Tannic acid is a specific commercial form of tannin, a type of polyphenol, is usually extracted from Tara pods, Chinese gallnuts or others. High levels of tannic acid are found in some plant galls such as Chinese gallnuts. These are formed by plants when they are infected by certain insects. These insects pierce the plant leaves and when the egg hatches out into a larva the plant produces a gall which surrounds the larva.
Tannic acid is a polymer of gallic acid molecules and glucose. It will hydrolyze into glucose and gallic or ellagic acid units. Tannic acid is odourless but has a very astringent taste. Pure tannic acid is a light yellowish and amorphous powder. It is highly soluble in water; one gram dissolves in 0.35 ml of water.
According to the definitions provided in external references such as international pharmacopoeia, Food Chemical Codex and FAO-WHO tannic acid monograph only tannins sourced from the above mentioned plants can be considered as tannic acid.
Tannic Acid Application In Food:
Use of tannic acid in food applications is far more widespread and significant amounts are used as process aids in beer clarification, aroma compound in soft drinks and juices. Equally important are applications in the wine industry, where it finds use as a natural clarifying agent, colour stabilizer and taste enhancer. Tannic acids reacts with proteins in wine to form insoluble complexes which sediment or can be filtered.
Tannic Acid Application In Pharmacetical:
People apply tannic acid directly to the affected area to treat cold sores and fever blisters, diaper rash and prickly heat, poison ivy, ingrown toenails, sore throat, sore tonsils, spongy or receding gums, and skin rashes; and to stop bleeding.
Tannic acid is also taken by mouth and applied directly to treating bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer.
Tannic acid may help reduce your risk of cancer when consumed. According to the National Institutes of Health, tannic acid can have an antioxidant effect on your body. Antioxidants help protect your cells from free radicals, which are damaging substances that can lead to cancer and other chronic diseases. They also help protect your cells from mutagens and carcinogens, which also contribute to cell damage and the occurrence of cancer.
Tannic acids help eliminate diarrhea, reduce swelling of hemorrhoids, loosen catarrh in the respiratory system, and control various kinds of internal bleeding. Externally, tannins are beneficial in rubs for aching muscles and joints, in salves for open, slow-healing sores, and as antiseptics. Plants high in tannic acid have been used to treat cancers.
Tannic acid has anti-bacterial, anti-enzymatic and astringent properties. Tannic acid has constringing action upon mucous tissues such as tongue and inside of mouth. The ingestion of tannic acid caused constipation and can be used to treat diarrhoea (in the absence of fever or inflammation). The anti-oxidant and anti-mutagenic properties of tannic acid are beneficial.
Tannic Acid Application In Industrial:
Tannic acid is also used in many industrial applications. The best known is the tanning of leather. In manufacturing, tannic acid is used for tanning hides and manufacturing ink; and to kill dust mites on furniture.
Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion.