What is Sodium Aluminum Sulfate (E521) in Baking powder? Uses, Safety, Side effects 

What is Sodium Aluminum Sulfate (E521) in Baking powder? Uses, Safety, Side effects 


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Sodium Aluminium Sulfate (E521) is a chemical compound of aluminium and sodium. It is a white crystalline powder which is powdered with a saline texture, and it’s hygroscopic nature makes it unreliable as a dehydrant. It is also used in the curing of cement and plaster. While Sodium Aluminum Sulfate has a lot of industrial uses, its major use is as an emulsifier or leavening agent of baking powder. Here we’ll discuss briefly, what is Sodium Aluminum Sulfate (SAS), how it functions as an emulsifier, and the side effects or constituents it contains or can be associated with.

What is sodium aluminum sulfate?

Sodium aluminum sulfate, CAS number: 1333-83-3, is a common inorganic salt used as a food additive and in the manufacturing process of some pharmaceuticals. It is also known as alum or potash alum.

Sodium aluminum sulfate is a white powder with a molecular weight of 196.9 g/mol and a molar mass of 208.81 g/mol. It is soluble in water at concentrations greater than 1M and has an ionic radius of 0.67 nm.

Sodium aluminum sulfate formula

Sodium aluminum sulfate formula is a chemical compound with the molecular formula NaAl(SO4)2. It is an inorganic salt that is an important raw material for producing other chemicals. In addition to its use in manufacturing, it is also used as a food additive and as a remedy for upset stomachs. The compound has many other applications, such as in purifying drinking water and wastewater treatment.

The chemical formula of sodium aluminum sulfate is NaAl(SO4)2, which can be written as Na[Al(SO4)3] or Na3[Al(SO4)3]. The chemical formula indicates that the compound contains sodium (Na), aluminum (Al), sulfur (S), oxygen (O) and hydrogen (H). This particular chemical formula shows that there are three molecules of Al(SO4)3 per molecule of Na[Al(SO4)3].

Sodium aluminum sulfate baking powder

Sodium aluminum sulfate is a chemical compound used in baking powder. It is also known as Aluminium monosulfate and Alum. It is a white crystalline powder that dissolves in water.

Sodium aluminum sulfate has many uses in the food industry. It is used to improve the texture of baked goods, such as cakes, cookies, and breads. The addition of sodium aluminum sulfate to the dough or batter helps create a lighter texture in baked goods because it reduces gluten development during baking. This allows for greater volume during rising, which gives baked goods a lighter texture when cooked.

It also contributes to browning in baked goods by accelerating the Maillard reaction (the chemical reaction between amino acids and reducing sugars that produces brown pigments).

Baking powder without sodium aluminum sulfate

Baking powder is a leavening agent that consists of a mixture of bicarbonate salts, an acid salt and starch. The acid salt reacts with the sodium bicarbonate to produce carbon dioxide gas. The acid salt is usually sodium aluminum sulfate but in some countries it can be ammonium alum.

The function of baking powder is to create carbon dioxide when heated which causes the batter or dough to rise.

Sodium aluminum sulphate (SAS) is added to some brands of baking powder to improve the quality and consistency of the product. However, SAS may cause health problems as it is known to be toxic in large doses. It can also cause skin rashes and other allergic reactions in some people.

What is sodium aluminum sulfate made of?

Sodium aluminum sulfate is a white powder with a molecular formula of NaAl(SO4)2 which is used in water purification, wastewater treatment and oil field applications. Sodium aluminum sulfate is also used in the manufacture of paper, textiles and detergents.

Sodium aluminum sulfate is manufactured by the reaction of sodium hydroxide with aluminum sulfate. The resulting mixture is then heated until it decomposes into sodium aluminate and sulfur trioxide gas. The gaseous sulfur trioxide reacts with molten sodium aluminate to produce sodium aluminum sulfate crystals which are filtered and dried to yield finished product.

How is sodium aluminum sulfate made?

Sodium aluminum sulfate is made by mixing sodium sulfate with aluminum sulfate solution and then adding alcohol.

1. Sodium sulfate solution with aluminum sulfate solution:

The first step of making sodium aluminum sulfate is to mix a sodium sulfate solution with an aluminum chloride solution. The reaction between the two solutions produces aluminum hydroxide, which reacts with the sodium hydroxide in the second step of the process. Here is the chemical reaction equation:


2. Adding alcohol:

In order to remove any remaining impurities from the mixture, it can be heated in an oven at 500 °F (260 °C). This will cause any impurities that may have been left over from earlier steps to react with each other and form new compounds.


