Dielectric heating as a potential post-harvest treatment of disinfesting mangoes, Part I: Relation between dielectric properties and ripening

Sosa‐Morales, María Elena; Tiwari, Garima; Wang, S.; Tang, Juming; García, H.S.; López‐Malo, Aurelio

doi:10.1016/j.biosystemseng.2009.02.015

Cited by 64 publications

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References 22 publications

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“…In general dielectric constant of fruits and vegetables increases with temperature, whereas loss factor may either increase or decrease depending on the operating frequency (Calay et al 1995). generally increased with increasing temperature (Nelson 2003;Sosa-Moralesa et al 2009) and dielectric constant increased with temperature at lower frequencies, but decreased with temperature at the higher frequencies and, temperature dependence of dielectric constant was minimal in the frequency range between 0.01 and 1.8 GHz (Nelson 2003). The dielectric constant and loss factor of flaxseed increased with an increase in moisture content and bulk density and with a decrease in frequency (Sacilik et al 2006).…”

Section: Factors Affecting the Dielectric Propertiesmentioning

confidence: 99%

“…In order to understand interaction between the fruit and vegetables and electromagnetic energy, dielectric properties of fresh fruits and vegetables have been explored by several researchers (Garcia et al 2001;Kato 1997;Nelson et al 1994;Nelson 2003;Sosa-Moralesa et al 2009;Tran et al 1984). Microwave permittivities, or dielectric properties of fresh fruits and vegetables have been considered for potential use in non-destructive sensing of quality factors, such as maturity in peaches and chilling injury in sweet potatoes (Nelson 1980).…”

Section: Fruits and Vegetablesmentioning

confidence: 99%

“…Penetration depth decreased with increasing frequency and temperature. Radio frequency energy penetrates deeper in mangoes compared to microwaves and, thus, is more suited for potential postharvest disinfestation treatment of this fruit (Sosa-Moralesa et al 2009). Measured dielectric properties and sweetness of freshly harvested melons by soluble solids content with an open ended coaxial-line probe and an impedance analyser over the frequency range from 10 MHz to 1.8 GHz at 25°C and reported that correlations were low for both the dielectric constant and the loss factor at most frequencies (Nelson et al , 2007.…”

Section: Fruits and Vegetablesmentioning

confidence: 99%

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Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

et al. 2011

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Non-destructive systems are recent trends for quality evaluation of fruits and vegetables. Information on post-harvest variations in electrical properties is needed to develop new instruments for this purpose. Electrical properties are finding increasing application in agriculture and food processing industries. Knowledge of dielectric properties of foods as a function of moisture content and temperature is essential in the design and control of drying systems. As simple, rapid and non-destructive measuring techniques, dielectric spectroscopy provides information about the dielectric response of materials to electromagnetic field. Electrical properties of agricultural materials have been of interest for many years. The interest in dielectric properties of materials has historically been associated with the design of electrical equipment. This review paper covers theoretical aspects of different electrical properties, their measurement techniques, applications of dielectric properties in agriculture/food processing sector and potential applications of thermal imaging (TI) for quality and safety assessment in food processing. The values of dielectric properties of a number of products including food grains, fruits and vegetables, and meat and meat products are presented in table form. This comprehensive coverage will be useful for academic, scientific and industrial community in treating and applying the facts in developing/testing new processes and products based on electromagnetic energy application.Keywords Electrical properties . Non-destructive . Measuring techniques . Dielectric constant . Loss factor . Thermal imaging technique . Food quality evaluationThe material investigation and moisture measurement using electromagnetic waves in wide spectrum serve for quality control and improvement in many branches like industry, forest and wood-working industry, civil engineering, agriculture, commerce and also foods e.g. for quality evaluation of meat, fruits, coffee etc (Hlavacova 2003; Venkatesh and Raghavan 2004). Non-destructive evaluation of quality based on constituents of fruits and vegetables has been successfully used (Chen et al. 1999;Jha et al. 2001;Kawano 1998). Electrical characteristics of agricultural materials have been of interest for many years (Nelson 2006) and are utilized in many areas of human activities. Techniques for non-destructive determination of quality and related characteristics of agricultural products are helpful to producers, handlers and processors . Permittivity and moisture can be closely correlated when water content is high. Knowledge of dielectric properties in partially frozen material is critical in determining the rates and uniformity of heating in microwave thawing. Electrical properties are important in processing foods with pulsed electric fields, ohmic heating, induction heating, radio frequency, and microwave heating. These properties are also useful in the detection of processing conditions or the quality of foods (Barbosa-Canovas et al. 2006). Considering ...

