Effects Of Ultrasonic Wave Treatment On Stabilities Of Pelargonidin-3-glucoside From Strawberries

In this research,Pelargonidin-3-glucoside(Pg-3-glu)from strawberry extracts were used as materials.The effects of ultrasonic waves on Pg-3-glu stabilities and corresponding changes of UV-Visual spectrum and antioxidant activity were investigated.Further,the influence factors and the relation between hydroxyl radical concentration induced by ultrasonic waves treatment process and anthocyanin degradation was analyzed.Moreover the kinetics,mechanisms and pathways of anthocyanin degradation by Ultrasonic waves were discussed.The main results and conclusions are made as follows.:(1)In this study,four kinds of anthocyanins were separated from the strawberry extracts,of which the largest content is pelargonidin-3-glucoside(Pg-3-glu).Purity of Pg-3-glu is 77.46%measured at 280nmby HPLC.(2)After ultrasonic treatment,the basic spectral characteristics of Pg-3-glu were not significantly changed.The maximum absorption wavelength is 280nm and 501nm remains.However,with the degradation of anthocyanins,Pg-3-glu intensity of the peak at 501 nm was significantly decreased.The degradation kinetics of Pg-3-glu by Ultrasonic waves was well fitted to a first-order reaction.And the degradation rate constant of Pg-3-glu is much larger than the rate of thermal degradation.With the total ultrasonic energy increasing,concentration of anthocyanin significantly decreased.And there is good correlation between the total ultrasonic energy and Pg-3-glu degradation(R2=0.9432).(3)With time and power of the ultrasonic treatment increasing,hydroxyl radical concentration was increased and the antioxidant activity of the system was reduced.There was a good linear correlation between hydroxyl radical concentration and degradation of anthocyanins(R2=0.8795).By inference,the main principle of ultrasonic degradation of anthocyanins was cavitation.Cavitation cleavage water molecules to produce hydroxyl radicals(·OH).Then · OH attack anthocyanin molecules,resulting in degradation of anthocyanins.