Thai script ส้มตำ. TCPS 1161/2549 defines the dressing as ground garlic and fresh chilli seasoned with sugar, fish sauce, nam pu, pla ra, salt, tamarind water, lime juice or citric acid, at a pH no higher than 4.5. The standard’s own labelling clause names both ส้มตำไทย and ส้มตำปลาร้า. No Thai standard defines the salad — no papaya, no proportions, no mortar. The document that matters most is the one for pla ra, TCPS 37/2557: at least 12 per cent salt, every preservative and synthetic colour banned, and zero liver fluke larvae permitted in a 100 gram sample. Its definition clause says pla ra should be cooked before eating.
What the Thai government says som tam dressing is
The Thai Industrial Standards Institute, part of the Ministry of Industry, publishes the Thai Community Product Standard series. Searching its register for ส้มตำ returns exactly one document: TCPS 1161/2549, น้ำปรุงส้มตำ, som tam seasoning liquid. It covers the bottled dressing, and its definition clause is the closest thing to an official ingredient list that exists for this dish.
| Ingredient | Thai | How the standard treats it |
|---|---|---|
| Garlic | กระเทียม | Base - washed clean, then ground fine |
| Fresh chilli | พริกสด | Base - washed clean, then ground fine |
| Sugar | น้ำตาล | Seasoning group |
| Fish sauce | น้ำปลา | Seasoning group |
| Nam pu | น้ำปู | Seasoning group - the boiled-down paddy crab liquid used in the north |
| Pla ra | ปลาร้า | Seasoning group - and the reason section 03 exists |
| Salt | เกลือ | Seasoning group |
| Tamarind water | น้ำมะขามเปียก | Seasoning group |
| Lime juice | น้ำมะนาว | Seasoning group |
| Citric acid | กรดซิทริก | Seasoning group - named in the standard alongside the natural acids |
Three entries repay attention. Pla ra sits inside the definition of the product, not in a footnote about variants. Nam pu — the boiled-down paddy crab liquid used in northern cooking — sits there beside it, in a standard most people would assume describes a central Thai dressing. And citric acid is named alongside tamarind and lime, which is the Ministry of Industry being realistic about how a shelf-stable bottle is acidified. The pH ceiling of 4.5 is what all three acids are there to achieve.
What the standard does not do is describe the salad. There is no papaya in it, no long bean, no tomato, no dried shrimp, no peanut, no mortar and no quantity of anything. If you want proportions, no official Thai document will give them to you, and we are not going to invent them.
ส้มตำไทย and ส้มตำปลาร้า are both in the labelling rule
Clause 6.1(1) of TCPS 1161/2549 tells a producer what the container may be called, and it gives two worked examples: น้ำปรุงส้มตำไทย and น้ำส้มตำปลาร้า. The distinction that gets explained badly in a thousand blog posts is, in Thailand, a labelling rule. The certificate register makes the same point from the other direction: of the three producers currently certified against this standard, the one in Bang Nam Priao district, Chachoengsao holds its certificate for a product named ready-made som tam pla ra seasoning liquid.
The other two current holders are an individual producer in Mueang Phitsanulok district, Phitsanulok, and a limited company in Nong Suea district, Pathum Thani. We name districts and provinces rather than people, because many certificate holders are private individuals whose home addresses and mobile numbers are published in the register. Certificates are issued by that province’s industry office and expire after three to five years.
The pla ra standard, which is the strict one
TCPS 37/2557, ปลาร้า — issued as TISI notification No. 1948 of 27 August 2557, replacing the 2546 version — defines pla ra as fish fermented with salt, with finely ground roasted rice, rice bran or roasted rice bran added in appropriate proportion before or after the salt fermentation. It recognises three types: whole fish, pieces, and ground. And the definition clause ends with an instruction rather than a description: ควรทำให้สุกก่อนบริโภค — should be cooked before eating. Clause 7.1 then requires that same instruction to be printed on the label, next to the Ministry of Public Health food serial number. Clause 5.1 requires the premises to hold a Ministry of Public Health licence.
| What the standard measures | The requirement |
|---|---|
| Salt (sodium chloride) | Not less than 12 per cent by weight - a floor, not a ceiling |
| Synthetic colours | All kinds prohibited |
| Preservatives | All kinds prohibited |
| Lead | Less than 1 mg/kg |
| Inorganic arsenic | Less than 2 mg/kg |
| Mercury | Less than 0.5 mg/kg |
| Cadmium | Less than 2 mg/kg |
| Salmonella | Not detected in a 25 g sample |
| Gnathostoma spinigerum | Not found in a 100 g sample |
| Opisthorchis viverrini metacercariae | Not found in a 100 g sample - the liver fluke, at zero tolerance |
Clause 4.10 is the one worth reading twice. Thai food standards do not usually contain a parasitology section. This one requires that no Gnathostoma spinigerum and no metacercariae of Opisthorchis viverrini be found in a 100 gram sample, tested by the method in the Compendium of Methods for the Microbiological Examination of Foods, fourth edition, 2001. Opisthorchis viverrini is the liver fluke. A government that writes a zero-tolerance parasite clause into a fermented fish specification is telling you plainly what the risk is.
