What Is Boric Acid?

Jul. 17, 2020

Boric AcidBoric acid and borax are not legal food additives, but there are still unscrupulous players who illegally use the two to increase the elasticity and toughness of the food, extend the shelf life or keep the color beautiful, even in addition to alkaline rice dumplings, other Foods such as rice cakes, oil noodles, dumplings, fish plates, and shrimps that often seek "taste" are also often affected.

After all, how does borax and boric acid affect the human body? Let us first briefly understand the structure and characteristics of borax and its relationship with "boric acid".

Conversion between borax and boric acid

Borax, also known as sodium tetraborate, has a chemical formula of Na2B4O7. It is a common boron-containing salt with the appearance of colorless crystals or white powder. It can inhibit the growth of yeasts and molds. It has been used as a preservative. It can also inhibit the action of tyrosinase and prevent the oxidation of tyrosine to melanin. In recent years, it has been abused to prevent shrimp food black. To maintain its beautiful color.

Borax is easily soluble in water, and B4O72- anion can form the protagonist of this article with water molecules-boric acid (H3BO3), and hydroxide ion (OH-), so it is alkaline. The boric acid molecules in the aqueous solution will further combine with the hydroxide ions to produce borate ions (B(OH)4–). The "-OH groups" on both sides can be combined with the -OH groups in the long-chain molecules in food. The group reaction forms bonds and acts as a bridge between long chains, so that long chain molecules can form a 3D network structure, which is the key to making borax make food more Q-elastic.

Similarly, borax will be acidified to boric acid in an acidic solution, such as sulfuric acid or hydrochloric acid, but due to the low concentration of hydroxide ions, no further borate ions will be generated. In short, boric acid is a product of borax dissolved in water or combined with acid, so when the food reacts with the borax solution, borax and boric acid will often remain in it. After eating, the stomach juice is acidic , Borax will be converted into boric acid in the body.

Boric acid common in nature

Boric acid is a boron-containing inorganic weak acid. The appearance is white powder or transparent crystals. It feels greasy to the touch. It is slightly soluble in cold water, but its solubility will increase with increasing temperature. At 20°C, 1 liter of Water is about 47.2 grams of boric acid. Boric acid is actually quite common in nature: seawater itself contains boric acid and other salts; in some special volcanic areas, such as Tuscany and Lipari Islands in Italy and Nevada in the United States (Nevada), you can also find its trail. Sometimes, boric acid coexists with boron-containing minerals (such as borax ore), interspersed in the mineral structure.

In addition, boron is also indispensable for the growth of plants. It can promote the production of lignin and the growth of rhizomes. If boron is lacking, the plants will turn yellow or black, and even the shape of the leaves is poorly developed. These boron elements are often stored in plants in the form of "boric acid", especially fruit trees and fruits. Therefore, ingesting trace amounts of boric acid is not an earth-shattering thing, the human body can also be metabolized naturally without harming health.

Other applications of boric acid: disinfection, deworming, buffer

In addition to helping plants grow naturally, boric acid is also used in medicine. It has a disinfecting effect, can treat minor cuts and burns, and can also inhibit mold infections (such as Candida or athlete's foot). It is often used as a dressing or ointment. To use. The diluted boric acid aqueous solution (maximum allowable concentration is 3%) can be used as eye drops or eye wash to relieve eye discomfort and is currently the only acid known to be beneficial to the eyes.

In addition, boric acid has the function of killing common pests (borax also has the same effect). The main mechanism is to corrode the exoskeleton of insects and affect its metabolism by ingesting food. In 1948, the United States Environmental Protection Agency (USEPA) used boric acid to control the number of cockroaches, termites, red fire ants, silverfish, and fleas; and this also has the characteristics of disinfection and insecticidal effects, which also allows It is used as a preservative for wood. Other uses of boric acid include: controlling the rate of nuclear fission reactions in nuclear power plants, manufacturing heat-resistant glass (borosilicates), and an aqueous solution of boric acid and its borate can be used as an acid-base buffer for swimming pools.

Silane suppliers remind you that boric acid cannot be added to food

Although boric acid itself is not very toxic, it has a "cumulative effect" in the body. Although it is not consumed every time, it accumulates in the body after continuous intake. It may still damage the central and digestive system, hinder the function of digestive enzymes, cause loss of appetite, and inhibit nutrition Absorb and promote fat breakdown, leading to weight loss and other symptoms. In addition, in the study of boric acid feeding in mice, mice and dogs, it was also observed that long-term or short-term intake of large amounts of boric acid or borax will affect the male reproductive system, such as testicular atrophy. However, at this stage, boric acid has not been observed to be significantly carcinogenic or result of gene mutations, nor has the International Cancer Research Center (IARC) listed it as a carcinogen.

In terms of dosage, adults taking 1 to 3 grams of boric acid will produce "boric acid poisoning" symptoms, including vomiting, diarrhea, skin erythema, and even the risk of shock or coma; oral lethal doses are 15 to adult 20 grams, infants 5-6 grams, and infants 2-3 grams.

Therefore, FAO and WHO JECFA believe that borax and boric acid are potentially harmful to human health, so they should not be used as food additives. The World Health Organization (WHO) recommends that the "daily intake allowance (TDI)" of boric acid is 0.16 mg/kg bw/day, that is, the daily intake of 0.16 mg per kilogram of body weight is allowed. At present, most countries in the world prohibit the use of borax or boric acid as food additives (although the EU allows borax or boric acid to be used as a preservative for caviar), Taiwan has also explicitly banned it - our food additives are listed positively, and borax is not in In the permission list.

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