Analysis of Electrical Properties of mangosteen pulp and detection of its Quality using X-frequency sensor system

Abstract

This paper introduces the electrical properties measurement of translucent and normal flesh mangosteens in the frequency range 10-11 GHz. The measured data were then used to model the mangosteen for free-space technique measurement simulation. The proposed system comprises a transmitting and a receiving antenna, a high-frequency dielectric resonator oscillator, a frequency mixer, a stepping motor to rotate the mangosteen during measurement, a power detector, an analog-to-digital converter, and a microcontroller. The concept of this system is to transmit signal to mangosteen and receive the reflected signal from mangosteen at varied angle 0 to 360 degrees around it in azimuth plane. The reflected signal is then mixed with a local oscillator to produce intermediate frequency for being the reference level to detect translucent flesh within mangosteen. The measured dielectric constant and dielectric loss factor at the frequency of 10.525 GHz of the translucent flesh were 45.08 and 28.32, respectively, while they were 40.43 and 25.89, respectively for the ordinary flesh. The prototype system was validated by measuring 54 mangosteen samples. The measured data were then normalized to reduce the effect of mangosteen shape. The calculated standard deviation was used for decision-making in classification process which the average standard deviations of translucent and normal flesh were 0.11 and 0.03, respectively. The threshold level for mangosteen classification was 0.085. The classification accuracy achieved 84.4%. Thus, the sensor system is efficient and suitable for the application.