Aluminum potassium sulfate
10043-67-1 · 15007-61-1 · 7784-24-9 · 09OXB01F3O · Alaun · AlK(SO4)2 · Alum potassium · Alum, N.F. · Alum, potassium anhydrous · Alumen · Aluminium potassium bis(sulphate) · Aluminium potassium sulfate · aluminium potassium sulfate (1/1/2) · ALUMINIUM POTASSIUM SULFATE (1:1:2) · Aluminium potassium sulfate, anhydrous · Aluminium potassium sulphate · Aluminium potassium sulphate anhydrous · ALUMINIUM POTASSIUM-SULFATE DODECAHYDRATE · aluminium(3+) ion potassium disulfate · Aluminum potassium alum · Aluminum potassium disulfate · Aluminum potassium sulfate · ALUMINUM POTASSIUM SULFATE (1:1:2) · Aluminum Potassium Sulfate (1:1:2) Dodecahydrate · Aluminum potassium sulfate (AlK(SO4)2) · Aluminum potassium sulfate (KAl(SO4)2) · ALUMINUM POTASSIUM SULFATE, ACS · Aluminum potassium sulfate, alum · Aluminum potassium sulfate, anhydrous · Aluminum potassium sulfate, puriss., anhydrous, calcined, >=98% (calc with ref. to anhyd. subst.), powder · ALUMINUM POTASSIUM SULPHATE · ALUMINUM POTASSIUM SULPHATE (1:1:2) · ALUMINUM POTASSIUM SULPHATE ANHYDROUS · ALUMINUMPOTASSIUMSULFATE · Bestmade Natural Products Alum (Kali Alum Sulph) · CCRIS 6842 · Dialuminum dipotassium sulfate · E 522 · Exsiccated alum · HSDB 2685 · INS NO.522 · INS-522 · Kalinite · NHS CONSTIPATION · Potash alum · POTASH-ALUM · Potassium alum · Potassium alum anhydrous · Potassium Aluminium Sulfate · Potassium aluminum alum · potassium aluminum disulfate · Potassium aluminum sulfate · Potassium aluminum sulfate (1:1:2) · POTASSIUM-ALUM · POTASSIUM-ALUM- · Rxhomeo Homeopathic Combo · Sulfuric acid, aluminium potassium salt (2:1:1) · Sulfuric acid, aluminum potassium salt (2:1:1) · Tai-Ace K 150 · Tai-Ace K 20 · E522 · aluminum;potassium;disulfate · aluminum;potassium;disulfate;dodecahydrate · Aluminium potassium sulphate · Aluminum potassium sulfate · Aliuminio kalio sulfatas · Alumiinikaliumsulfaatti · Alumiiniumkaaliumsulfaat · Aluminij kalijev sulfat · ALUMINIJEV KALIJEV SULFAT · Aluminium potassium sulphate · Aluminiumkaliumsulfaat · Aluminiumkaliumsulfat · Alumínium-kálium-szulfát · Alumīnija kālija sulfāts · kalijev aluminijev sulfat · Siarczan glinowo-potasowy · Solfato di alluminio e potassio · Sulfat de aluminiu și potasiu · SULFAT TAL-ALUMINJU U TAL-POTASSJU · Sulfat tal-potassju tal-aluminju · Sulfate d’aluminium potassique · SULFATO DE ALUMINIO Y POTASIO · Sulfato de alumínio e potássio · Sulfato doble de aluminio y potasio · SÍRAN HLINITO-DRASELNÝ · Síran draselno-hlinitý · Síran hlinitodraselný · Θειϊκό αργιλιοκάλιο · Алуминиевокалиев сулфатE number E522CAS 10043-67-1
Listed as a firming agent by Canada and the US.
Listed as firming agents (CA, US) · acidity regulators (US) · raising agents (CA)
- Canada: Firming agent — Health Canada, List of Permitted Firming Agents (List 6)
- United States: Firming agent — FDA, Substances Added to Food: ALUMINUM POTASSIUM SULFATE
- United States: pH control agent — FDA, Substances Added to Food: ALUMINUM POTASSIUM SULFATE
- Canada: Acid-reacting material — Health Canada, List of Permitted Acidity Regulators and Acid-Reacting Materials (List 10)
Aluminium potassium sulfate, a form of alum, is a firming agent used in pickles and a component of some baking powders.
