Thiodipropionic acid

INS 388CAS 111-17-1

Listed as an antioxidant by Codex and the US.

Listed as antioxidants (US, Codex)
Chemical structure of Thiodipropionic acid, from PubChem compound 8096
Structure from PubChem CID 8096 (National Library of Medicine, public domain). A depiction of one compound: where a listing covers a family, or a substance has no single structure, this page shows none.

Thiodipropionic acid is an antioxidant used to protect fats and oils from rancidity.

Where it is and isn’t permitted

Status of Thiodipropionic acid by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
Australia and New ZealandFood Standards Australia New ZealandNo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
CanadaHealth CanadaNo listing matchedHealth Canada’s lists name additives without E or INS numbers, so this site matches them by exact name. A substance listed there under a name this site does not recognise has no row here.
European UnionEuropean Commission / EFSANo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
Great BritainFood Standards Agency / Food Standards ScotlandNo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
JapanConsumer Affairs AgencyNo listing matchedThis site imports only Japan’s list of designated additives (Appended Table 1 to the Regulations for Enforcement of the Food Sanitation Act), matched by English name. Existing additives, natural flavouring agents and ordinary foods used as additives are permitted outside that list and are not imported, so an empty row does not show that Japan does not permit the substance.
South KoreaMinistry of Food and Drug SafetyNo listing matchedThis site imports Part III of South Korea’s Standards and Specifications for Food Additives, matched by CAS number, then INS number, then exact name. Mixed preparations and sanitisers are not imported, and an entry whose identifiers disagreed with a page’s is held for review, so an empty row does not show that South Korea does not permit the substance.
United StatesFood and Drug AdministrationPermitted21 CFR 182.3109retrieved 2026-10-17
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

6 food categories

highest permitted level 1,000 mg/kg

Show every food category and its notes
  • 02.1.2 Vegetable oils and fats — 200 mg/kg
    • Note 46 As thiodipropionic acid.
    • Note 511 Excluding virgin and cold pressed oils in products conforming to the Standard for Edible Fats and Oils not Covered by Individual Standards (CXS 19-1981) and the Standard for Named Vegetable Oils (CXS 210-1999).
    • Note XS33 Excluding products conforming to the Standard for Olive Oils and Olive Pomace Oils (CODEX STAN 33-1981).
    • Note XS325R Excluding products conforming to the Regional Standard for Unrefined Shea Butter (CXS 325R-2017).
  • 02.1.3 Lard, tallow, fish oil, and other animal fats — 200 mg/kg
    • Note 46 As thiodipropionic acid.
    • Note XS211 Excluding products conforming to the Standard for Named Animal Fat (CODEX STAN 211-1999).
  • 02.2.2 Fat spreads, dairy fat spreads and blended spreads — 200 mg/kg
    • Note 46 As thiodipropionic acid.
    • Note XS253 Excluding products conforming to the Standard for Dairy Fat Spreads (CXS 253-2006).
  • 09.2.2 Frozen battered fish, fish fillets and fish products, including molluscs, crustaceans, and echinoderms — 200 mg/kg
    • Note 15 On the fat or oil basis.
    • Note 46 As thiodipropionic acid.
    • Note XS166 Excluding products conforming to the Standard for Quick Frozen Fish Sticks (Fish Fingers), Fish Portions and Fish Fillets – Breaded or in Batter (CODEX STAN 166-1989).
  • 14.1.4 Water-based flavoured drinks, including "sport," “energy,” or "electrolyte" drinks and particulated drinks — 1,000 mg/kg
    • Note 15 On the fat or oil basis.
    • Note 46 As thiodipropionic acid.
  • 15.0 Ready-to-eat savouries — 200 mg/kg
    • Note 46 As thiodipropionic acid.
CXS 192-1995 Table One, INS 388and 5 further provisionsretrieved 2026-09-07

How much is permitted

A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.

United States—1 no quantity stated
Codex Alimentarius200 mg/kg – 1,000 mg/kg6 numeric limit

What it is made from

Produced by chemical synthesis from acrylic acid and hydrogen sulfide.

  • Vegan
  • Vegetarian

Compare other additives on the dietary indexes.

CAS registry number
111-17-1
InChIKey
ODJQKYXPKWQWNK-UHFFFAOYSA-N
PubChem
CID 8096

How JECFA defines it

The international specification for identity and purity, prepared by the Joint FAO/WHO Expert Committee on Food Additives and published by FAO. It is a different document from any above, written by a different body and revised on its own cycle; it is advisory, and a country adopts it or does not.

INS 388 Thiodipropionic Acid

Synonyms: INS No. 388

Assay, identification and purity criteria

Description and assay

Specification history
Prepared at the 17th JECFA (1973), published in FNP 4 (1978) and in FNP 52 (1992). Metals and arsenic specifications revised at the 61st JECFA (2003). An ADI of 0-3 mg/kg bw was established at the 17th JECFA (1973)
Chemical names
3,3'-Thiodipropionic acid, diethyl sulfide 2,2'-dicarboxylic acid, thiodihydracrylic acid, ß,ß'-thiodipropionic acid
C.A.S. number
111-17-1
Chemical formula
C 6 H 10 O 4 S
Formula weight
178.21
Assay
Not less than 98.5%
DESCRIPTION
White crystalline solid having a slight characteristic odour
FUNCTIONAL USES
Antioxidant
METHOD OF ASSAY
Dissolve 0.350 g of the sample in 40 ml of water, add phenolphthalein TS and titrate with 0.1 N sodium hydroxide to the first appearance of a faint pink colour that persists for at least 30 sec. Each ml of 0.1 N sodium hydroxide is equivalent to 8.910 mg of C 6 H 10 O 4 S.

