1. Tannins: origin and properties

The history of tannin chemistry began in the mid-17th century, when the Italian chemist Giovannetti studied the interactions between iron solutions and the substances then known as astringents. In 1772, researchers at the University of Dijon were the first to identify the presence of an acid in these compounds; this acid was subsequently isolated by Scheele and found to be gallic acid. On the basis of experiments by Deyeux and Bartholdi, continued by Proust in the late 18th and early 19th centuries, tannins were officially recognized as a discrete group of molecules that differ according to their gallic acid content. The boom in the tannin extraction industry began around 1850 in Lyon, where tannin was used as an iron tannate to dye silk for women's blouses black