Molar mass 458.28 g/mol
Density 1.6754 (20 °C)
Boiling point 330 °C
Solubility in water 208 g/100 ml (15 °C)
Melting point 61 °C (142 °F; 334 K)
Coordination geometry Octahedral (Na+); Octahedral (Al3+)




Other names Aluminum sodium sulfate, Soda alum
CAS number 7784-28-3
Chemical formula AlNa(SO4)2 · H2O (anhydrous), AlNa(SO4)2 · 12H2O (Dodecahydrate)
Molecular weight 242.09 (anhydrous)


Colorless crystals or white powder


Anhydrous dodecahydrate is slowly soluble in water, while dodecahydrate is freely soluble. Both types are insoluble in ethanol.

Is sodium aluminum sulfate basic or acidic?

The sodium aluminium sulfate solution is a weak acid. It dissociates Al3+ when dissolved in water and releases H+ when reacting with water. An equation describing the reaction is as follows:

Al3+ + 3H2O — AI(OH)3 + 3H+

What is sodium aluminum sulfate used for?

Sodium aluminum sulfate is a chemical compound that’s used in many products. It’s most commonly found in items like toothpaste and deodorant, but it can also be found in pharmaceuticals and cosmetics.

Sodium aluminum sulfate in food

Sodium aluminum sulfate is used primarily as an anti-caking agent for powdered foods like flour, sugar, salt and spices. It helps prevent clumping of these powders by absorbing moisture from the air. This prevents the particles from sticking together and improves the flowability of dry foods. Sodium aluminum sulfate may also be used as a leavening agent in baked goods.

Sodium aluminum sulfate is a slow-acting leavening acid that is commonly combined with monocalcium phosphate (a fast-acting leavening acid), baking soda (alkali) and cornstarch (moisture absorber) as double-action baking powder. When baked, double-action baking powder contains two types of leavening acids, which react with sodium bicarbonate at different times to release carbon dioxide.

When mixed with water, the first acid (monocalcium phosphate) immediately reacts with sodium bicarbonate. Baking soda reacts with sodium aluminum sulfate once it is heated in the oven. This is because SAS must dissolve in water at a higher temperature for the reaction to take place.

Based on the reaction principle of SAS with baking soda:

Al3+ + 3HCO3- — AI(OH)3 +3CO2

Foods that may contain it include:

  • Cakes, pastries, donuts, crackers and pies
  • Tortillas
  • Cheese (to increase its acidic nature)
  • Confectioneries
  • Cereal flours

Sodium aluminum sulfate in baking powder

Sodium aluminum sulfate is added to baking powders because it reacts with acids in the batter to release carbon dioxide gas bubbles that cause cakes to rise as they bake. The reaction between sodium aluminum sulfate and acids also helps prevent staleness by reducing the pH level of batters made with acidic ingredients such as sour cream or buttermilk.

Sodium aluminum sulfate in cosmetics

Sodium aluminum sulfate has been used in cosmetics since at least the early 1900s when it was included in face powders and rouges to provide color to those products. Today it is still used in some cosmetic creams where its function may include coloring, thickening or stabilizing the product.

Sodium aluminum sulfate in pharmaceuticals

Sodium aluminum sulfate is used to control the viscosity of liquid medications, such as cough syrups, eye drops and suppositories. It also serves as a binding agent in pills or tablets that are designed to dissolve slowly over time. It has also been used as an antibacterial agent and an antifungal agent in medical devices.

Sodium aluminum sulfate in industry

In industry, it is used as a flocculant and clarifying agent in water treatment, to remove limescale from pipes and boilers. It is also used in the manufacture of paper, textiles and ceramics, and in the creation of synthetic gems.

Sodium aluminum sulfate can be used as a desiccant (an agent that dehydrates materials) to remove moisture from industrial processes like oil refining; it also helps to reduce corrosion by absorbing acid gases in some industrial settings.

Is Sodium Aluminum Sulfate Safe to Eat?

There is no doubt that SAS is safe as a food additive, and it has been approved by a number of authorities, including the U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA), the UK Food Standards Agency, as well as the Joint FAO/WHO Expert Committee on Food Additives (JECFA).


It is generally recognized as safe (GRAS) when used in accordance with good manufacturing practices.


There is a listing for sodium aluminum sulfate (E521) in the Commission Regulation (EU) No 231/2012 as a food additive that has been authorized. It is included in the category “Additives other than colours and sweeteners”.

Safety re-evaluation in 2018

In the current authorised uses and levels of use, sodium aluminum sulfate is not considered a safety concern by the EFSA. In the meantime, aluminium compounds have low bioavailability, low acute toxicity, and no potential genotoxicity or carcinogenic properties.


