Harum Manis Mango Dielectric Properties

Based on Maturity

Khairudi Mohd Juni

Electrical Engineering Department

Politeknik Tuanku Syed Sirajuddin

Perlis, Malaysia

Mohd Fareq Abd Malek,Manjur Ahmed,

Cheng Ee Meng

Universiti Malaysia Perlis

Perlis, Malaysia

Abstract— This paper presents Harum Manis mango maturity

characterizations based on dielectric properties. Currently,

Harum Manis maturity is determined by referring to number of

weeks of growth and farmer experience. This paper proposes a

quick and simple microwave measurement technique. An open

ended dielectric probe is used to measure dielectric properties of

Harum Manis mango for frequency range from 500 MHz until 20

GHz. The relationship between dielectric constant and loss factor

as well as week of growth is established. These data contributes to

further research of Harum Manis maturity sensor application.

Keywords- Harum Manis mango; dielectric properties; open

ended probe; maturity

I. INTRODUCTION

Harum Manis Mango (Mangifera Indica Lynn) is special local fruit in Perlis, Malaysia. It has potential to be exported to overseas [1] since it has unique taste and aroma which has high commercial value. However the fruiting season only last for two months, thus rapid maturity classification is needed.

In fruit maturity inspection, Rutpralom et. al [2] used microwave free space measurement on Durian. Zhenfeng Li et. al [3] build maturity index for Mango based on Total Soluble Solids. Abdul Khalid et. al [4] characterize Siamese Mango based on K-Band frequency range.

For measurement, open ended coaxial probe method is being used by [5], [6], [7], [8] and [9] for dielectric properties measurement on fruits, vegetables and liquids. This method is simple and rapid compared to free space measurement method.

In this paper, Harum Manis mago maturity determination will be discussed among immature, harvest, ferment, ripe and rot stages. The relationship of dielectric constant and loss factor with frequency for different stages is developed for analysis.

II. BASIC THEORY

An electromagnetic wave partially transmitted through a material. In the meantime, partial energy of wave will be absorbed by the material and also reflected back. The amount of energy in this mechanism is determined by complex permittivity, ϵr. It can be modeled as follows:

ϵr = ϵ‟ - ϵ” (1)

ϵ‟ refers to dielectric constant which explicate the ability of material in energy storage. Meanwhile ϵ” describes the attenuated and absorbed energy in material.

Harum Manis Mango grows on tree for 13 weeks. Week 13 is the critical time to harvest for optimum maturity. After the harvest, the mangoes will be fermented in a closure for 72 hours. Upon completion of fermentation, the mangoes are on leave on room temperature condition for natural ripening process. Additional 72 hours required for this process. This is to achieve ripe to eat stage for mango. 1 week afterward, it will start to rot.

III. MEASUREMENT

An Agilent E8362B Network Analyzer is connected to Agilent 85070E Dielectric Probe via Hewlett Packard 8120-6192 cable for measurement. The probe calibrated with air, shorting block and water at 25⁰C. Frequency range for dielectric properties measurement is from 500 MHz until 20 GHz.

60 samples (Harum Manis mango) are collected from following maturity stages as per Table 1 below. Each sample measured at 12 different points on mango surface without air gap.

Table 1

Harum Manis mango maturity stages samples and category.

Stages Quantity of

samples (pieces) Category

Immature Week 11 10

On tree Immature Week 12 10

Mature Week 13 10

Ferment 10

Off tree Ripe to eat 10

Rot 10

2011 IEEE International RF and Microwave Conference (RFM 2011), 12th - 14th December 2011, Seremban, Malaysia

978-1-4577-1631-7/$26.00 © 2011 IEEE 19

IV. RESULT AND DISCUSSION

Dielectric constant and loss factor are obtained from the measurements and their measured results are as shown in Figure 1 and Figure 2, respectively. Figure 1 shows the dielectric constant,ϵ‟ and Figure 2 shows the loss factor,ϵ”.