Raw pla ra in the mortar, and what the Ministry of Public Health says
The Department of Disease Control’s warning of 4 November 2565 names ส้มตำปลาร้าดิบ — som tam made with raw pla ra — among the dishes that carry liver fluke risk. It states that squeezing lime does not kill the larvae and only changes the colour of the flesh; that sour seasonings such as lime and tamarind and salty ones such as fish sauce, salt and pla ra brine do not cook food; and that only heat does. It reports that the parasite can live in a person for up to 30 years and that chronic or repeated infection is a major cause of cholangiocarcinoma, cancer of the bile duct.
This is a sharper problem for som tam than for most dishes, because the whole preparation happens cold in a mortar. Nothing in the sequence applies heat. If the pla ra going in has been boiled down into a dressing first — and one current certificate holder, in Mueang Phitsanulok, is certified specifically for น้ำปลาร้าต้มสุก, cooked pla ra liquid — then it has been through heat. If it is spooned in raw, it has not. That is a fair thing to ask a cook, and asking it is normal.
We have set out the department’s warning in full, including the symptom progression and its four precepts of prevention, on our larb page, because it applies to a whole family of dishes rather than to this one. This page is not medical advice and BAANLYY is not a medical provider.
Nine standards carry the word ปลาร้า
Searching the register for ปลาร้า returns nine published standards, which is a measure of how much of the Thai kitchen is built on one ingredient: 37/2557 pla ra itself, 131/2566 pla ra chilli paste, 132/2556 pla ra bong, 133/2556 stir-fried chopped pla ra, 134/2557 pla ra powder, 135/2557 pla ra cube, 877/2563 dry-fried pla ra meat, 1346/2557 pla ra liquid and 1476/2557 pla ra som. Twelve current certificates sit across seven of them.
Where those twelve sit is worth stating plainly, because it is not what the reputation suggests: Nakhon Nayok, Chachoengsao, Nakhon Sawan, Phetchabun, Udon Thani, Khon Kaen, Phitsanulok, Pathum Thani and Saraburi — only two of the twelve in the northeast. Read that as a fact about certificates rather than about cooking. Seeking certification is a commercial decision made by people who sell a packaged product, and the register counts certificates, not kitchens. The source that does speak to geography is the Department of Disease Control, which reports liver fluke prevalence as highest in the northeast and the north.
What we could not confirm, and did not invent
- The salad. No Thai standard defines som tam as a dish. Green papaya is not named in any document we read, and neither are long bean, tomato, dried shrimp, peanut, palm sugar or the mortar. Everything above is about a bottled dressing and a fermented fish.
- The other named versions. ตำซั่ว, ตำปู and ตำถั่ว are real and widely sold. Only ส้มตำไทย and ส้มตำปลาร้า appear in an official document, and only as label examples, so the others are not described here.
- Where it came from. The papaya is not native to Southeast Asia and the dish is commonly attributed to Lao and northeastern Thai cooking. We could not confirm that against a primary source and no standard mentions it, so it is not stated as fact.
- Any heritage listing. The Department of Cultural Promotion’s intangible cultural heritage portal at ich.culture.go.th does not resolve, so we make no claim in either direction about registration.
- Whether certification is compulsory. We confirmed that certificates are issued to named producers by provincial industry offices and expire after three to five years. We found no official statement that any seller is obliged to hold one.
- Prices, and where to eat it. No official source for either, and we do not name restaurants we cannot verify.
Frequently asked questions
Thailand has published a definition. Thai Community Product Standard TCPS 1161/2549 defines som tam seasoning liquid as a product made by taking garlic and fresh chilli, washing them clean and grinding them fine, then seasoning with seasonings such as sugar, fish sauce, nam pu, pla ra, salt, tamarind water, lime juice and citric acid. Two things are worth noticing about that list. Pla ra - fermented fish - sits in the definition of the product itself, not as an optional extra somebody adds; so does nam pu, the boiled-down paddy crab liquid used in the north. And the acid can be tamarind, lime or citric acid, which is the standard acknowledging that a bottled dressing may be acidified rather than relying on fruit. The standard caps pH at 4.5 and requires the liquid to be free of things like lime pips and tamarind shell. It does not name papaya, long bean, tomato, peanut, dried shrimp or the mortar, because it is a standard for a bottled dressing and not for the salad.
