engleski

Chemical structure of phenolic acids during the adsorption process onto β-glucan

Polyphenols are large groups of secondary plant metabolites. They showed many bioactivities like interactions with dietary fibre. These interactions can influence their accessibility for absorption (bioaccessibility) and their amount that is being absorbed (bioavailability). Interactions between polyphenols and dietary fibre like β-glucan can be studied through adsorption process. Many factors can have influence on adsorption process like chemical structures of polyphenols. The aim of this study was to investigate the adsorption between phenolic acids (gallic acid, p-coumaric acid, caffeic acid and chlorogenic acid) and β-glucan and to see how chemical structure influenced the adsorption process. Adsorption was carried out at 25 °C and pH 5.5 for 16 hours. The non-linear Dubinin-Radushkevich model was applied in order to analyze the data and to obtain the informations about chemical bounds between phenolic acid and β-glucan. The results showed that hydroxybenzoic acid (gallic acid) showed the higher adsorption capacity than hydroxycinnamic acids (caffeic, p-coumaric and chlorogenic acid). This could be related to the chemical structure of polyphenols. The order of adsorption capacity can be connected with the chemical structure of polyphenols. The higher number of hydroxyl groups can favor the adsorption of phenolic acids onto β-glucan. Gallic acid has the highest number of hydroxyl groups attached on the ring of all phenolic acids and showed the highest adsorption capacity, followed by caffeic acid and p-coumaric acid. The chlorogenic acid showed the lowest adsorption capacity. In this case the esterification between caffeic acid and quinic acid which are the building blocks of chlorogenic acid could lowered the adsorption capacity on β- glucan. From the Dubinin-Radushkevich model the bonds between phenolic acids and β-glucan could be physical bonds like hydrogen bonds and Van der Waals forces.

adsorption, chemical structure, polyphenols, β-glucan

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