Effects of mild heating treatment on texture degradation and peroxidase inactivation of carrot under pasteurization conditions

Mild heating is an attractive method to improve the texture of vegetables. In this study, we applied mild heating treatment with various temperatures and durations to carrot roots, and we evaluated the effects on texture degradation and peroxidase inactivation during subsequent heating treatment to mimic pasteurization or blanching. Mild heating, especially at 60 °C for 60 min, inhibited softening during subsequent heating treatment. Activation energy required for the softening was 153.3 and 185.2 kJ mol ⁻¹ for untreated and mild-heated (60 °C, 60 min) samples, respectively. To evaluate tissue condition, we applied electrical impedance analysis. During mild heating, the cell membranes were damaged and electrolyte flow was activated. We assumed that mild heating increased calcium levels in the cell wall, leading to the crosslinking of pectin, thus improving the cell structure of carrot samples. Although mild heating at 60 °C did not inactivate all of the peroxidase, mild heating at 70 °C inactivated the heat-resistant fraction of peroxidases. The results of this study can contribute to designing processes for improving the texture of processed vegetables.