Dielectric Properties of Vegetables and Fruits as a Function of Temperature, Ash, and Moisture Content

Sipahioglu, O.; Barringer, Sheryl A.

doi:10.1111/j.1365-2621.2003.tb14145.x

Cited by 137 publications

(97 citation statements)

References 17 publications

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“…The heat source depends on the electromagnetic field frequency of the microwave oven, the absolute dielectric constant e, the dielectric loss factor of the material ε", and the electric field strength inside the material e. The electromagnetic field frequency of the microwave oven used in the experimental study is f = 2450 MHz and the absolute dielectric constant is ε o = 8.854 × 10 -12 F/m. Using the data available in the literature, Sipahioglu and Barringer (2003) proposed the following equation for the dielectric loss factor of vegetables and fruits as a function of temperature, ash content and moisture content: ε" = 33.41 -0.4415T + 0.001400T 2 -0.1746m + + 1.438a + 0.001578mT +0.2289aT (11) where: T -temperature (°C) m -wet basis moisture content (%) a -wet basis ash content (%) This equation was adapted to this study. Using the method defined in the literature (Ahaye 2010; Buntaran et al 2010;Purkayastha & Mahanta 2011), the wet basis ash content for the tomatoes used in this study was obtained as 0.40% after 41 ± 0.5 g samples were burned in a muffle furnace (Nüve MF120; Nüve, Ankara, Turkey) at 550°C during 4 h until it became charcoal.…”

Section: Resultsmentioning

confidence: 99%

Microwave drying behaviour of tomato slices

Çelen¹,

Kahveci²

2013

Czech J. Food Sci.

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AbstractÇelen S., Kahveci K. (2013): Microwave drying behaviour of tomato slices. Czech J. Food Sci., 31: 132-138.The microwave drying behaviour of tomato slices was investigated experimentally to determine the effects of microwave power on the drying rate, energy consumption, and dried product quality in terms of colour, and a theoretical model was proposed to define the drying curves of tomato slices. The experiments performed with the microwave power of 90, 180, 360, and 600 W indicate that the drying time and the energy consumption decreased considerably with an increase in microwave power. The experiments also revealed that the drying rate shows first an increase and then a decrease during drying, and that the colour quality of the product deteriorates significantly with the increase of the microwave power. A theoretical model was developed using the solution of energy equation considering the microwave power as an internal heat source. The electric field strength inside the material was assumed to be dependent on the moisture content and the constants emerging from this assumption were obtained by minimising the sum of squared differences between the theoretical results and experimental data obtained for various drying conditions. The results show that the values proposed for the constants provide a good agreement between the theoretical and experimental drying behaviour.

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Section: Resultsmentioning

confidence: 99%

Microwave drying behaviour of tomato slices

Çelen¹,

Kahveci²

2013

Czech J. Food Sci.

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“…A lot of work has been done for studying the electrical and dielectric properties of various food items and food ingredients at microwave frequencies by Sipahioglu and Barringer [7], Sipahioglu et al [8], Soltani et al [9], Sharma and Prasad [10], and many others, but there is no significant amount of work on the study of these properties for tropical fruits at very low frequency levels (0.001 MHz to 10 MHz). Li et al [11] measured moisture content of cookies using dielectric spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Thermal, Structural, and Physical Properties of Freeze Dried Tropical Fruit Powder

Athmaselvi

Kumar²,

Balasubramanian³

et al. 2014

Journal of Food Processing

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This study evaluates the physical properties of freeze dried tropical (guava, sapota, and papaya) fruit powders. Thermal stability and weight loss were evaluated using TGA-DSC and IR, which showed pectin as the main solid constituent. LCR meter measured electrical conductivity, dielectric constant, and dielectric loss factor. Functional groups assessed by FTIR showed presence of chlorides, and O-H and N-H bonds in guava, chloride and C-H bond in papaya, and chlorides, and C=O and C-H bonds in sapota. Particle size and type of starch were evaluated by X-ray diffraction and microstructure through scanning electronic microscopy. A semicrystalline profile and average particle size of the fruit powders were evidenced by X-ray diffraction and lamellar/spherical morphologies by SEM. Presence of A-type starch was observed in all three fruits. Dependence of electric and dielectric properties on frequency and temperature was observed.

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“…5). [18] 1065.5 40Bx [18] 1065.5 60Bx [18] k 0.595 [19] 0.514 20Bx [18] 0.506 40Bx [18] 0.500 60Bx [18] C p 3600 [20] 3125 [21] 71.06 − 0.052T − 3 10 −4 T 2 [22] 67.3 [23] 20.95 − 0.25T + 1.4 10 −3 T 2 [22] 13.28 20Bx [23] 30 40Bx [23] 23 60Bx [23] x I 0.015 Table 3 -Thermal, transport and electromagnetic properties of food for model simulation.…”

Section: Process Simulationmentioning

confidence: 99%

Numerical solution of coupled mass and energy balances during osmotic microwave dehydration

Arballo¹,

Campañone²,

Mascheroni³

2012

Comput. Appl. Math.

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Abstract. The mass and energy transfer during osmotic microwave drying (OD-MWD) process was studied theoretically by modeling and numerical simulation. With the aim to describe the transport phenomena that occurs during the combined dehydration process, the mass and energy microscopic balances were solved. An osmotic-diffusional model was used for osmotic dehydration (OD). On the other hand, the microwave drying (MWD) was modeled solving the mass and heat balances, using properties as function of temperature, moisture and soluble solids content. The obtained balances form highly coupled non-linear differential equations that were solved applying numerical methods. For osmotic dehydration, the mass balances formed coupled ordinary differential equations that were solved using the Fourth-order Runge Kutta method. In the case of microwave drying, the balances constituted partial differential equations, which were solved through Crank-Nicolson implicit finite differences method. The numerical methods were coded in Matlab 7.2 (Mathworks, Natick, MA). The developed mathematical model allows predict the temperature and moisture evolution through the combined dehydration process.Mathematical subject classification: Primary: 06B10; Secondary: 06D05.

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Dielectric Properties of Vegetables and Fruits as a Function of Temperature, Ash, and Moisture Content

Cited by 137 publications

References 17 publications

Microwave drying behaviour of tomato slices

Microwave drying behaviour of tomato slices

Thermal, Structural, and Physical Properties of Freeze Dried Tropical Fruit Powder

Numerical solution of coupled mass and energy balances during osmotic microwave dehydration

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