What is Sodium Metabisulfite (E223) in food? Uses, Safe, Side Effects

What is Sodium Metabisulfite (E223) in food? Uses, Safe, Side Effects


Table of Contents

Sodium metabisulfite (also known as sulfur dioxide, sulfite, and E223), is a sulfite that can be widely used in the food industry and is currently a commonly used food additive that can be used as a preservative, bleach, and antioxidant. Its European Food additive number is E223. At the same time, it can also be used as a reducing agent, the function is to preserve fresh and dried fruits, vegetables, and wine.

What is sodium metabisulfite?

Sodium metabisulfite is an organic salt that is used as a preservative in foods and beverages. It is also used to bleach textiles and paper, to bleach hair, and as a bleaching agent for metals such as copper and brass.

Sodium metabisulfite has the chemical formula Na2S2O5, which means it contains two atoms of sodium (Na), two sulfur atoms (S), and five oxygen atoms (O). It has the appearance of a white powder or granules that are soluble in water. The chemical formula of sodium metabisulfite is Na2S2O5. Sodium metabisulfite is usually sold as an odorless white powder or granules that are soluble in water when dissolved.

What is sodium metabisulfite used for?

Sodium metabisulfite is used to preserve food and wine. It is also used in the manufacturing of paper, rubber, textiles, dyes and photographic film.

Sodium metabisulfite is also known as sodium pyrosulfite or disodium sulphitedisulfite. It can be used for a variety of purposes including preserving food items and wines, as well as in food production. Sodium metabisulfite is also used in the manufacturing of paper, rubber, textiles, dyes and photographic film.

In addition to its use as a preservative in food products, sodium metabisulfite is also used as a bleaching agent in laundry detergents and cleaners.

What is sodium metabisulfite in food?

Sodium metabisulfite is a chemical preservative. It is used in many food products to prevent mold from growing.

Sodium metabisulfite is found in wine, beer and other alcoholic beverages, as well as some brands of barbecue sauce, jam and jelly, baked goods and snack foods. It is also used to bleach paper products such as newsprint.

Sodium metabisulfite can cause allergic reactions in some people. Symptoms include skin rashes, itchiness and hives (raised red welts on the skin). In severe cases, it can cause breathing difficulties and anaphylaxis — a potentially life-threatening allergic reaction that causes swelling of the throat and tongue and may lead to shock if not treated promptly with epinephrine (adrenaline) or steroids.

How is sodium metabisulfite made?

Sodium metabisulfite is made by the reaction between sulfur dioxide and sodium carbonate. The following is the equation for this process: SO2 + Na2SO3 ←→ 2Na2S2O5

In general, Solvay is formed by the reaction of sodium carbonate (sodium carbonate) and sodium bisulfite (NaHSO3) solutions to form a mixed solution of sodium bisulfite and sodium sulfite (sodium sulfite). The basic reaction equation is: Na2CO3+2NaHSO3=Na2SO3+H2O+CO2

By adding a dose of sulfur dioxide (so2) to the above-mixed solution, the sodium bisulfite can be converted to sodium bisulfite, and the dissolved sulfur dioxide is obtained. At this time, its equation is described as Na2SO3+H2O+SO2=2NaHSO3

The dissolved sulfur dioxide is converted to sodium bisulfite by adding alkali components such as sodium carbonate, sodium hydroxide, sodium sulfite, or mixtures. The reaction equation can be written as Na2CO3+H2O+SO2=2NaHSO3+CO2

Sodium metabisulfite (sodium metabisulfite) is obtained from two sodium bisulfite molecules, reacts by cooling the aforementioned sodium bisulfite solution, and undergoes a purification and drying process to produce crystals or powders. The reaction equation can be written as 2NaHSO3=Na2s2O5+H2O


Other names · Disodium pentaoxodisulphate

· Disodium disulfite

· Sodium pyrosulfite

· Sodium disulfite

CAS number 7681-57-4
Chemical formula Na2S2O5
Molecular weight 190.11



The substance is crystals or crystalline powder of white color. Exposure to air or moisture will slowly oxidize the sodium sulfate to sodium sulfate (Na2SO4) and release sulfur dioxide (SO2). When sulfur dioxide reacts with an acid, the reaction releases SO2.


It is soluble in water and its solubility increases with temperature. At 20°C, its solubility in water is 54g/100ml, while at 100°C, it is 81.7g/100ml. When dissolved in water, it produces sodium bisulfite (HSO3−). A 10-percent solution of the substance is acidic and has a pH of 4.0 to 5.5.

Na2S2O5 + H2O = 2 NaHSO3

Glycerin is soluble and ethanol is mildly soluble, but benzene and alcohol are insoluble.



What is the application of sodium metabisulfite?

Sodium metabisulfite is a salt made up of sodium, sulfur, and oxygen. It can also be called sodium hydrogen sulfite or sodium bisulfite. Sodium metabisulfite is a salt consisting of sodium, sulfur, and oxygen. 

