A solution spectroscopy study of tea polyphenol and cellulose: effect of surfactants

Abstract

Catechin, a bioflavonoid, found in green tea leaves has various applications in the food and pharmaceutical industries. However, little has been studied about its behavior with fabric-type materials especially in the presence of surfactants. Studying this lays the footstone for understanding the cause of tea stains on fabrics, which is a nuisance as they do not wash off easily or completely even after washing with a detergent, especially if the stain is aged. The intriguing question that needs to be addressed is what are the possible molecular interactions occurring between the polyphenols and the cellulosic materials, especially in the presence of a surfactant. To find answers, we studied a model system representing a cotton fabric and investigated the effect of a specific tea polyphenol on it under various conditions like pH, time and the presence of surfactants. Experiments were performed using fluorimetry, UV-Visible spectroscopy, FTIR and ¹H-NMR spectroscopic techniques to decipher the molecular interactions. The results showed enhanced oxidation of the polyphenol at elevated pH aggravated by surfactants in the presence of a cellulosic substrate. Furthermore, we showed that adding reducing agents in the medium hinders polyphenol oxidation and prevents staining to considerable extent.