Where it is and isn’t permitted
| Jurisdiction | Status | Scope and limits | Citation |
|---|---|---|---|
| Australia and New Zealand | No 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. | ||
| Canada | Permitted, with conditions | highest permitted level 350 mg/kg 5 permitted uses Show every permitted use
| Health Canadaand 4 further provisionsretrieved 2026-10-17 |
| European Union | Permitted, with conditions | 1 food category Permitted as a member of Aluminium sulphates. Note 1: The additives may be added individually or in combination. | Regulation (EC) No 1333/2008, Annex II, as amended by (EU) No 380/2012, via Aluminium sulphatesretrieved 2026-10-18 |
| Great Britain | Permitted, with conditions | 1 food category highest permitted level 200 mg/kg or mg/l Permitted as a member of E 520–523: Aluminium sulphates. ML = 200. only candied cherries Period of application: from 1 February 2014. Note (1): The additives may be added individually or in combination. Note (38): Expressed as aluminium. | Assimilated Regulation (EC) No 1333/2008, Annex II (as at 28 June 2024), via E 520–523: Aluminium sulphatesretrieved 2026-10-18 |
| Japan | Permitted, with conditions | Designated additive: Appended Table 1, item 451, 硫酸アルミニウムカリウム（結晶物の場合にあつては別名ミョウバン又はカリミョウバン、乾燥物の場合にあつては別名焼ミョウバン） (“Aluminum Potassium Sulfate (Crystal: Alum or Potassium Alum, Dried: …Designated additive: Appended Table 1, item 451, 硫酸アルミニウムカリウム（結晶物の場合にあつては別名ミョウバン又はカリミョウバン、乾燥物の場合にあつては別名焼ミョウバン） (“Aluminum Potassium Sulfate (Crystal: Alum or Potassium Alum, Dried: Burnt Alum)” in the unofficial English translation). Standards for use — Specifications and Standards for Foods, Food Additives, etc. (MHW Notification No. 370 of 1959), Part II (Food Additives), F (Standards for use), entry 硫酸アルミニウムカリウム: (1) [must not be used in the foods stated] “硫酸アルミニウムカリウムは、みそに使用してはならない。” (2) [sets maximum levels of use for the foods stated] “硫酸アルミニウムカリウムの使用量は、アルミニウムとして、菓子、生菓子又はパンにあっては、その1kgにつき0.1g以下でなければならない。” The Japanese is the standard as published. There is no official English translation of the Notification; the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications for this additive, in the same Notification, are not imported and are not shown here; nor are the general rules in F 添加物一般, which apply to every additive. | Regulations for Enforcement of the Food Sanitation Act (MHW Ordinance No. 23 of 1948), Appended Table 1retrieved 2026-10-18 |
| South Korea | Permitted, with conditions | Designated food additive: Standards and Specifications for Food Additives, Part III, 1. …Designated food additive: Standards and Specifications for Food Additives, Part III, 1. 일반식품첨가물 (general food additives), 황산알루미늄칼륨 (“Aluminium Potassium Sulfate”, the English the Code prints beside it). Main use (주용도) of 황산알루미늄칼륨: 산도조절제, 팽창제, 안정제. Standard for use (사용기준) of 황산알루미늄칼륨: (1) [may be used only in the foods listed; sets a limit on the amount used] “황산알루미늄칼륨은 아래의 식품에 한하여 사용하여야 한다. 황산알루미늄칼륨의 사용량은 알루미늄으로서 1. 과자 및 이의 제조용 믹스, 빵류 및 이의 제조용 믹스, 튀김 제조용 믹스 : 0.1g/kg 이하(황산알루미늄암모늄, 산성알루미늄인산나트륨, 염기성알루미늄인산나트륨과 병용할 때에는 알루미늄의 합계가 0.1g/kg 이하) 2. 땅콩 또는 견과류 가공품(밤에 한함), 서류가공품(고구마에 한함), 기타 어육가공품, 과·채가공품 : 0.1g/kg 이하(황산알루미늄암모늄과 병용할 때에는 알루미늄의 합계가 0.1g/kg 이하) 3. 면류 및 이의 제조용 믹스, 기타 수산물가공품, 전분가공품, 만두피 : 0.2g/kg 이하(황산알루미늄암모늄과 병용할 때에는 알루미늄의 합계가 0.2g/kg 이하) 4. 절임식품 : 0.5g/kg 이하(황산알루미늄암모늄과 병용할 때에는 알루미늄의 합계가 0.5g/kg 이하)” The Korean is the standard as published. There is no official English translation of the current Code (the English version on MFDS’s website is the 2020 edition and has no legal effect); the English in square brackets is this site’s description of what each sentence does, not a translation of the foods or the levels. Compositional specifications (Part IV) are not imported, nor are the general standards in Part II, which apply to every additive. | Standards and Specifications for Food Additives (식품첨가물의 기준 및 규격), MFDS Notification, Part III (Standards for use, by item)retrieved 2026-10-18 |
| United States | Permitted | 21 CFR 182.1129retrieved 2026-10-17 | |
| Codex Alimentarius | Not listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited. |
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.
