Dielectric spectroscopy of trigonella foenum-graecum linn. At 9.85 GHz frequency Karhale G. A 1,* and Kalamse G.M 2

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1 18998 Available online at (Elixir International Journal) Nuclear and Radiation Physics Elixir Nuclear & Radiation Phys. 64 (2013) Dielectric sectroscoy of trigonella foenum-graecum linn. At 9.85 GHz frequency Karhale G. A 1,* and Kalamse G.M 2 1 Deartment of Physics, Madhavrao Patil Arts, Commerce and Science College, Palam Dist. Parbhani (M.S.) India. 2 Microwave Research Laboratory, Deartment of Physics, N E S, Science College, Nanded (M.S.) India. ARTICLE INF O Article history: Received: 10 August 2013; Received in revised form: 25 October 2013; Acceted: 31 October 2013; Keywords Dielectric constant, Conductivity, Fenugreek (Trigonellia Foenum- GraecumLinn.). ABSTRACT Values of dielectric constant ( ), dielectric loss ( ), relaxation time ( τ ), conductivity (σ ) and moisture content of ulverized samles of Fenugreek were measured for different acking densities at 9.85 GHz microwave frequency and at different temerature ( 20 C, 35 C and 50 C). Exerimental results on owders of different acking fractions (δ r ) were used to obtain transformation to 100% solid bulk using correlation formulae of Landau- Lifshitz-Looyenga and Bottcher. It is found that, there was fair agreement between the calculated values of dielectric arameters and the values obtained exerimentally for solid bulk. This shows cohesion in the articles of Trigonellia Foenum-Graecum Linn. owder under investigation Elixir All rights reserved. Introduction The dielectric roerties of sicy-food materials and their constituents, describe their interaction with microwave energy [1, 8, 9] which deends on the frequency of electromagnetic field as well as nature of the material (, moisture content, temerature and comosition). Different workers [2, 5] correlated dielectric behavior of bulk materials and their owders. Landau - Lifshitz and Bottcher have exlained useful information to correlate dielectric behavior of bulk materials and their owder forms. The dielectric roerties of corn and wheat kernels, and soya beans were studied by [11] and [1] have reorted dielectric roerties of raeseed and mustard seeds in owder form at various microwave frequencies. During the resent study, dielectric roerties of Fenugreek seeds were determined at various acking fractions and temerature. The effects of temerature and density on the dielectric arameters correlation of dielectric arameter of Fenugreek seeds owder with solid bulk have been described. The results were comared with the values obtained from correlation formulae between owder and bulk derived indeendently by [3, 10]. Fenugreek (Trigonella foenun-graecum Linn.) is the dried rie fruit of an annual herb, native of South-eastern Euroe and West Asia and now cultivated in India. The seeds are small and yellowish brown in colour. It has a leasantly bitter taste and a eculiar odour and flavor of its own. The seeds are roduced as a sice, as a vegetable for human consumtion, as forage for cattle and to some extent, for medicinal uroses. Fenugreek has been used both as a food or food additive as well as in medicine. Fresh tender ods, leaves and shoots which are rich in Iron, Calcium, rotein, vitamin A and C, are eaten as curried vegetable sine ancient time in India. As a sice, fenugreek seeds also add to the nutritive value and flavor of foods [13]. Comosition :- Fenugreek seeds contains, Protein 9.5%, Fat 10.0%, Crude fibers-18.5%, Carbohydrates-42.3%, Calcium- 1.3%, Phoshorus-0.48%, Iron-0.011%, Pottassium- 1.7%, Moisture-6.3% er 100gm. Material and methods:- The dielectric constant ( ) and dielectric loss ( ) were measured by using reflectometeric technique [4, 12, and 14]. Measuring the reflection co-efficient from air dielectric boundary of samle in the microwave X band at 9.85 GHz frequency at 20ºC, 35ºC and 50ºC temerature. The following equations were used to determine the dielectric arameters. Tele: addresses: karhalega@gmail.com 2013 Elixir All rights reserved

