engleski

Beta- glucan from barley as an adsorbent of quercetin derivatives

Β-glucan is a dietary fiber present in cereals like barley and oats. It has shown many positive bioactivities in the human organism. One of positive effects of dietary fibers in general, and -glucan in particular, is their interaction with polyphenols, a group of secondary plant metabolites, commonly present in human nutrition. Namely, -glucan has the potential to bind polyphenols, protect them from the degradation, and transfer them to the lower parts of the digestive tract, which may affect bioactivities of polyphenols. Interactions between polyphenols and -glucan can be analysed by studying the adsorption process in which -glucan serves as an adsorbent. The aim of this work was to investigate the adsorption of a quercetin derivatives (quercetin-3-glucoside, quercetin-3-galactoside and quercetin-3-rhamnoside) as a group of polyphenols, onto β-glucan from barley as an adsorbent, at three different temperatures: 25 ° C, 37 ° C and 45 ° C. The concentration of nonadsorbed derivatives of quercetin after equilibration was determined by the spectrophotometric Folin-Ciocalteu method (cₑ, mol l-1), and the adsorption capacity (qₑ, mol g-1) was calculated. Experimental data (cₑ and qₑ) were modeled with the equations of three different adsorption isotherms (Freundlich, Langmuir, and Dubini-Radushkevich) by using nonlinear regression. It has been shown that -glucan can be an efficient adsorbent of quercetin derivatives, and that the temperature and glycosylation affect adsorption process. Namely, quercetin derivatives showed different adsorption capacity at different temperatures. Further studies about the influence of other parameters on adsorption of quercetin derivatives (pH value, ionic strength, kinetic studies) are required.

beta-glucan ; barley ; polyphenols ; adsorption

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