Acceptable daily intake: Since 1978, no ADI has been allocated.

What are the benefits of sodium aluminum sulfate?

Sodium aluminum sulfate is a mild acid, pH 4.0-6.0. It is used to control pH in the following industries: paper, textile and dyeing, battery, leather and tanning, metals and mining, food and beverage processing and water treatment.

Sodium aluminum sulfate has many industrial uses. It is used in the paper industry as an acidity regulator in pulp mills to maintain a proper pH balance when treating wood chips or other cellulose-containing materials to make paper. It can also be added to bleach solutions to help control the bleaching process by combining with other chemicals that can cause discoloration of the final product during manufacture. In textile manufacturing, sodium aluminum sulfate helps remove starch from cotton before spinning it into thread or yarn for weaving or knitting into fabrics for clothing or home furnishings.

Sodium aluminum sulfate also has applications in the battery industry. It is used as a component of electrolytes for lead-acid batteries in cars, trucks and boats as well as for nickel-cadmium batteries found in many consumer electronics such as laptop computers and cell phones. In addition, sodium aluminum sulfate may be added to an electrolyte solution used to plate pure gold onto jewelry such as rings or earrings.

What are the side effects of sodium aluminum sulfate?

Sodium aluminum sulfate side effects

The side effects of sodium aluminum sulfate include:

  1. Allergic reactions. Sodium aluminum sulfate can cause an allergic reaction in some people. Symptoms may include hives, rash and swelling of the face, lips and throat.
  2. Increased risk of infection. Your doctor may tell you to avoid contact with people who have infections or to avoid crowds when you are on this medication. This is because sodium aluminum sulfate can lower your resistance to infection.
  3. Low blood pressure (hypotension). Sodium aluminum sulfate can make it difficult for your blood to clot (thrombocytopenia), which increases your risk of bleeding. Your doctor may tell you to avoid activities that might increase your risk of bleeding or injury while taking this medication.
  4. Decreased red blood cell counts (anemia). Sodium aluminum sulfate can decrease the number of red blood cells in your body, making it harder for your body to get oxygen from the air you breathe into your lungs. This side effect occurs most often in people who have kidney problems or who take large doses of this drug for a long time (such as those using it as a laxative).

Is sodium aluminum sulfate bad for you?

Sodium aluminum sulfate (SAS) is a chemical compound that is used for a variety of purposes in the food industry. It is often used as an additive in processed foods to improve their texture and appearance.

SAS is also used as an ingredient in personal care products, such as shampoo and toothpaste, because it has been found to be an effective antiperspirant agent.

SAS has been used for many years by the food industry and it has been deemed safe to consume by both the European Food Safety Authority (EFSA) and the U.S. Food & Drug Administration (FDA).

However, there are some concerns over its safety because there have been reports of allergies caused by exposure to SAS or its breakdown products.

Where to buy sodium aluminum sulfate?

Sodium aluminum sulfate, sometimes called Alum, is used in water treatment and as a flocculant in the textile industry. It is also known as an antiperspirant and deodorant ingredient.

Alum can be found in drug stores or health food stores. It can also be bought online through many websites including Amazon and eBay.

Frequently asked questions

Is sodium aluminum sulfate natural?

No, sodium aluminum sulfate is not natural. It is a manufactured chemical that has been used to purify water and remove minerals from oil, paint, and pulp and paper production.

Is sodium aluminum sulfate halal?

No, sodium aluminum sulfate is not halal. It contains sulfur, which is haram (forbidden) for Muslims to consume.

Is sodium aluminum sulfate vegan?

No, sodium aluminum sulfate is not vegan. It is made from the reaction of sodium hydroxide and aluminum sulfate, which involves the use of animal products.

Is sodium aluminum sulfate kosher?

Yes, sodium aluminum sulfate is kosher, because it’s made up of kosher-certified ingredients (salt and sulfuric acid), and there is no additional processing required to make it kosher.

Is sodium aluminum sulfate gluten free?

Yes, sodium aluminum sulfate is gluten-free because it does not contain wheat, rye, barley, or oat flour.

There are many different kinds of food additives that are used in processed foods, but sodium aluminum sulfate is not one of them.


Sodium Aluminum sulfate seems to be a metal additive in the baking powder which helps to make much more active leavening agents. This one compound can demonstrably avoid cold welding and has the ability to produce a series of functional surface features. It’s widely used as a chemical reagent in the industry of paper, textile, food and medicine.

Sophie Feng

Sophie Feng

Sophie Feng is the author of gradechemical.com, she is the co-founder of the grade chemical network. She has been in grade chemical company since 2017, with a working knowledge of food chemical .

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