By Sonu Susan Mathew

Do you ever know, hydrochloric acid, one of the strongest acids in the world is used as a food additive?

Hydrochloride, also known as hydrogen chloride, exists in solid, liquid, and gaseous forms. Its chemical formula is HCl. Hydrochloric acid is colorless to pale yellow with strong corrosive properties and an irritating odor is the aqueous form of hydrogen chloride. It is found naturally in gastric acid. Hydrochloric acid is also known as muriatic acid, and is using extensively in food, mining, pharmaceuticals, textiles, tannery, and cosmetic industries around the world for various purposes.

The highest percentage of hydrochloric acid produced commercially is using in food industries. Food grade hydrochloric acid (E507) is produced by the direct synthesis of elements- burning of chlorine in hydrogen and then the absorption in the water.

According to FAO, FDA, and Codex Alimentarius, muriatic acid is approved as one of the additives permitted for use under specified conditions in certain food categories or individual food items as an acid regulator in accordance with Good Manufacturing Practices (GMP) across the globe.

Hydrochloric acid is allowed to use in the manufacture of some dairy products, bakery products, cereal, and starch-based products, canned or bottled (pasteurized) or retort pouch vegetables and seaweeds, salads, juices, syrups, beer, preserved eggs, soups, sauces, dietetic foods, and foods for children and infants as an acidity regulator and to help enhance flavor and reduce spoilage.

Hydrochloric acid is using widely in the food industry for the production of high fructose corn syrup (HFCS). HFCS is a liquid alternative sweetener, commercially use to make baked goods, beverages, and other sweetened foods. It is made from corn starch by the process of chemical and enzymatic hydrolysis. Caustic soda and hydrochloric acid are the chemicals using in this process. Calcium chloride (E509) is a food additive using in the food industry produced by the reaction of hydrochloric acid with calcium carbonate.  Hydrochloric acid also plays an important role in water treatment as an acidity regulator and for cleaning or disinfecting. Gelatin is a natural protein present in the bones, skins, and other connective tissues of animals. Acid and alkali treatment is a vital step in its manufacture. Usually, 4% hydrochloric acid is using for acidulating crushed bones for the manufacture of gelatin. Monosodium glutamate was produced by the process of hydrolysis of vegetable proteins using hydrochloric acid is replaced by the process of fermentation. In the brewing industry, 0.1M hydrochloric acid can also be used to increase chloride in water. Aspartame is an artificial sweetener that can be produced by using hydrochloric acid during the esterification process, followed by the addition of a neutralizing agent. In the conventional method to produce invert sugar, hydrochloric acid is used to hydrolyze sugar. The non-brewed method or non-fermented method or chemical hydrolysis is a modern method adopted by so many manufacturers for the production of soy products. Soy proteins are artificially breakdown by hydrolysis. It is a faster method for brewing. Soybeans are boiled in hydrochloric acid for 15-20hrs, followed by neutralization, addition of the other reagents, refining, and packing. In the acid-based manufacture of hydrolyzed vegetable protein, foods such as soy, corn, or wheat are boiled in hydrochloric acid at a temperature of 100–130 °C and then neutralizing the solution with an alkali such as sodium hydroxide. Hydrochloric acid breaks down the protein in vegetables into their components such as amino acids and other peptides. Studies showing that hydrochloric acid is used for the pretreatment of raw materials like molasses, cassava peels in the production of citric acid. Hydrochloric acid is also used for the purification of table salts, modification of corn starch, and rennet production by adjusting pH in the extraction of rennet from the calf stomach.

Hydrochloric acid is considered a hazardous chemical and falls under category 1(highly toxic and severely irritating) when it comes in contact with skin and eyes and category 4(practically non-toxic and not an irritant) when inhales or by mouth in small doses and is not a carcinogen.

Hydrochloric acid in the air severely affects the eyes and respiratory tract. The inflammation in the upper respiratory tract can result in edema and spasm of the larynx.  Hydrochloric acid can burn skin and cause pulmonary edema for the lungs. Small doses, if ingested will not create a serious problem. But ingestion of conc. hydrochloric acid in large amounts can severely injure the mouth, throat, esophagus, and stomach. Hydrochloric acid fumes can irreversibly damage breathing organs, hair, skin, and intestines.

Hydrochloric acid in the air can act as a phytotoxicant to tomatoes, sugar beets, and fruit trees of the Prunus family.  As it is highly water-soluble, hydrochloric acid can reduce the pH of water-bodies and can make it more acidic. Low pH can harm aquatic living organisms.

Citric acid, acetic acid, phosphoric acid, lactic acid, malic acid, and formic acid are some other acidity regulators. Acetic acid is the most common choice in replacing hydrochloric acid, if a weak acid can replace it, in necessary conditions. For high-temperature applications, hydrochloric acid is used in combination with formic or acetic acid, or blends of formic and acetic acid can also be used.  Lactic acid or phosphoric acid can be used instead of hydrochloric acid to lower the pH of the mash in home brewing.

According to the studies conducted by European Food Safety Authority (2019) on hydrochloric acid as a food additive, they concluded that exposure to chloride from hydrochloric acid does not raise a safety concern at the reported use and use levels. Before handling hydrochloric acid, employees must be properly trained and rules and regulations by all departments (Department of Transportation (DOT), Environmental Protection Agency (EPA), and Occupational Safety and Health Act (OSHA) rules and regulations) should be reviewed.

*Food Technologist