Effects of radio-frequency-assisted blanching on the polyphenol oxidase, microstructure, physical characteristics, and starch content of potato

The effects of radio-frequency (RF)-assisted blanching and conventional hot water blanching (HWB) on the polyphenol oxidase (PPO), microstructure, physical characteristics, and starch granules in potato were investigated. The residual activity of PPO decreased from 60.47% to 1.35% with increased RF heating temperature (50–90 °C). Moreover, RF achieved a similar level of enzyme inactivation as HWB at lower temperature (70 °C), thereby maintaining the good physical characteristics. With increased temperature from 50 °C to 90 °C, weight loss (1.15%–6.23%) and relative electrolyte leakage (REL) (6.57%–96.96%) increased. Transmission electron micrographs revealed that the increase in REL was due to the gradual degradation of cell membranes and walls. Confocal laser scanning micrographs suggested that RF and HWB treatments changed the cell morphology and gelatinized the starch granules, leading to texture softening. Furthermore, differential scanning calorimetry thermograms showed that ΔH decreased from 2.80 J/g to 0 J/g with increased temperature. All these findings indicated that the change in physical characteristics of potato depended on its microstructure during RF blanching.