E337 – Potassium sodium tartrate | Rochelle salt uses and safety

Quick analysis summary about E337 – Potassium sodium tartrate food additive

Bottom line about E337

E337 is potassium sodium tartrate, also called Rochelle salt. It is graded GREEN – SAFE because evidence does not show a credible concern at permitted food-use levels.

Why this grade for E337

Long-term L(+)-tartrate evidence is reassuring, direct bacterial testing of E337 was negative, and EFSA exposure estimates remained below its group intake limit.

Who may want to limit or avoid E337

Most people do not need to avoid E337, although unusually high tartrate intake can have laxative gastrointestinal effects.

Common uses and where E337 appears

E337 may be used as a stabiliser, sequestrant, emulsifier, or pH-control agent in selected foods including cheese products, processed fruit, confectionery, and other regulated categories.

E337 source or origin

Commercial E337 is commonly produced from wine-industry tartrate materials and then purified and crystallised, although manufacturing routes can vary.

Intake note for E337

EFSA set a group ADI (Acceptable Daily Intake) of 240 mg/kg body weight per day, expressed as tartaric acid, while JECFA retains a more conservative group ADI of 0–30 mg/kg body weight per day.

Is E337 banned anywhere?

E337 is authorised in the EU and permitted for food use in the US. Japan has treated potassium sodium tartrate as an undesignated additive in import enforcement, which is a non-approval status rather than a toxicity ban.

Safety grading GREEN – SAFE

At permitted food-use levels, the total evidence supports low risk. Modern long-term studies directly on E337 are sparse and dedicated reproductive-toxicity studies are unavailable, so the grade reflects reassuring overall evidence rather than complete additive-specific testing.

Study basis or key toxicological reasoning for E337

In a 104-week rat dietary study, monosodium L(+)-tartrate caused no treatment-related clinical, blood, urine, organ, histopathological, or tumour effects at the highest tested level [1]. EFSA later used the top dose as a NOAEL (No Observed Adverse Effect Level) of about 3,100 mg/kg body weight per day, with no LOAEL (Lowest Observed Adverse Effect Level) identified. This is indirect evidence because the study tested another L(+)-tartrate salt rather than E337 itself.

Direct E337 evidence is thinner. Potassium sodium tartrate was negative in bacterial mutagenicity tests up to 10 mg/plate, although the study had methodological limitations [2]. In a seven-day rat comparison at 2.73 g/kg body weight per day, DL-tartrate accumulated in kidneys and caused nephrotoxicity, while naturally occurring L(+)-tartrate did not show the same retention or toxicity [3]. Human and rat metabolism research also found important species differences in tartrate handling, supporting caution when extrapolating rat systemic exposure directly to humans [4].

Side effects of E337 – Potassium sodium tartrate food additive

Normal food use: No consistent adverse-effect pattern has been established at normal permitted food-additive exposure.
Gastrointestinal effects at high intake: A small human crossover study using cream of tartar found softer stools and shorter intestinal transit, but this was gram-level exposure to another tartrate source and is indirect evidence for E337 [5].
Kidney findings at extreme doses: Historical renal toxicity is linked mainly to DL-tartrate at very high experimental doses rather than the authorised L(+)-tartrate form [3].
Allergy or intolerance: A recurring E337-specific allergy pattern has not been established, but dedicated hypersensitivity evidence is sparse.

Should You Avoid E337 – Potassium sodium tartrate food additive?

Most people do not need to avoid foods solely because they contain E337 within permitted conditions. Toxicology is broadly reassuring, while the strongest adverse findings involve different tartrate stereoisomers or exposures far above normal food use. Concentrated tartrate salts and laxative-scale doses are not equivalent to ordinary food-additive exposure. Dedicated reproductive-toxicity data are missing, but the reviewed evidence does not identify a specific pregnancy or fertility hazard at normal dietary exposure.

Common uses of E337 – Potassium sodium tartrate food additive

Cheese and cheese products: It can function as an emulsifier or pH-control agent in permitted formulations.
Jams, jellies, and fruit preparations: It may help control acidity or support product stability where permitted.
Confectionery and chewing gum: EU rules allow tartrates in selected confectionery categories subject to applicable limits.
Processed fruit and vegetables: It may be used in specified categories under numerical EU maximum levels.
Fat and oil emulsions: Tartrates may be used in certain regulated emulsified products.
Other selected processed foods: Permissions vary by jurisdiction and food category, so legal authorisation does not mean E337 is routinely present in every listed food type.

Common names and synonyms of E337 – Potassium sodium tartrate food additive

Potassium sodium L(+)-tartrate
Sodium potassium tartrate
Rochelle salt
Seignette salt
Potassium sodium dextro-tartrate

What is E337 – Potassium sodium tartrate food additive?

E337 is the mixed potassium and sodium salt of naturally occurring L(+)-tartaric acid. The EU-authorised material is a water-soluble crystalline tetrahydrate. It can regulate acidity, sequester metal ions, stabilise formulations, and support emulsification.

Commercial potassium sodium tartrate is closely associated with wine production. Tartrate-rich materials such as tartar, wine lees, or grape residues can be neutralised, purified, concentrated, and crystallised into food-grade salt. This origin does not determine safety by itself.

The L(+)-configuration matters toxicologically. Experimental work shows that DL-tartrate can behave differently in the kidney from naturally occurring L(+)-tartrate [3]. A broader nutritional review discusses tartrate among dietary organic anions with differing metabolism [6]. Evidence from other tartrate forms therefore must be labelled as indirect rather than automatically transferred to E337.

Where is E337 – Potassium sodium tartrate food additive allowed (EU vs US)?

In the EU, E337 remains authorised, with current rules placing E334–337 and E354 in the tartaric acid–tartrates group and applying category-specific maximum levels from 16 December 2024. In the US, sodium potassium tartrate is affirmed as GRAS (Generally Recognized as Safe) for direct food use under good manufacturing practice as an emulsifier and pH-control agent. Exact permissions and maximum levels depend on the food category and jurisdiction.

E337 – Potassium sodium tartrate