Effect of Microwave on Changes of Gallic Acid and Resveratrol in a Model Extraction Solution

Abstract

Microwave processing techniques have been extensively used in the food industry due to its significant reduction in time and energy consumption, but its effect on the potential degradation of the extracted target compounds cannot be ignored. In this paper, experiments were carried out to establish a model system of closed magnetic stirring and controlled temperature cooling microwave irradiation (CMCC-MI system); the model extraction solutions were constructed with the standards gallic acid and resveratrol as target compounds to be extracted; its type of free radicals were detected during microwave irradiation extraction, and its changes were monitored under different microwave extraction conditions, namely, solvent types, organic extractant concentrations, microwave irradiation power, extraction temperature, and extraction time, in order to understand the effect of microwave irradiation and provide an objective evaluation polyphenols under different microwave extraction conditions. The degradation and fragment ion peaks of gallic acid and resveratrol owing to hydroxyl free radicals imply that the extraction yield should not be over-focused in actual extraction applications of microwave irradiation; more attention should be paid to the potential degradation of the extracted target compounds induced by microwave irradiation.