Ultrasonication and thermosonication blanching treatments of carrot at varying frequencies: Effects on peroxidase inactivation mechanisms and quality characterization evaluation

The effects of ultrasonication (US) and thermosonication (TS) blanching at varying frequencies on the carrot peroxidase (POD) inactivation and potential mechanisms were studied. The physicochemical properties were evaluated. Hot water (HW) blanching was used as control. Thermosonication decreased the POD activity to a greater extent, with a dual-frequency of 22/40 kHz showing the most significant effect. The POD-related gene expression was down-regulated by TS, which was contrary to the thermally treated samples. Electron paramagnetic resonance (EPR) spectra revealed that ultrasound-induced radicals from water sonolysis might involve in the POD inactivation. Thermosonication substantially increased the total carotenoid content (TCC). The color analysis showed that thermosonicated samples with a dual-frequency (22/40 kHz) exhibited the maximum values of C* and Delta E, and the minimum value of the whiteness index (WI). The micrographs verified the alterations in TCC and relative electrolyte leakage (REL) of carrot treated by HW, US, and TS.