Review on tannins: Extraction processes, applications and possibilities

Tannins are found in most of the species throughout the plant kingdom, where their functions are to protect the plant against predation and might help in regulating the plant growth. There are two major groups of tannins, i.e., hydrolyzable and condensed tannins. The tannins are being used as important and effective chemicals for the tanning of animal hides in the leather processing industry since the beginning of the industry. Additionally, the tannins have been using as mineral absorption and protein precipitation purposes since 1960s. These are also used for iron gall ink production, adhesive production in wood-based industry, anti-corrosive chemical production, uranium recovering chemical from seawater, and removal of mercury and methylmercury from solution. Presently, tannins are considering as bioactive compound in nutrition science. It has also been considered for advanced applications, i.e., 3D printing and biomedical devices. The application of tannins as medicine is another new dimension in medical science. This paper outlines the general information about tannins followed by their extraction process. The utilization of tannins has also been presented in a broader scale. Depending on all these information, the article also describes the impending utilization of tannins for ensuring high-sustainability and better environmental performance.