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Section: Factors Affecting the Dielectric Propertiesmentioning

confidence: 99%

Section: Fruits and Vegetablesmentioning

confidence: 99%

Section: Fruits and Vegetablesmentioning

confidence: 99%

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Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

et al. 2011

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“…Calay et al (1995) observed that the dielectric constant of fruits increases with temperature, whereas the loss factor may either increase or decrease with increasing temperature, depending on the operating frequency; at higher frequencies the loss factor generally increases with increasing temperature (Nelson, 2003;Sosa-Morales et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Dielectric Spectroscopy of Grape Juice at Microwave Frequencies

Vijay¹,

Jain²,

Sharma³

2015

International Agrophysics

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A b s t r a c t. The complex permittivity of fresh juice of two cultivars of grapes, Sultania (green grapes) and Black Monukka (black grapes) was measured in terms of the dielectric constant and dielectric loss factor over the frequency range from 1 to 50 GHz and at temperatures ranging from 30 to 60 o C, by using the PNA network analyzer model E8364C and open ended coaxial probe 85070E. The Cole-Cole plots and dielectric constant vs. (angular frequency) dielectric loss factor and dielectric constant vs. dielectric loss factor/(angular frequency) regression lines at different temperatures were used in Debye approximation to predict relaxation frequency of molecules for the two cultivars of grapes in the low frequency and high frequency limits, respectively. It was observed that the acidic character of green grapes is responsible for the large amplitude vibrational peaks in dielectric loss factor -frequency curves, in the high frequency region at higher temperatures. On the other hand, excess of sugar in black grapes suppresses the activity of water molecules, thereby suppressing the vibrational peaks at higher frequencies. Different relaxation frequencies found for the two cultivars of grapes suggest that they have different molecular structure.K e y w o r d s: dielectric constant, dielectric loss factor, relaxation frequency, temperature, grapes INTRODUCTION

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“…It is represented as " r ¼ " 00 À j" 00 , where ε´and ε´´are commonly called dielectric constant and loss factor, respectively, and j is the complex constant j ¼ ffiffiffiffiffiffi ffi À1 p À Á . In the real part of the equation, the dielectric constant describes the ability of a material to store energy in response to an applied electric field; whereas in the imaginary part, the loss factor describes the ability of a material to dissipate energy in response to an applied electric field, which typically results in heat generation (Sumnu and Sahin 2005;Coronel et al 2008a;Sosa-Morales et al 2009;Wang and Wang 2009). The dielectric constant and the dielectric loss factor are dimensionless, since they are defined relative to the permittivity of free space (Datta et al 2005).…”

Section: Dielectric Properties Of Fluid Foodsmentioning

confidence: 99%

Recent Studies Related to Microwave Processing of Fluid Foods

Salazar-González

Martín-González

López‐Malo

et al. 2011

Food Bioprocess Technol

164

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Microwave heating is a convenient way to heat materials; it is considered to be a fast, clean, and easy to use technology. The use of microwaves for industrial food unit operations is the subject of research since several years ago. However, the application of microwaves depends, among other variables, on the dielectric properties of the material to be heated; otherwise, the efficiency of the process and the quality of the final product cannot be guaranteed. This paper reviews basic concepts related to microwaves and dielectric properties, and then it presents reported dielectric properties data for selected fluid foods and microwaveheating processes that have been recently studied. These processes are focused mainly on microbial inactivation, enzyme inactivation, chemical, physical, or sensory changes evaluation, or for reheating. The temperature uniformity is also discussed as a key issue for successful application of microwave heating, which is now applied by some companies.

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Dielectric heating as a potential post-harvest treatment of disinfesting mangoes, Part I: Relation between dielectric properties and ripening

Cited by 64 publications

References 22 publications

Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

Measurement techniques and application of electrical properties for nondestructive quality evaluation of foods—a review

Dielectric Spectroscopy of Grape Juice at Microwave Frequencies

Recent Studies Related to Microwave Processing of Fluid Foods

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