The standard itself recognises both, which is more than most sources can say. TCPS 1161/2549's labelling clause 6.1(1) tells a producer what to call the product and gives two examples: น้ำปรุงส้มตำไทย, som tam thai seasoning liquid, and น้ำส้มตำปลาร้า, som tam pla ra liquid. So the split between a lime-and-fish-sauce dressing and a fermented-fish dressing is written into the government's own labelling rule rather than being restaurant shorthand. The certificate register bears it out: one of the three current holders of this standard, a community enterprise in Bang Nam Priao district, Chachoengsao, is certified for a product named ready-made som tam pla ra seasoning liquid. What no document we found does is define the boundary - how much pla ra makes a som tam pla ra, or what else changes with it. For that, ask the cook.
It depends entirely on whether it has been cooked, and Thailand says so in two separate documents. TCPS 37/2557, the standard for pla ra, puts the advice inside the definition clause: this is a product that should be cooked before eating. Its clause 7.1 then requires that instruction to appear on the label. And clause 4.10 sets a parasite requirement most people do not expect from a food standard: no Gnathostoma spinigerum and no metacercariae of Opisthorchis viverrini - the liver fluke - may be found in a 100 gram sample. That is zero tolerance, tested by a named laboratory method. Separately, the Department of Disease Control's warning of 4 November 2565 names som tam made with raw pla ra among the dishes that carry liver fluke risk, and states that neither sour seasonings such as lime and tamarind nor salty ones such as fish sauce, salt and pla ra brine cook food or kill the parasite - only heat does. The practical version: a pla ra dressing that has been boiled has been through heat; a spoonful of raw pla ra dropped into the mortar has not. It is a reasonable thing to ask about. This page is not medical advice and BAANLYY is not a medical provider. Our page on larb sets out the department's warning in full.
No. The Department of Disease Control singles that belief out and corrects it directly: squeezing lime does not destroy the larvae at all, and lime juice merely changes the colour of the flesh. The same warning extends the point to every seasoning a som tam contains - sour ones such as lime juice and tamarind, salty ones such as fish sauce, salt and pla ra brine - and states that none of them makes food cooked. Heat is the only method the department accepts. This matters more in a som tam than in most dishes, because the whole preparation happens cold in a mortar, and the visual cue people trust, flesh changing colour in acid, is precisely the cue the department says means nothing here.
At least 12 per cent salt by weight, and that is a legal floor rather than a typical figure. TCPS 37/2557 clause 4.6 requires sodium chloride of not less than 12 per cent by weight in a product that meets the standard. For context, that is the preservation mechanism doing its work: the same standard prohibits all preservatives and all synthetic colours outright, so salt, the fermentation, and the roasted rice or rice bran added before or after it are what the product has instead. The standard also caps heavy metals - lead below 1 milligram per kilogram, inorganic arsenic below 2, mercury below 0.5, cadmium below 2 - and recognises three physical types: whole fish, pieces, and ground. If you cook with pla ra, the salt floor is the number to hold in mind before you add fish sauce as well.
The honest answer is that the government's registers do not locate it where you would expect, and we would rather show you that than smooth it over. On 8 September 2026 the certificate register returned three current holders of the som tam seasoning standard: Mueang Phitsanulok district in Phitsanulok, Nong Suea district in Pathum Thani, and Bang Nam Priao district in Chachoengsao. Across all seven pla ra standards that have any holder, it returned twelve certificates spread over Nakhon Nayok, Chachoengsao, Nakhon Sawan, Phetchabun, Udon Thani, Khon Kaen, Phitsanulok, Pathum Thani and Saraburi - only two of the twelve in the northeast. That is not evidence that som tam and pla ra belong to the central plains. It is evidence about who has sought a certificate for a packaged product, which is a commercial decision, and the register counts certificates rather than cooks. The Department of Disease Control is the source that does speak about geography, and it reports liver fluke prevalence as highest in the northeast and the north - which tells you where the fermented-fish eating is concentrated, from a different direction entirely.
Related guides
- Larb — the full Department of Disease Control warning, its symptom progression and its four precepts of prevention.
