Analysis of energy response of anthocyanin in berry puree under microwave heating

Abstract

To elucidate the anthocyanin stability in berry puree undergoing dehydration processing through microwave heating, the energy response properties of anthocyanins were investigated through the difference of activation energy and dielectric properties between anthocyanin and water molecules. The results exhibited greater molecular weights and stronger hydrogen bonding interactions of anthocyanins molecule delayed its dielectric polarization under microwave. However, the anthocyanin demonstrated greater sensitivity to microwave energy compared to other macromolecules such as fructose, glucose, and pectin in berry puree. The release and degradation of anthocyanins have positive correlation with moisture content and temperature, respectively. Microwave promotes anthocyanin release at a relatively lower temperature through breaking the intermolecular and intramolecular interactions of components due to the lower microwave intensity or the shorter exposure duration causing less structural plasmolysis. For the microwave heating berry puree, the energy response difference in activation energy of water evaporation lower than that of anthocyanin degradation, resulting the selective energy absorption of polar molecules. The higher activation energy required for anthocyanin degradation enhanced greater stability, allowing continued anthocyanins release up to 80.00 °C under microwave heating. This study provided a guidance for the optimal technology of microwave energy input for the berry processing to enhance the retention of heat-sensitive components.