engleski

Adsorption of gallic acid onto barley β-glucan

Polyphenols are a group of secondary plant metabolites, usually present in human nutrition with reported potentially positive bioactivities. These compounds can interact with dietary fibers such as -glucans which can affect their bioactivities. Gallic acid belongs to polyphenolic group, subclass of phenolic acids. The aim of this work was to study interactions between gallic acid and β-glucan from barley trough investigating adsorption processes. Adsorption was conducted on three pH values (1.5, 5.5 and 10, temperature 25 °C) for 16 hours until adsorption reached equilibrium. The amount of gallic acid adsorbed per g of barley -glucan (qe, mol/g) was calculated. The qe values and the amount of un- adsorbed gallic acid at equilibrium (ce) were modelled with nonlinear adsorption isotherm equations (Langmuir, Dubinin-Radushkevich and Hill). At pH 1.5 and 5.5, adsorption was similar while at pH 10 gallic acid adsorbed in a higher amount. Experimental results were fitted well with all three isotherm models, gave similar values for qe and helped us to suggest physical bonds (like H bonds) between gallic acid and barley -glucan.

β-glucan ; gallic acid ; adsorption

nije evidentirano