A. Dielectric constant

From Figure 1 above, dielectric constant decrease as frequency increase.

It is clearly displayed that the fruits on tree show different properties compared to fruits off tree. All lines are presented in consecutive order which is immature W11, immature W12, mature W13, ferment, ripe to eat and rot.

Fruit harvesting before or after week 13 need to be avoided as to optimize fruit quality. However, trend lines for week 12 and week 13 are nearly identical.

During ferment, ripe and rot stages, lower dielectric properties observed. These 3 trend lines shows some gap at high frequency.

B. Loss factor

From Figure 2 above, loss factor increase as frequency increases.

In Figure 2, loss factor increase with frequency. The loss factor is low at lower frequency. On higher frequency, higher loss factor observed.

Similarly, all trend lines are in consecutive order except for rotting stage. Non uniform rotting found on the fruit surface.

On tree mango shows higher dielectric constant and loss factor compared to off tree mango.

ACKNOWLEDGMENT

The authors thank Jabatan Pertanian Negeri Perlis for providing Harum Manis mango samples and Politeknik Tuanku Syed Sirajuddin for supporting research activities.

CONCLUSION

Dielectric constant and loss factor observed and compared to various maturity stages of Harum Manis mango based on broad frequency. Data obtained is utilizable for maturity sensor development in terms of simulation and testing. Unique characteristic found between on tree and off tree category. Future development for rapid and reliable large scale harvesting, correct fermentation period and optimum fruit quality grading will be contributed by dielectric properties data.

REFERENCES

[1] Rosidah Musa, Faridah Hassan, Jamaliah Mohd Yusof and Norzaidi

Mohd Daud, “Examining market accessibility of Malaysia‟s Harumanis mango in Japan : challenges and potentials,” Business Strategy Series, vol. 11, pp. 3–12, 2010.

[2] T. Rutpralom, K. Chamnongthai, P. Kumhom, and M. Krairiksh,

“Nondestructive Durian Maturity Determination by Using Microwave

Free Space Measurement,” IEEE Int symp. Circuits and Systems, pp.

1351-1354, 21-24 May 2006.

[3] Li, Z.; Wang, N.; Vijaya Raghavan, G.S.; Vigneault, C. Ripeness and rot evaluation of „Tommy Atkins‟ mango fruit through volatiles detection. J. Food Eng. 2009, 91, 319-324..

[4] M.F. Abdul Khalid, A.S Ramli, N.H. Baba and H. Saad, A Novel Preliminary Study on Microwave Characterization of Siamese Mangoes Ripeness at K-Band. IEEE International RF and Microwave Conference Proceedings. 2008.

[5] Stuart O. Nelson, Wenchuan Guo and Samir Trabelsi, Study of Fruit Permittivity Measurements for Quality Detection. FMTC 2008 – IEEE International Instrumentation and Measurement Technology Conference. 2008.

[6] Stuart O. Nelson, Wenchuan Guo and Samir Trabelsi, Investigation of Dielectric Sensing for Fruit Quality Determination. SAS 2008 – IEEE Sensors Applications Symposium. 2008.

[7] Stuart O. Nelson. Measuring dielectric properties of fresh fruits and vegetables. IEEE Antennas and Propagation Society International Symposium. 2003.

[8] Stuart O. Nelson. Dielectric Spectroscopy for Agricultural Applications. Instrumentation and Measurement Technology Conference. 2004.

[9] Wenchuan Guo, Xinhua Zhu, Yi Liu and hong Zhuang. Sugar and water contents of honey with dielectric property sensing. Journal of Food Engineering 97 (2010), pp. 275-281.

On tree

Off tree

Figure 1. Dielectric constant of Harum Manis mango against frequency at various stages

On tree

Off tree

Figure 2. Loss factor of Harum Manis mango against frequency at various stages

2011 IEEE International RF and Microwave Conference (RFM 2011), 12th - 14th December 2011, Seremban, Malaysia

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