Study of FTIR spectroscopy combined with Chemometrics in the characterization of vegetable tannin from Ceriops decandra

The functionality and widespread application of tannins mainly depend upon their chemical structure. Successful characterization of tannin mainly results in whether it is hydrolysable or condensed. In this study, a tannin-enriched plant Ceriops decandra bark hot water extract was conducted UV-Visible spectroscopy and FTIR spectroscopy along with Chemometrics to characterize its tannin class. However, the λmax value at 264.5 nm in UV-Visible spectroscopy and the FTIR peaks at 1616 cm-1, 1516 cm-1, 1450 cm-1, 1215 cm-1, and 1026 cm-1 revealed the presence of tannin. Again, considering this λmax value with two FTIR peaks at 1709 cm-1 and 1315 cm-1 gave an estimation of the existence of hydrolysable tannin. The study of two Chemometrics tools, principal component analysis (PCA) and hierarchical cluster analysis (HCA) of FTIR spectral data combined with four standard tannins such as Mimosa, Quebracho, Chestnut, and Tara, showed a significant dissimilarity of C. decandra tannin to two condensed tannins (Mimosa and Quebracho) along with meaningful concord to two hydrolysable tannins (Chestnut and Tara). Thus, the rapid characterization using multiple analytical methods and multivariate analysis suggests a harmonious outcome for C. decandra bark, containing hydrolysable tannin.