ELECTRICAL IMPEDANCE SPECTROSCOPY AS A POSSIBLE NONDESTRUCTIVE METHOD IN QUALITY ASSESSMENT

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ELECTRICAL IMPEDANCE SPECTROSCOPYAS A POSSIBLE
NONDESTRUCTIVE METHODIN QUALITY ASSESSMENT

• Eszter Vozáry
• Corvinus University of Budapest, Department of
  Physics and Control

8TH INTERNATIONAL CONFERENCE OF FOOD
PHYSICISTSPHYSICS AND PHYSICAL CHEMISTRY OF
FOOD24-27 September, 2008 in Plovdiv, BULGARIA
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INTRODUCTION
Food quality
Physical properties optical mechanical electric
al
Objective characteristics
Chemical properties moisture content sugar
content acidity
Subjective characteristics
Colour Taste smell
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Main goal of research
easy, quick measurement
and
Physical properties
Non destructive
connection mathematical function
Subjective properties Chemical properties
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Electrical impedance
Electrical impedance spectrum
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Impedance spectrum of various plant tissue
compartment
Bound water macromolecules
Ions, electrodes
Cell membrane
Free water
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Our earlier results on apple flesh without skin
destructive methods
Approach of measured spectra with various
electrical model circuits
Some impedance parameters changing during
storage of fruits
Some impedance parameters characterizing
mechanical bruise of apple flesh -
characterizing the moisture content of plant
tissue
AIM OF THIS STUDY
Measurement of apple flesh impedance on whole
apple with skin
With non destructive method
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MATERIAL AND METHOD
Electrodes in the equatorial plane of apple
Gala apple
Electrodes
WPI Ag/AgCl electrodes
Fiab Spa ECG electrodes
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Impedance measurement
4284A LCR meter HP Frequency range 100 Hz 1
MHz Measuring voltage 1 V Ag/AgCl electrodes (WPI
and Fiab Spa) Electrodes conducting gel
Open-short correction
Apple - with skin - without skin
Approach of measured spectra
Least square method for complex number with MatLab
Apple skin
Apple flesh 1
Apple flesh 2
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CONCLUSION
It is possible to determine the impedance
spectrum of apple flesh from spectrum measured on
whole apple with skin
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Thank you for your attention!