2 18999 λ ' = 0 λc 2 λ0 + λd 1 λo = π λ d 2. (1) 2 α d λ d... (2) Where, λo - the wavelength in free sace. λc = 2a is cut-off wavelength of the wave guide. 2a is broader dimension of the rectangular wave guide. αd- is the attenuation introduced by the unit length of the materials. βd = 2π λd is hase shift introduced by the unit length of the dielectric materials, λd = dielectric wavelength in owder. Fig : Microwave X- band set-u for dielectric measurements. In order to determine (λd) accurately, [6] have designed and develoed a dielectric cell to hold samle owder so as to introduce it in the cell conveniently and to exert equal amount of ressure by the lunger on the owder column in the cell. During resent investigation, small quantity of owder was introduced in the cell and the lunger was brought over the owder column. A ressure was allowed to exert by lunger on owder in the dielectric cell. The height of the owder column and the corresonding reflection co-efficient was measured by means of a crystal ick-u in the directional couler. This rocess was reeated at every addition of owder in the cell. The relationshi between reflected ower and height of the owder column was aroximately given by a damed sinusoidal wave. The distance between two adjacent minima s of this curve gave half the dielectric wavelength (λd = 2L). For the determination of dielectric arameters of Fenugreek, three samles of various articles sizes were reared by using sieves of different sizes. For the comarison of correlation formulae between owder and bulk, the acking fractions (δr) were taken as the ratio of density of owder and the density of the finest crushed closely acked article assembly of the samle. The conductivity (σ) and relaxation time ( τ ) were obtained by using following relations: σ = ω 0.. (3)

3 19000 Where, τ = ω '.. (4) ω is angular frequency of measurement ( 9.85 GHz) 0 is ermittivity of vacuum. Result and discussions:- Dielectric constant ( ), and dielectric loss ( in table 1. The values of ( ), and ( simultaneous increase in dielectric constant ( ) and loss factor ( ) along with the values of relative acking fraction (δr ) of Fenugreek are given ) obtained exerimentally for different grain sizes and temeratures showed that, there is ) with increasing values of relative acking fraction (δr ) while decrease in ( ) and ( ) with increasing temerature. This was exected, because with higher values of relative acking fraction (δ r ) the inter article hindrance offered to the diolar motion for a comact medium will be much higher than for less bounded articles. Such observations have been already made by other workers [7] for higher values of acking fraction. An examination of values of relaxation time ( τ ) loss tangent (tan δ) conductivity (σ ) and values of moisture content with relative acking fraction and different temerature revealed that there was increase in σ, τ and (tanδ) with the increasing values of acking fraction (δ r ). There was a systematic decrease in (σ ), (τ ) and (tanδ), moisture ercentage with increasing values of temerature. Such behavior is exected because when olar molecules are very large, the rotatory motion of the molecules is not sufficiently raid for the attainment of equilibrium with the field. The increase in conductivity therefore, suggests that at higher comactions, no micro cracks are develoed in the samle due to high mechanical ressure. The decrease in relaxation time ( ) with increasing temerature may be due to increase in the effective length of diole. In addition, due to increasing temerature, number of collision increase causes increase in energy loss and thereby decreasing relaxation time. Table -2 gives measured and comuted values of dielectric arameters for bulk from owder measurements. The results reorted at δ r =1 are those measured on the finest crushed owder samle acked very closely in a wave guide cell ressing it under a fixed ressure, so as to obtain minimum voids between the articles. Out of three owder samles of different acking fractions, the samles having minimum article size is defined as finest which is about 0-70 µm. In this case, we assumed it as solid bulk for getting correlation between owder and solid bulk. The correlation formulae were used to find other value for δ r >1. The bulk values obtained for ( ) and ( ) are same to the measured values and those calculated from [10] are closer to the values calculated from [3] formulae. The values of acking density increase linearly with the values of dielectric constant, dielectric loss and conductivity increases shown in Figure. There was a simultaneous decrease of dielectric constant, dielectric loss and conductivity with increase in the temerature. Conclusions:- Thus, it was found that exerimentally measured values of ( ) and ( ) at (δr = 1) are similar to those calculated from Landau-Lifshitz-Looyenga formulae. There was a fair agreement between the values obtained exerimentally and calculated theoretically by using Bottcher s formulae. The correlation formulae of Landau-Lifshitz- Looyenga and Bottcher can be used to rovide accurate estimate of ( ' s ) and ( s ) of owder materials at known bulk densities. It may thus redict that, Fenugreek seeds owder is having cohesion in its articles and may serve as a continuous medium.

