Abstract

The paper presents a necessarily brief review of tannins and tanning, covering the following topics. Tannins: Occurrence of tannins in nature, reason for existence and relationship to plant metabolism. Chemical types- classification into condensed tannins, ellagitannins and gallotannins. Tanning: Tannin/protein interaction – electrovalent and hydrogen bonds and hydrophobic interaction. Equilibrium between tannin and protein – tanning as a polar absorption. Principles of vegetable tanning. Importance of acids, salts and other osmotic considerations.