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Vegetables from Southern Thailand

Look-kra-dorng (brine-pickled perah seeds)ลูกกระดอง

Look-kra-dorng is seeds of the perah tree, a southern Thai forest tree, mixed with about 10 % salt, covered with water and left under a thin cloth in the shade for about 5 days. They turn dark brown and taste salty, sour and slightly sweet. The raw seeds contain a compound that releases cyanide, a poison. Boil them first; no study we read shows that brine alone makes raw seeds safe to eat.

Fully documentedVegetables5 days

Recipe

Amounts from a sourceHome recipe from the JIRCAS card; salt is given as a share of the seed weight. The card's method lists no boiling, so the boiling step comes from a report on producers in Nopphitam district.
Perah seedsWashed, drained and then boiled, never raw (see the safety note)[jircas][ngamriabsakul2009][saengkrachang2020]
SaltAbout 10 % of the seed weight (w/w)[jircas]
WaterEnough to cover[jircas]

Total time across the recorded steps: 5 days

Start
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What changes: Starting material: perah seeds, washed and drained

Step 1 of 5
Wash and drain the seeds
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
Lactobacillus plantarum

The JIRCAS card starts here. Do not brine raw seeds.

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

Look-kra-dorng is seeds of the perah tree, a southern Thai forest tree, mixed with about 10 % salt, covered with water and left under a thin cloth in the shade for about 5 days. They turn dark brown and taste salty, sour and slightly sweet. The raw seeds contain a compound that releases cyanide, a poison. Boil them first; no study we read shows that brine alone makes raw seeds safe to eat. Made in 5 steps over 5 days. The longest step, cover with a thin cloth and ferment in the shade, takes 5 days (JIRCAS 2026). Salt is 10 % (JIRCAS 2026). Lactobacillus plantarum does most of the fermenting.

Key numbers
Main step5 daysReported[jircas]Cover with a thin cloth and ferment in the shade
Salt10 %Reported[jircas]Mix with salt and cover with water

What makes this one different

Look-kra-dorng is made from a forest seed rather than a leaf, stalk or bulb. In the south it is one of the local ways, with boiling and roasting, of processing the seeds before they are eaten [saengkrachang2020].

Related ferments

Safety

Perah seeds contain a cyanogenic glycoside, which releases the poison hydrogen cyanide and can kill, so southern Thai practice puts them through heating or pickling before they are eaten [saengkrachang2020]. Fresh seeds make people dizzy even in small amounts [ngamriabsakul2009]. Do not brine and eat raw seeds. No study we read shows that a brine alone makes them safe, and this page's recipe card does not say whether its seeds are cooked first. Producers in Nopphitam district, Nakhon Si Thammarat, boil or blanch the seeds for 10–20 minutes before salting, and the same report says local processing still lacks a safety standard [saengkrachang2020]. A preliminary study of Nakhon Si Thammarat seeds found 660 ppm of amygdalin in fresh seeds, 100 ppm after cooking and 25 ppm in cooked and fermented seeds; its abstract does not give the fermentation method, so it does not show what the JIRCAS brine removes [ngamriabsakul2009]. Boiling may not remove it all. Seeds boiled for 20 minutes at about 90 °C in salted, acidified water and then dried still held 47.79 mg total cyanide per kg dry weight, a product the authors judged safe [pichairat2025]. Results vary, since a Malaysian study found only traces in fresh and fermented seeds [husin2013].

Hazards the sources name: Amygdalin, a cyanide-releasing glycoside, at 660 ppm in fresh Nakhon Si Thammarat seeds, 100 ppm after cooking and 25 ppm in cooked and fermented seeds.

History and sources

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

Saengkrachang and colleagues (2020) describe the pra forest at Ban Thap Nam Tao in Nopphitam district, Nakhon Si Thammarat, which villagers keep standing. When the pods split, the villagers hold a ceremony to open the forest, and then gather the seeds. The report, citing Mompiboon and colleagues, says raw seeds sold wholesale for 50 to 100 baht a kilogram (prices vary with the season), while seeds boiled and pickled in brine, which keep for several months, sold for 100 to 150 baht. It presents processing as a way to earn more from the seeds than selling them raw [saengkrachang2020].

Starter
The sources we found do not say how its fermentation begins.
  1. [jircas] JIRCAS, Database of Fermented Foods of Thailand, Look-kra-dorng (brine pickled perah seeds) card, read 2026-10-23. Its microbe list cites The traditional fermented foods of Thailand (ASEAN, 1995).gov
  2. [mompiboon2018] Mompiboon P., Kaewsuwan W., Tripatch A., Wattananavin T. 2018, Development of food processing technology from pra seed (Elateriospermum tapos Blume) for commercial use, Wichcha Journal Nakhon Si Thammarat Rajabhat University 37 (special issue, June–August):114–128paper
  3. [ngamriabsakul2009] Ngamriabsakul C. and Kommen H. 2009, The preliminary detection of cyanogenic glycosides in Pra (Elateriospermum tapos Blume) by HPLC, Walailak Journal of Science and Technology 6(1):141–147 (abstract)paper
  4. [pichairat2025] Pichairat D. and Mahae N. 2025, Effects of boiling and drying conditions on the quality of Pra seed (Elateriospermun tapos Blume), Recent Science and Technology 17(3):262711 (abstract)paper
  5. [husin2013] Husin N., Tan N.A.H., Muhamad I.I. and Nawi N.M. 2013, Physicochemical and biochemical characteristics of the underutilized Elateriospermum tapos, Jurnal Teknologi 64(2), doi:10.11113/jt.v64.2045 (abstract)paper
  6. [saengkrachang2020] วราศรี แสงกระจ่าง, จุรีภรณ์ นวนมุสิก, จันทิรา วงศ์วิเชียร และพวงเพ็ญ บุญปก 2020, องค์ประกอบทางโภชนาการ และการจัดการวัตถุดิบต้นน้ำของเมล็ดประสดให้เหมาะสมต่อการแปรรูปเป็นผลิตภัณฑ์อาหารมูลค่าเพิ่มในพื้นที่อำเภอนบพิตำ จังหวัดนครศรีธรรมราช (Nutrition and upstream handling of fresh pra seeds in Nopphitam district, final research report), Nakhon Si Thammarat Rajabhat University, contract 07/2562paper