnic Foods 8:33, doi 10.1186/s42779-021-00109-0paper
  5. [foodtechnews2024] Food Tech News 2024, Pattarai Karuvadu - Rameswaram's exclusive dry fish craft poised for Geographical Indication tag (news feature on a related sand-buried fish cure)web