It can also be called sodium bisulfite or sodium bisulfite. Sodium metabisulfite is a strong reducing agent, which can react with oxidants such as sulfur atoms, with a positive valence of 4 and a maximum valence of 6. Sodium metabisulfite is therefore a multifunctional ingredient that can be used as a preservative, antioxidant, and bleach in agricultural products, wine, and other edible grade products; 

It can be used for bleaching cotton fabric and organic matter, as well as in dye, paper, leather, chemical synthesis and other industries as reducing agent.

 Sodium metabisulfite helps prevent browning in apples by reacting with phenolic compounds. It also prevents oxidation during the processing and storage of apples which results in better color stability of apples after storage.


SMBS is a sulfur-containing preservative used in food to prevent the growth of microorganisms such as molds and yeasts. It acts by inhibiting the oxidase, which prevents normal physiological oxidation processes in microorganisms. This causes inhibition of reproduction and thus helps preserve food.


As a strong reducing agent, sulfite can chemically react with oxygen in fruits and vegetables. Therefore it can keep fruits and vegetables from spoiling by preventing oxidation, which keeps the vitamin C in them from breaking down.

Bleaching agent

Keep the material’s color bright and fresh by reducing the presence of colored substances or slowing down browning, which is called oxidative browning.

The main application of Sodium metabisulfite in food are as follows:


You may have noticed the presence of sulfur dioxide in the ingredients list of wine, but unlike other ingredients on the label, sulfur dioxide isn’t added to wine directly. In fact, it’s formed by adding either sodium metabisulfite or potassium metabisulfite. The following equation shows what happens when Na2S2O5 reacts with wine:

  1. Na2S2O5 + H2O 2Na+ + 2(HSO3)-
  2. HSO3- + H+ H2O + SO2

Sulfur dioxide is indispensable in every phase of winemaking, from grape harvesting to bottling. It’s used to inhibit the growth of yeast and bacteria—so the wine stays fresh longer and has a longer shelf life.

There is a common practice of adding sodium metabisulfite or potassium metabisulfite to wine, cider, or maybe beer as an antioxidant, preservative, and stabilizer. Wine equipment and wine bottles can also be cleaned and sanitized with it.


As with L-cysteine, sodium metabisulfite, which is often used in making pastries, reduces the dough’s rest time by reacting with disulfide bonds. This process generates thiosulfate esters in gluten protein after hydrolyzed to bisulfite (HSO3−) in water.

Processed fruit products

As with other sulfites (such as sodium sulfite, and sulfur dioxide), sodium metabisulfite slows browning reactions in processed fruit products and inhibits the growth of certain microorganisms.


The following applications are possible for sodium metabisulfite of industrial grade:

  • Pharmaceuticals: sodium metabisulfite is used to purify chloroform, phenyl propyl sulfone, and benzaldehyde.
  • Rubber: a coagulant.
  • Printing and dyeing: to dechlorinate bleached cotton.
  • Leather: the process of imparting leather with soft, waterproof, and folding-resistance properties is known as tanning.
  • Surfactants and polymerization: can be used as a sulfonation and a reducing agent.
  • Gold refining: itis a reducing agent that reduces Au³ to precipitate gold from an aqueous solution.

Is sodium metabisulfite safe?

Yes, sodium metabisulphite has essentially no side effects. Its safety has been certified by several authorities, such as the US Food and Drug Administration (FDA) and the European Food Safety Administration (EFSA), and the FAO / WHO Joint Expert Committee on Food Additives (JECFA).

According to the FDA, sodium metabisulfite is generally recognized as safe (GRAS) as a preservative in foods except for fresh fruits and vegetables, canned meats, and products containing thiamine (vitamin B1).


Sodium metabisulfite is authorized for use in foodstuffs as a preservative under Commission Regulation (EU) No 231/2012. It is grouped in the “additives other than colors and sweeteners” category.

Safety re-evaluation in 2016

According to EFSA, the current ADI for E220-E228 is 0.7mg, expressed as SO2 equivalent/kg bw per day, which is temporary and will be re-evaluated in light of uncertainties and limitations in the database.

Approved uses

The substance is listed together with sulfur dioxide (E220), sodium sulfite (E221), sodium bisulfite (E222), potassium metabisulfite (E 224), calcium sulfite (E226), calcium bisulfite (E227), and potassium bisulfite (E228) in the FAO/WHO Codex Alimentarius. The maximum use levels are 10-2000 mg/kg.

The following food may contain sodium metabisulfite:

  • Some fresh fruits and vegetables contain table grapes, peeled potatoes, peeled and frozen potatoes, dried coconut, dried mushrooms, dried ginger, dried tomatoes, pears, and bananas.
  • Mermelard, jams, and jellies
  • Cookies desserts
  • Drink or wines, such as cider and perry, beer and malt beverage, fruit wine, and other Brewed wine.

UK Food Standards Agency

Classified as “Preservatives”

Food Standards Australia New Zealand

Code number 223 applies to this ingredient in Australia and New Zealand.