| Canada | 11 mg/kg – 35,000 mg/kg | 3 numeric limit, 1 GMP, 1 no quantity stated |
|---|---|---|
| European Union | — | 1 no quantity stated |
| Great Britain | 200 mg/kg | 1 numeric limit |
| Japan | — | 1 no quantity stated |
| South Korea | — | 1 no quantity stated |
| United States | — | 1 no quantity stated |
What it is made from
Crystallised from aluminium sulfate and potassium sulfate together.
- Vegan
- Vegetarian
Compare other additives on the dietary indexes.
- CAS registry number
- 10043-67-1
- InChIKey
- GRLPQNLYRHEGIJ-UHFFFAOYSA-J
- PubChem
- CID 24856
The two specifications, compared
The European Union sets identity and purity by regulation; JECFA publishes its own through FAO, advisory until a country adopts it. Both documents are below in full. These are the parameters each puts a number on.
| Parameter | European Union | JECFA |
|---|---|---|
| Assay | no less than 99.5 % | no less than 99.5 % |
| Lead | no more than 5 mg/kg | no more than 5 mg/kg |
| Arsenic | no more than 3 mg/kg | — |
| Mercury | no more than 1 mg/kg | — |
The two documents state the same figures for every parameter compared here.
How the EU defines it
The legal specification an additive must meet to be sold as this E number in the EU — what it is, how it may be made, and the purity it must reach. From Commission Regulation (EU) No 231/2012.
E 522 Aluminium potassium sulphate
Synonyms: Potassium alum; Potash alum
Assay, identification and purity criteria
Description and assay
- Einecs
- 233-141-3
- Chemical name
- Aluminium potassium sulphate dodecahydrate
- Chemical formula
- AlK(SO₄)₂ · 12 H₂O
- Molecular weight
- 474,38
- Assay
- Content not less than 99,5 %
- Description
- Large, transparent crystals or white crystalline powder
Identification
- Test for aluminium
- Passes test
- Test for potassium
- Passes test
- Test for sulphate
- Passes test
- pH
- Between 3,0 and 4,0 (10 % solution)
- Solubility
- Freely soluble in water, insoluble in ethanol
Purity criteria
- Ammonium salts
- No odour of ammonia detectable after heating
- Selenium
- Not more than 30 mg/kg
- Fluoride
- Not more than 30 mg/kg
- Arsenic
- Not more than 3 mg/kg
- Lead
- Not more than 5 mg/kg
- Mercury
- Not more than 1 mg/kg
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 522 Aluminium Potassium Sulfate
Synonyms: Potassium alum; potash alum; Burnt alum (anhydrous); INS No. 522
Assay, identification and purity criteria
Description and assay
- Specification history
- Prepared at the 55 th JECFA (2000) and published in the Combined Compendium of Food Additive Specifications, FAO JECFA Monographs 1 (2005). A PTWI of 2 mg/kg bw for aluminium was established at the 74 th JECFA (2011).
- Chemical names
- Aluminium potassium sulfate dodecahydrate Aluminium potassium sulfate anhydrous
- C.A.S. number
- 7784-24-9 (dodecahydrate) 10043-67-1 (anhydrous)
- Chemical formula
- AlK(SO4)2 · xH2O (x = 0 or 12)
- Formula weight
- 474.38 (dodecahydrate) 258.21 (anhydrous)
- Assay
- Dodecahydrate: not less than 99.5% Anhydrous form: not less than 96.5%
- DESCRIPTION
- Large, transparent crystals or crystalline fragments, or white crystalline powder; odourless
- FUNCTIONAL USES
- Acidity regulator, firming agent, raising agent
- METHOD OF ASSAY
- a) Dodecahydrate form Weigh accurately about 1 g of the sample, dissolve in 50 ml of water, add 50.0 ml of 0.05 M disodium ethylenediamine-tetraacetate, and boil gently for 5 min. Cool, and with continuous stirring add in the order given: 20 ml of pH 4.5 buffer solution (77.1 g of ammonium acetate and 57 ml of glacial acetic acid in 1000 ml), 50 ml of ethanol, and 2 ml of dithizone TS. Titrate with 0.05 M zinc sulfate to a bright rose-pink colour, and perform a blank determination. Each ml of 0.05 M disodium ethylenediamine tetraacetate is equivalent to 23.72 mg of AlK(SO4)2 ·12H2O. b) Anhydrous form Weigh accurately about 0.8 g of powdered Aluminium Potassium Sulfate, previously dried at 200° for 4 hours. Add 100 ml of water, dissolve by heating in a water bath and shaking, filter, and wash the insoluble residue thoroughly with water. Combine the filtrate and the washings, add water to make exactly 200 ml. Measure 25 ml of this solution, add 50 ml of 0.01 mol/l EDTA, and heat to boiling. Cool and add 7 ml of 14% sodium acetate solution and 85 ml of absolute ethanol. Titrate the excess EDTA with 0.01 mol/l zinc acetate using 3 drops of xylenol orange TS as indicator. The end point is when the yellow colour of the solution changes to red. 1ml of 0.01 mol/l EDTA = 2.5821 mg of AlK(SO4)2
Identification
- Solubility (Vol. 4)
- Freely soluble in water; insoluble in ethanol
- pH (Vol. 4)
- 3.0 - 4.0 (10% solution)
- Test for aluminium
- Passes test 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.”