Identification

Solubility (Vol. 4)
Soluble in water; freely soluble in ethanol
Melting range (Vol. 4)
130 - 134 o
Sulfur
Between 17.5% and 18.5% See description under TESTS
Test: Sulfur
Weigh 0.700 g of the sample and add 100 ml of acetic acid and 50 ml of ethanol and heat the mixture gently until the sample dissolves completely. Add 3 ml of hydrochloric acid and add 4 drops of p-ethoxychrysoidin TS and immediately titrate with 0.1 N bromide-bromate TS. As the end point is approached (pink colour) add 4 more drops of the indicator solution and continue the titration dropwise, to a colour change from red to pale yellow. Perform a blank determination and make any necessary correction. Each ml of 0.1 N bromide-bromine TS is equivalent to 1.603 mg of S.

Purity criteria

Sulfated ash (Vol. 4)
Not more than 0.2%
Selenium (Vol. 4)
Not more than 30 mg/kg
Lead (Vol. 4)
Not more than 2 mg/kg Determine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, “Instrumental Methods.”

FAO JECFA Monograph 1 (2006)

Every name it appears under

55 recorded names. A label may use any of them.

E number

  • E388

INS number

  • 388

CAS registry number

  • 111-17-1

As it appears in regulation

  • Thiodipropionic acid

Other names

  • .beta.,.beta.'-Thiodipropionic acid
  • 3,3 inverted exclamation mark -Thiodipropionic Acid
  • 3,3 inverted exclamation mark(R)-Thiodipropionic acid
  • 3,3 inverted exclamation marka-Thiodipropionic acid
  • 3,3'-Sulfanediyldipropanoic acid
  • 3,3'-Thi
  • 3,3'-Thiobis(propanoic acid)
  • 3,3'-Thiobis-propanoic acid
  • 3,3'-Thiobispropanoic acid
  • 3,3'-Thiodi(propionic acid)
  • 3,3'-Thiodi-Propionic acid
  • 3,3'-Thiodipropanoic acid
  • 3,3'-Thiodipropionic acid
  • 3,3'-Thiodipropionic acid, 8CI
  • 3,3'-Thiodipropionic acid, 97%
  • 3,3'-thiodipropionic acid, 99%
  • 3,3-thiodipropionic acid
  • 3,3-Thiodipropionicacid
  • 3,3\'-Thiodipropionic acid
  • 3-(2-carboxyethylsulanyl)propanoic acid
  • 3-(2-carboxyethylsulfanyl)propanoic acid
  • 3-(2-carboxyethylthio)propanoic acid
  • 3-[(2-carboxyethyl)sulfanyl]propanoic acid
  • 3BBK323ED8
  • 4-Thiaheptanedioic acid
  • 4-Thiaheptanedioio acid
  • Bis(2-carboxyethyl) sulfide
  • CAS-111-17-1
  • CCRIS 3288
  • Diethyl sulfide 2,2'-dicarboxylic acid
  • Diethyl sulfide b,b'-dicarboxylic acid
  • Diethyl sulfide-2,2'-dicarboxylic acid
  • HSDB 858
  • InChI=1/C6H10O4S/c7-5(8)1-3-11-4-2-6(9)10/h1-4H2,(H,7,8)(H,9,10
  • INS NO.388
  • INS-388
  • Kyselina 3,3-thiodipropionova
  • Kyselina beta,beta'-thiodipropionova
  • Propanoic acid, 3,3'-thiobis-
  • Propanoic acid,3'-thiobis-
  • Propionic acid, 3,3'-thiodi-
  • Propionic acid,3'-thiodi-
  • Sulfide, bis(2-carboxyethyl)
  • TDPA
  • Thiahydracrylic acid
  • Thiobispropanoic acid
  • Thiodihydracrylic acid
  • THIODIPROPIONATES
  • THIODIPROPIONIC ACID
  • Tyox A
  • WLN: QV2S2VQ

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADI3 mg/kg bw/day—JECFA1973

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated rather than machine-read, and none has been written for this substance yet.

Common questions

Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.

What is INS 388?
INS 388 is Thiodipropionic acid. Thiodipropionic acid is an antioxidant used to protect fats and oils from rancidity.
What is Thiodipropionic acid used for in food?
It is listed as an antioxidant — the role Codex and the US assign it. This page shows every function each regulator records, with the citation for each.
Is Thiodipropionic acid banned in Europe?
No. Thiodipropionic acid does not appear on the EU's list of authorised food additives, which is not the same as being banned: the EU permits an additive only where it has authorised it, and usually the reason for an absence is that no one applied. The EU has made no finding against this substance. It does mean it may not be used as a food additive in the EU today.
Where is Thiodipropionic acid permitted?
Of the seven regulators this site reads, the US and the Codex standard permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Is Thiodipropionic acid vegan?
Yes. Thiodipropionic acid is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.

Sources for this page

  • ecfr retrieved 2026-10-17
  • gsfa retrieved 2026-09-07
  • jecfaspecs retrieved 2026-09-23

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable: a JSON record of this additive is given on request —how to ask for access.

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