4 19001 Table -1 Values of dielectric constant ( ' ), dielectric loss ( ), loss tangent (tan δ), relaxation time ( τ ), conductivity (σ ) and moisture ercentage of Fenugreek owder at different temerature and acking fraction (δ r ) Tem C Packing Fraction (δ r ) σ (10-2 ) Moisture (%) ' tanδ τ (.s.) 20 C C C Table -2 Measured and calculated values of dielectric constant ( ' s ), and dielectric loss ( s ) for bulk from owder at different temerature and acking fraction (δ r ) ' s For solid bulk s For solid bulk Tem C Relative Packing fraction (δr) Measured From Bottcher s formula From Landu, et al formula Measured From Bottcher s formula From Landu, et al formula 20 C C C Grahical reresentations of Dielectric arameters: Dielectric constant Dielectric loss Fig.1: Vs Dielectric constant Fig.2 : Vs Dielectric loss

5 19002 Loss tangent Fig.3 : Vs Loss tangent Relaxation time Fig.4 : Vs Relaxation time Conductivity Dielectric constant Temerature Fig.5 : Vs Conductivity Fig.6 : Temerature Vs Dielectric constant Dielectric loss Loss tangent Temerature Temerature Fig.7 : Temerature Vs Dielectric loss Fig.8 : Temerature Vs Loss tangent

6 Relaxation time T e m e r a tu r e Fig.9 : Temerature Vs Relaxation time Conductivity T e m e r a tu r e Fig.10 : Temerature Vs Conductivity References:- 1. Bansal, A. K., Singh, P.J. and Sharma, K. S. (2001) Indian Journal of Pure and Alied Physics 39: Bhatnagar, D., Gandhi, J. M. and Yadav, J. S. (1996) Indian Journal of Physics 70A (4); Bottcher, C. J. F.(1952) Theory of dielectric olarization. Elsevier ublication, Amsterdam. 4. Chelkowski, A. (1980) Dielectric Physics. Elsevier ublication, Amsterdam. 5. Gandhi, J. M. Jangid, R. A., Neeru, Bhatnagar, D. and Jangid, R. A (1996) Indian Journal of Pure and Alied Physics 34; Kalamse, V. G. and Kalamse G. M. (2007) Lab Exeriements.(30-38), Karhale G. A. and Kalamse G. M. (2011) Bioinfolet 8(4): Kraszewski, A. and Nelson, S. O. (1993) Journal of Microwave Power and Electromagnetic Energy 28(3); Kraszewski, A.and Nelson, S. O.(1994) Journal of Agricultural Engineering Research 58; Landau, L.D. and Lifshitz, E. M. (1960) Electrodynamics of continuous media. Pergamon ress, London Nelson, S.O. (1992) IEEE Transaction on Instrumentation and Measurement. 41(1): Peter, H. (1997) Dielectric sectroscoy of olymers. Adam Hilger Ltd, Bristol. 13. Pruthi, J. S. (1979) Sices and Condiments. National Book Trust, New Delhi, Sisodia, M. L. and Raghuvanshi, G. S. (1990) Basic microwave techniques and Laboratory Mannual. Willey Eastern Ltd, New Delhi.