Effects Comparison of Ultrasound-assisted Adsorption of Anthocyanins from Blueberry Pomace Extracts by Different Adsorbents

Ultrasonic wave(20 kHz)was used to adsorb anthocyanins from blueberry pomace by four different materials(macroporous resin XAD-7HP,Saccharomyces cerevisiae,activated carbon,bentonite). The adsorption effects of different adsorbents on anthocyanin assisted by water bath oscillation and ultrasonic were compared. The adsorption kinetics process was studied and the kinetic model was fitted. Infrared spectroscopy was used to analyze the structural changes of adsorbents before and after ultrasonic-assisted adsorption to find out the functional groups that might play a role in the adsorption process. The results showed that the adsorption capacity of anthocyanin by the four adsorbents was significantly higher than that by water bath oscillation(P<0.05). The ranking of adsorption capacity was macroporous resin XAD-7HP>activated carbon>bentonite>Saccharomyces cerevisiae. Under the action of ultrasound,the adsorption capacity of anthocyanin by Saccharomyces cerevisiae increased by 19.56%,and the other adsorbents were bentonite,activated carbon and resin with the increasing of 16.48%,11.90% and 8.62%,respectively. Compared with the first-order kinetic model,the Lagergren second-order kinetic model could better fit the adsorption process of anthocyanin by the four adsorbents. Fourier transform infrared spectroscopy showed that the phenolic hydroxyl group on the surface of macroporous resin shifted during the adsorption process,which might be used to form hydrogen bond.-COOH and-OH in Saccharomyces cerevisiae were involved in the adsorption process,and the hydrogen bond shift might occur,the polysaccharides and amide groups also played a role. The adsorption process of anthocyanin by activated carbon was affected by C=C and C-O,and O-H deformation vibration or-CH₂ deformation vibration might also be involved. The deformation and bending vibration of Si-O occurred in the adsorption process of bentonite,and the absorption peak of original -OH shifted,which indicated that the successful adsorption of anthocyanin by bentonite might be due to the displacement of hydrogen bond.