- Test for sulfate (Vol. 4)
- Passes test
- Test for potassium (Vol. 4 )
- Passes test
Purity criteria
- Ammonium salts
- Heat 1 g of the sample with 10 ml of sodium hydroxide TS on a steam bath for 1 min. The odour of ammonia is not perceptible.
- Fluoride
- Not more than 30 mg/kg See description under TESTS
- Lead (Vol. 4)
- Not more than 5 mg/kg Determine using an AAS/ICP-AES technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the methods described in Volume 4 (under “General Methods, Metallic Impurities”).
- Selenium (Vol. 4)
- Not more than 30 mg/kg Test 0.2 g of the sample as directed in the Limit Test (Method II).
- Test: Fluoride
- Lime Suspension Carefully slake about 56 g of low-fluoride calcium oxide (about 2 mg/kg F) with 250 ml of water, and add 250 ml of 60% perchloric acid slowly and with stirring. Add a few glass beads, and boil to copious fumes of perchloric acid, then cool, add 200 ml of water, and boil again. Repeat the dilution and boiling once more, cool, dilute considerably, and filter through a fritted glass filter, if precipitated silicon dioxide appears. Pour the clear solution, with stirring, into 1000 ml of a 1 in 10 sodium hydroxide solution, allow the precipitate to settle, and siphon off the supernatant liquid. Remove the sodium salts from the precipitate by washing 5 times in large centrifuge bottles, shaking the mass thoroughly each time. Finally, shake the precipitate into a suspension and dilute to 2000 ml. Store in paraffin-lined bottles and shake well before use. 100 ml of this suspension should give no appreciable fluoride blank when evaporated in a platinum dish and treated as directed below under "Procedure", beginning with "Ignite briefly at 600°..." Distillation Apparatus Connect a 125-ml distillation flask with a condenser. Equip also with a thermometer and a capillary tube, both of which must extend into the liquid. Connect a small dropping funnel or a steam generator to the capillary tube. Support the flask on an asbestos mat with a hole, which exposes about one-third of the flask to the flame. To minimize the distillation blank resulting from fluoride leached from the glassware, the distillation apparatus should be treated as follows: treat the glassware with hot 10% sodium hydroxide solution, followed by flushing with tap water and rinsing with distilled water. At least once daily, treat in addition by boiling down 15-20 ml of a 1 in 2 sulfuric acid solution until the still is filled with fumes; cool, pour off the acid, treat again with 10% sodium hydroxide solution, and rinse thoroughly. Procedure Add to the distilling flask 1.67 g of the sample, accurately weighed, and 25 ml of a 1 in 2 sulfuric acid solution. Distil until the temperature reaches 160°, then maintain at 160° to 165° by adding water from the funnel, collecting 300 ml of distillate. Oxidize the distillate by the cautious addition of 2 or 3 ml of fluoride-free 30% hydrogen peroxide (to remove sulfites), allow to stand for a few min, and evaporate in a platinum dish with an excess of Lime Suspension. Ignite briefly at 600°, then cool and wet the ash with about 10 ml of water. Cover the dish with a watch glass, and cautiously introduce under cover just sufficient 60% perchloric acid to dissolve the ash. Add the contents of the dish through the dropping funnel of a freshly treated distilling apparatus (the distilling flask should contain a few glass beads), using a total of 20 ml of 60% perchloric acid for dissolving the ash and transferring the solution. Add 10 ml of water and a few drops of a 1 in 2 silver perchlorate solution through the dropping funnel. Continue as directed in the Limit Test, Method I, Thorium Nitrate Colorimetric Method, beginning with "Distil until the temperature reaches 135° ...".
