SCREENING OF POTENTIAL TANNIN YIELDING TREE SPECIES FOR INDUSTRIAL AND COMMERCIAL APPLICATIONS

Abstract

The tannins are naturally occurring polyphenolic compounds valued for their antioxidant, antimicrobial, astringent, and protein-binding properties, with applications in the leather, pharmaceutical, food, cosmetic, and wood-based industries. The study aimed to estimate the tannin content of selected tree species and identify promising natural sources for commercial exploitation. A literature survey covering 100 tannin-producing species from more than 30 botanical families revealed that the Fabaceae family was the most dominant. Condensed tannins were the predominant type, while bark was the principal plant part used for tannin extraction. Ten tree species were selected for experimental evaluation, and tannin content was determined using the Folin - Ciocalteu colorimetric method following solvent extraction with 70% aqueous acetone. The results showed significant variation in tannin content among the species, ranging from 7.0% to 37.5%. Eucalyptus camaldulensis recorded the highest tannin content (37.5%), followed by Acacia nilotica (36.0%) and Butea monosperma (35.5%). Moderate tannin levels were observed in Terminalia arjuna, Casuarina equisetifolia, Cassia fistula, Emblica officinalis, Pterocarpus santalinus, and Mangifera indica, while Ficus religiosa exhibited the lowest tannin content (7.0%). The study identified Eucalyptus camaldulensis, Acacia nilotica and Butea monosperma as promising tannin-rich species with potential for sustainable extraction and commercial applications in leather processing, wood adhesives, pharmaceuticals, natural antioxidants, and other value-added industrial products.