In-situ dielectric analysis on the responses of vegetable cells to freezing treatment

Abstract

Abstract An in-situ dielectric measurement was implemented on garlic clove, onion, taro and Chinese yam cells undertaken slow cooling from 2.0 to -11.0 °C. The double-membrane structure of vegetable cell corresponding to cell membrane and tonoplast was identified by splitting up one overlapping β-relaxation into two independent relaxations, and a double–shell model was applied to analyze the two dielectric relaxations based on interface polarization mechanism. The dielectric relaxation time (τ) of vegetable cells were found to respond sensitively to the freezing treatment. An abrupt shift of τ demonstrated the formation of extracellular ice, and the disappearance of the lower-frequency relaxation at the ice crystallization point was attributed to the frozen damage of cell integrity.