- Khanom chin — the fermented rice noodle these dressings most often arrive on.
- Khao soi — the northern noodle bowl, and the curry powder written into its standard.
- Thai street food — how ordering actually works, including how to ask for less chilli.
- Thai regional food — how the four regional kitchens differ.
- Dining in Udon Thani — eating in the northeast, where the pla ra versions are the default.
- Cost of living in Khon Kaen — what the northeast costs, if the food is what started this.
- Health insurance in Thailand — because a stool test and a specialist referral are things worth being covered for.
The northeast is the cheapest part of Thailand to live in, and the best place to eat this
If som tam is what put Isan on your list, the next question is what a month there actually costs.
Sources & References
- Thai Industrial Standards Institute, Ministry of Industry - Thai Community Product Standard TCPS 1161/2549, Som Tam Seasoning Liquid. Its definition clause 2.1 describes a product made by taking garlic and fresh chilli, washed clean, and grinding them fine, then seasoning with seasonings such as sugar, fish sauce, nam pu, pla ra, salt, tamarind water, lime juice and citric acid. It requires an appropriately thick liquid free of unwanted parts of the ingredients such as lime pips and tamarind shell, caps pH at 4.5, and sets microbiological ceilings including Staphylococcus aureus at 100 colonies per gram and yeast and mould at 10 colonies per gram. Its labelling clause 6.1(1) gives two example product names: som tam thai seasoning liquid and som tam pla ra liquid
- Thai Industrial Standards Institute - Thai Community Product Standard TCPS 37/2557, Fermented Fish (Pla Ra). Its definition clause 2.1 describes fish fermented with salt, with finely ground roasted rice, rice bran or roasted rice bran added in appropriate proportion before or after the salt fermentation, and states in the definition itself that it should be cooked before eating. Clause 4.6 requires not less than 12 per cent salt by weight. Clause 4.8 prohibits all synthetic colours and all preservatives. Clause 4.10 requires that no Gnathostoma spinigerum and no metacercariae of Opisthorchis viverrini be found in a 100 gram sample. Clause 5.1 requires the premises to be licensed by the Ministry of Public Health, and clause 7.1 requires the label to carry consumption advice such as should be cooked before eating, together with the food serial number. Issued as TISI notification No. 1948 (B.E. 2557), decided at sub-committee meeting 27-1/2557 on 18 July 2557 and announced on 27 August 2557, replacing TCPS 37/2546
- Department of Disease Control, Ministry of Public Health - public warning of 4 November 2565 on eating white-scaled freshwater fish raw or lightly cooked, issued through the Risk Communication and Health Behaviour Development Division and citing the Director-General and a Deputy Director-General. It names som tam made with raw pla ra among the dishes that carry liver fluke risk, states that squeezing lime does not kill the larvae and only changes the colour of the flesh, states that sour seasonings such as lime and tamarind and salty ones such as fish sauce, salt and pla ra brine do not cook food, states that only heat kills the larvae, reports that the parasite can live in a person for up to 30 years, links chronic and repeated infection to cholangiocarcinoma, and reports prevalence as highest in the northeast and the north
- Thai Industrial Standards Institute - the public register of published community product standards, queried directly on 8 September 2026. Searching som tam returns exactly one standard, TCPS 1161/2549 for the seasoning liquid, and no standard for the salad itself. Searching pla ra returns nine: 37/2557 pla ra, 131/2566 pla ra chilli paste, 132/2556 pla ra bong, 133/2556 stir-fried chopped pla ra, 134/2557 pla ra powder, 135/2557 pla ra cube, 877/2563 dry-fried pla ra meat, 1346/2557 pla ra liquid and 1476/2557 pla ra som
- Thai Industrial Standards Institute - the public register of certified community producers, queried directly on 8 September 2026. Against TCPS 1161/2549 it returns three current certificate holders: an individual producer in Mueang Phitsanulok district, Phitsanulok; a limited company in Nong Suea district, Pathum Thani; and a community enterprise in Bang Nam Priao district, Chachoengsao, whose certified product is named ready-made som tam pla ra seasoning liquid. Across the seven pla ra standards that have any holder at all the register returns twelve current certificates, in Nakhon Nayok, Chachoengsao, Nakhon Sawan, Phetchabun, Udon Thani, Khon Kaen, Phitsanulok, Pathum Thani and Saraburi
Primary and official sources are cited above. Government rules, fees and procedures in Thailand change over time and vary by office; always confirm current requirements with the relevant authority before relying on them. BAANLYY never takes paid placement in editorial content.
