Impact of intermittent and continuous electric fields on peroxidase inactivation in orange juice: An experimental and molecular dynamics analysis

Abstract

This study examines the efficacy of moderate electric fields (MEFs) on peroxidase (POD) inactivation in freshly squeezed orange juice. Inactivation kinetics was studied with two types of electric field application modes: intermittent and continuous, and compared that with thermal-only (no field) treatments at different temperatures ≤80 °C. The kinetic studies showed a significant increase in the inactivation rate constant (∼147%, P ≤ 0.05) with increasing temperature, from 72 to 80 °C, in the continuous MEF treatments, whereas the increase was minor (∼47%, P > 0.05) in the no field treatments. In molecular dynamics analysis, periodic unfolding and refolding of the POD molecule were observed in the intermittent electrical treatments. Noticeably, the continuous electrical treatments caused a greater degree of unfolding, exhibiting marked conformational and secondary structure changes, and increasing (P ≤ 0.05) salt bridge counts. These findings are relevant for inactivating enzymes at mild temperatures.