CHARACTERIZATION OF OSMOTIC DEHYDRATION AND SWELLING OF APPLE TISSUES BY BIOELECTRICAL IMPEDANCE SPECTROSCOPY

Abstract

The electrical impedance of apple strip samples immersed in osmotic medium was investigated to characterize a dehydration process with sucrose solution and a swelling (hydration) process with deionized distilled water. The impedance measured at frequencies of 10 Hz to 100 kHz could be fitted well by an electrical equivalent model ‘Hayden model’. Symplasmic (intracellular) resistance and apoplasmic (extracellular) resistance assumed in the model showed a specific increase or decrease which corresponded to a dehydration or swelling (hydration) process respectively. Consequently, the changes in the resistances were suggested to be caused by an increase or a decrease in moisture content in extracellular and intracellular volumes. Furthermore, the time variation of the resistance values could be represented approximately by a first-order response equation. Therefore, it was concluded that bioelectrical impedance spectroscopy (BIS) was applicable to the simple detection of dehydration and swelling and that it was a helpful and effective method to monitor dehydration and swelling processes nondestructively and continuously.

Keywords:

• BIS
• Hayden model
• Intra- and extra-cellular resistance
• Response equation

ACKNOWLEDGMENT

This study was supported in part by a Grant-in-Aid for Scientific Research (A, No. 10356009) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.