Abstract: In order to better understand anthocyanin (Acy) extraction with ultrasound treatment, the stability of five common Acy compounds was analyzed under different ultrasound conditions (power density, temperature, solvent and pH) in a model system and their degradation kinetics were obtained by a trial-and-error approach. Their degradation products were investigated by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS). Results indicated that the degradation efficiency of Acy under ultrasound treatment declined with increasing temperature. All five Acys had the lowest degradation efficiency in 70% ethanol. The degradation efficiency of Acy decreased initially and then increased with pH in the range of 1-5. The degradation of delphinidin-3-glucose (Dp-3-glu) under ultrasonic treatment was fitted well to the first-order reaction kinetics, while pelargonidin (Pg)-3-glu, malvidin (Mv)-3-glu, peonidin (Pn)-3-glu, and cyanidin (Cy)-3-glu were consistent with the zero-order reaction kinetics. In addition to anthocyanone A, kaempferol, quercetin, syringic acid, ferulic acid and 2,6-dimethoxyphenol were detected in the degradation products of all Pg-3-glu, Mv-3-glu, Pn-3-glu and Cy-3-glu.

Key words: anthocyanin, ultrasound, stability, degradation reaction kinetics, degradation products