Every name it appears under
90 recorded names. A label may use any of them.
E number
- E522
CAS registry number
- 10043-67-1
- 15007-61-1
- 7784-24-9
As it appears in regulation
- Aluminium potassium sulphate
- Aluminum potassium sulfate
Other names
- 09OXB01F3O
- Alaun
- AlK(SO4)2
- Alum potassium
- Alum, N.F.
- Alum, potassium anhydrous
- Alumen
- Aluminium potassium bis(sulphate)
- Aluminium potassium sulfate
- aluminium potassium sulfate (1/1/2)
- ALUMINIUM POTASSIUM SULFATE (1:1:2)
- Aluminium potassium sulfate, anhydrous
- Aluminium potassium sulphate
- Aluminium potassium sulphate anhydrous
- ALUMINIUM POTASSIUM-SULFATE DODECAHYDRATE
- aluminium(3+) ion potassium disulfate
- Aluminum potassium alum
- Aluminum potassium disulfate
- Aluminum potassium sulfate
- ALUMINUM POTASSIUM SULFATE (1:1:2)
- Aluminum Potassium Sulfate (1:1:2) Dodecahydrate
- Aluminum potassium sulfate (AlK(SO4)2)
- Aluminum potassium sulfate (KAl(SO4)2)
- ALUMINUM POTASSIUM SULFATE, ACS
- Aluminum potassium sulfate, alum
- Aluminum potassium sulfate, anhydrous
- Aluminum potassium sulfate, puriss., anhydrous, calcined, >=98% (calc with ref. to anhyd. subst.), powder
- ALUMINUM POTASSIUM SULPHATE
- ALUMINUM POTASSIUM SULPHATE (1:1:2)
- ALUMINUM POTASSIUM SULPHATE ANHYDROUS
- ALUMINUMPOTASSIUMSULFATE
- Bestmade Natural Products Alum (Kali Alum Sulph)
- CCRIS 6842
- Dialuminum dipotassium sulfate
- E 522
- Exsiccated alum
- HSDB 2685
- INS NO.522
- INS-522
- Kalinite
- NHS CONSTIPATION
- Potash alum
- POTASH-ALUM
- Potassium alum
- Potassium alum anhydrous
- Potassium Aluminium Sulfate
- Potassium aluminum alum
- potassium aluminum disulfate
- Potassium aluminum sulfate
- Potassium aluminum sulfate (1:1:2)
- POTASSIUM-ALUM
- POTASSIUM-ALUM-
- Rxhomeo Homeopathic Combo
- Sulfuric acid, aluminium potassium salt (2:1:1)
- Sulfuric acid, aluminum potassium salt (2:1:1)
- Tai-Ace K 150
- Tai-Ace K 20
Systematic names
- aluminum;potassium;disulfate
- aluminum;potassium;disulfate;dodecahydrate
Hazard reference values
| Type | Value | Population | Assessed by | Opinion |
|---|---|---|---|---|
| ADI | not allocated | — | JECFA | 1978 |
Evidence and how bodies read it
What assessing bodies concluded
Each conclusion is paraphrased in the body's own framing, from the published opinion linked beneath it. Where bodies differ, both stand; this site does not adjudicate between them or add a view of its own.
EFSA 2018
The ANS Panel concluded that aluminium sulphates (E 520–E 523) and acidic sodium aluminium phosphate (E 541), which are permitted in only a few specific products with exposure probably near zero, are of no safety concern at current authorised uses and use levels.
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 E 522?
- E 522 is Aluminum potassium sulfate. Aluminium potassium sulfate, a form of alum, is a firming agent used in pickles and a component of some baking powders.
- What is Aluminum potassium sulfate used for in food?
- It is listed as a firming agent — the role Canada and the US assign it. This page shows every function each regulator records, with the citation for each.
- Where is Aluminum potassium sulfate permitted?
- Of the seven regulators this site reads, Canada, the EU, Great Britain, Japan, South Korea and the US 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 Aluminum potassium sulfate vegan?
- Yes. Aluminum potassium sulfate is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.
Sources for this page
- ca retrieved 2026-10-17
- eu retrieved 2026-10-18
- gb retrieved 2026-10-18
- jp retrieved 2026-10-18
- kr retrieved 2026-10-18
- ecfr retrieved 2026-10-17
- euspecs retrieved 2026-10-18
- jecfaspecs retrieved 2026-09-23
Full licence terms and publisher details on Sources. How this page is built and updated: Method.
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