Effect of heating temperature on cell impedance properties and water distribution in apple tissue

China has a large amount of apple production and a wide planting area. To increase the yield of juice, it is necessary for juice processing industry to pretreat apples. A traditional method of pretreatment is to heat the apples to make the cell wall broken, change the inter-cellular adhesion force, enhance the mobility of water in apple tissues and soften the cells. Up to now, the traditional chemical methods and the modern techniques, such as microtechnic and image processing techniques, have been adopted to analyze the influence of temperature on fruit tissues. Electrical impedance spectroscopy (EIS) is a fast developing method in analyzing materials' characteristics. When the currents with different frequencies flow through the biological tissue, the cytomembrane, the extracellular and intracellular fluid would show various electrical properties. Therefore, EIS has the potential to be used for detecting the change of apple cell microstructure during the heating. EIS can be used to determine the thermal dam