Polyphenols and β-glucan interactions through linear adsorption models

The aim of this work was to obtain information about interactions between polyphenols and β-glucan through linear adsorption equilibrium models. Polyphenolic compounds can interact with various food ingredients such as carbohydrates, proteins and lipids and these interactions can affect polyphenol bioactivities. Interactions can be studied through the adsorption process at a constant temperature and adsorption isotherms can be obtained. In this work the interactions between polyphenols like gallic acid, cyanidin-3-galactoside and cyanidin-3-glucoside and β-glucan as a natural dietary fiber were studied through the Freundlich's, Langmuir's, Dubinin-Radushkevich's, Tempkin's and Hill's models. The adsorption was carried out through model solutions of different concentrations of polyphenols and βglucan for 16 hours at 25 °C. After the adsorption, the unadsorbed polyphenols were separated from the adsorbed ones by ultrafiltration. Concentrations of the unadsorbed polyphenols were determined by the spectrophotometric Folin-Ciocalteu method for gallic acid, and the pH differential method for cyanidin-3-galactoside and cyanidin-3-glucoside. The results of adsorption isotherm parameters showed that adsorption between all polyphenols and β-glucan were physical, and all interactions were favorized. Gallic acid showed the highest maximum adsorption capacity onto β-glucan. This study showed that information about interactions between polyphenols and dietary fibers can be obtained through the linear adsorption equilibrium isotherms.