engleski

Adsorption of polyphenols from apples onto β-glucan

Apples are rich in polyphenolic compounds and, since they are available all year round, they are very important source of these bioactive compounds. Numerous studies have shown that for the polyphenol bioactivities, their interactions with other compounds in surroundings such as dietary fibers, proteins and lipids are of great importance. The aim of this work was to study the interactions between apple polyphenols and β-glucan as a soluble dietary fiber, through studying adsorption processes. Polyphenols were extracted from flesh and peel of five old varieties of apples originating from Croatia (Lještarka, Ljetna rebrača, Slavonska srčika, Adamova zvijezda and wild apple) by using ultrasonic assisted extraction. Total polyphenols and total flavonoids were determined by using spectroscopic Folin Ciocalteau method and a method based on flavonoid-aluminum chloride complexation, respectively. The results showed that Slavonska srčika and wild apple were the richest in polyphenols. These apples were chosen for adsorption experiment at a room temperature, for 16 h, at four different concentrations. The parameters of Freundlich, Langmuir and Dubinin-Radushkevich adsorption isotherms were determined. The study showed that apple polyphenols adsorbed onto the surface of β-glucan in the in vitro experiment which implies their possible interactions with dietary fiber in the human organism.

Apples; polyphenols; dietary fiber; adsorption; adsorptions isotherms

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