Ultrasonic Degradation Kinetics and Isomerization of 3- and 4-O-Caffeoylquinic Acid at Various Ph: The Protective Effects of Ascorbic Acid and Epigallocatechin Gallate on Their Stability

Abstract

Caffeoylquinic acids have been found in many plant species with various biological and pharmacological activities. 3- O -caffeoylquinic acid and 4- O -caffeoylquinic acid are two isomers of caffeoylquinic acids, which may be degraded in processing. The present paper found that the stability of 3- and 4- O -caffeoylquinic acid had decreased with the increasing solution alkalinity , while 3- O -caffeoylquinic acid was more stable than 4- O -caffeoylquinic acid at the same condition. 3- and 4- O -caffeoylquinic acid were converted more to each other than to 5- O -caffeoylquinic acid. Additionally, ultrasonic effects on the degradation and isomerization of 3- and 4- O -caffeoylquinic acid at different pH were studied. Ultrasound facilitated the degradation and isomerization of these compounds. The degradation kinetics were described by the Weibull equation. The protective effect of ascorbic acid and epigallocatechin gallate were also explored. Ascorbic acid and epigallocatechin gallate could abate the degradation of 3- and 4- O -caffeoylquinic acid under certain conditions.