Function grade: food additives, antioxidants, flour treatment agent, preservatives.

Acceptable daily intake (ADI): “0-0.7mg/kg BW”

What are the side effects of sodium metabisulfite?

It is possible that sodium metabisulphite can cause asthma-like allergic reactions and untoward effects as follows:

  • Skin, eye, and respiratory tract irritation are common symptoms of exposure to this chemical.
  • Headaches
  • expiratory dyspnea
  • Nausea
  • Vomiting
  • Diarrhea

Sulfur dioxide can irritate the respiratory tract, and its residue may produce sulfite and sulphuric acid. The combination of these chemicals can have a stimulating effect on the lungs and induce various respiratory tract inflammatory diseases.

Sulfur dioxide is a strong toxin that can destroy the activity of enzymes in the body, preventing them from metabolizing carbohydrates and proteins. It also decomposes vitamin B.

When sodium metabisulfite is added to water, it forms sulfuric acid. The reaction is an oxidation-reduction reaction, which means that electrons are transferred from one molecule to another.

Sodium metabisulfite has three oxygen atoms in its molecular structure. You can see this by looking at the chemical formula for sodium metabisulfite: Na2SO3. Each oxygen atom has a negative charge of -2 and two sulfite groups (SO3) have six electrons each. So, when you add sodium metabisulfite to water, you transfer six electrons from the sulfites of sodium metabisulfite to the water molecules, making hydrogen ions (H+) in the process. In other words, you make sulfuric acid!

You can also look at this reaction as an oxidation-reduction reaction:

Na2SO3 + H2O –> 2H+ + SO42-

This is because when you remove an electron from an atom or molecule, it becomes positively charged (oxidized). On the other hand, if you add an electron back onto an atom or molecule that had one removed beforehand, it becomes negatively charged (reduced). In this case, since there are more hydrogen ions than sulfites after mixing the two reactants together, the reaction will continue to produce more hydrogen ions until all of the sulfites have been used up.

Where to buy sodium metabisulfite?

Sodium metabisulfite can be purchased at retail stores, such as drugstores and grocery stores, in the laundry section of the store. Laundry detergents containing sodium metabisulfite are also available at retail stores.

If you are looking for a specific brand of sodium metabisulfite, check the label on the bottle before buying it. If you are unable to find it locally, try online retailers such as Amazon or eBay.

If you buy a large quantity for your company, you can consider purchasing from Grade Chemical, Which is one reliable food additives supplier in China. they can supply you much more competitive price than the local market price.

Frequently asked questions

Is sodium metabisulfite natural?

Sodium metabisulfite is a chemical compound that is used to preserve foods, particularly wine. It can also be found in shampoo and other personal care products.

Sodium metabisulfite is not harmful, but it can cause an allergic reaction in some people. If you have an allergy to sulfites, you should avoid sodium metabisulfite.

If you are not allergic to sulfites, then sodium metabisulfite is safe to consume. However, it is important to avoid consuming large amounts of sodium metabisulfite because it has been linked to stomach ulcers and even cancer.

Is sodium metabisulfite vegan?

Sodium metabisulfite is considered vegan because it is not an animal product or byproduct. However, since it is an additive that’s not naturally occurring in food products, it should be avoided by vegans if possible.

Is sodium metabisulfite used as a preservative?

Sodium metabisulfite is used as a preservative in some foods. It can help prevent the growth of bacteria, yeast, and mold in foods like beer, wine, and salad dressings.

What is the difference between sodium metabisulfite and potassium metabisulfite?

Both ingredients are used in the making of wine. They add sulfites to the wine. They differ in that sodium metabisulfite adds sodium ions to the wine while potassium metabisulfite leaves potassium ions behind.

Potassium metabisulfite is usually preferred over sodium metabisulfite because of the following three reasons:

  1. Avoid sodium-rich foods that will raise blood pressure.
  2. Tartaric acid is stabilized and released by potassium ions.
  3. The salty taste of the wine is caused by sodium metabisulfite

Difference between Sodium metabisulfite and sodium bisulfite

Sodium bisulfite and sodium metabisulfite are both sulfites, but they have different chemical formulas. Sodium bisulfite has the formula NaHSO3 and the E number E222. It is often used as a mixture of sodium bisulfite and sodium metabisulfite, while pure sodium metabisulfite has the formula Na2S2O5.

The manufacturing process of sodium metabisulfite indicates that it is difficult to produce the pure form of crystal sodium bisulfite as sodium metabisulphite crystallizes.

This is the reason that the European food additive number E222 specifies “sodium hydrogen sulfite in an aqueous solution”—rather than its power or granular form—on its label.


In sum, sodium metabisulfite is a chemical compound and preservative used in foods and beverages to inhibit bacterial and fungal growth. It is typically listed as E223 or SULFUR DIOXIDE on food packaging. Since sodium metabisulfite is a food additive, it is regulated by the U.S. Food and Drug Administration (FDA).

if you have any questions about sodium metabisulfite, please contact us in the below comments.

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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