Effect Of Ultrasound Treatment On The Stability Of Blueberry Anthocyanin

Blueberry,as a high-value berry,is a plant with high anthocyanin(Acy)content.The most abundant part of its Acy content is its unique purple peel site.Although blueberry has been widely used in beverages,wine and other food industries,its pomace has not been fully utilized effectively.Therefore,the extraction process of Acy from blueberry pomace is very necessary.Ultrasound as a simple and efficient,cost-effective extraction method has been widely used in the extraction of natural products,which have been reported in the literature that ultrasonic treatment can cause the degradation of phenolic acids,polysaccharides etc.,However,the effect of sonication on the stability of Acy is also reported slightly.Therefore,in this study,five kinds of Acy and blueberry pomace Acy were used to study the influence of ultrasound on the stability of Acy in ultrasonic extraction simulation system and real-world system,which could be a theoretical reference for the application of ultrasound-assisted extraction Acy from blueberry pomace.The main results are as follows:1.Results indicated that a higher ultrasound power density induced a higher Acy degradation.While the degradation rate showed a decrease trend with an increase in temperature,which suggest a negative correlation between cavitation intensity and temperature.The degradation rate of five Acys was minimal affected in 70%ethanol aqueous solution and showed a peak pattern in the range of pH 1?5(peak value was observed in pH=3).2.The degradation kinetics of Delphinidin(Dp)-3-glucose by ultrasonic treatment fitted well to first-order reaction kinetic,while Pelargonidin(Pg),Malvidin(Mv),Peonidin(Pn),Cyanidin(Cy)-3-glu were consistent with zero-order reaction kinetic.Degradation products were further tentatively identified by HPLC-ESI.Anthocyanone A was characterized as the common degradation products of four Acys(Pg?Mv?Pn?Cy-3-glu)under ultrasound condition,which were not detected in degradation products of Dp-3-glu.In addition,kaempferol,quercetin,syringic acid,ferulic acid and 2,6-dimethoxyphenol were found simultaneously under the ultrasound treatment.3.Malvacein-3-galactoside is the most abundant in blueberry Acys(Shengzhou,Zhejiang Province,China),while Acys with delphinidin aglycone accounted for the largest proportion.The total Acys and single Acy content extracted from blueberry pomace increased first and then decreased with increasing ultrasonic time(0?50min).The blueberry pomace total Acys reached the maximum12.49 mg/g(DW)under ultrasonic conditions in the pure methanol extraction system,40?,30min,while the blueberry pomace single Acy in 70%ethanol aqueous extraction system,40?,40min,a maximum of 3.57 mg/g(DW);4.The total Acys and single Acy extraction abilities of blueberry pomace at three temperature were as follow:10<25<40?;At the same time,it was found that the peak of total Acys and single Acy congtent extracted by ultrasound in different solvents was significantly higher than that of the control experiment.The optimum extraction solvent for total Acys was pure methanol,followed by 70%methanol aqueous,while the single Acy 70%ethanol aqueous,followed by pure methanol;Three factors interaction of solvent,temperature,time had no significant effect(p>0.05)on the blueberry total Acys extraction volume,but significant effect on single Acys extraction(p<0.05).However,two factors interaction of solvent,temperature,time had a significant effect on the extraction of total Acys and single Acy in blueberry pomace(p<0.05).