Using Capacitive (Radio Frequency) Dielectric Heating in Food Processing and Preservation – A Review

Zhao, Yanyun; Flugstad, Ben; Kolbe, Edward; Park, Jae W.; Wells, John Henry

doi:10.1111/j.1745-4530.2000.tb00502.x

Cited by 146 publications

(71 citation statements)

References 25 publications

(17 reference statements)

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“…Microwave and radio-frequency heating are both dielectric heating, but microwave heating occurs at higher frequency (915 and 2,450 MHz) and the wavelength is small, whereas the radio-frequency heating occurs at lower frequency (13.56, 27.12, and 40.68 MHz) and the wavelength is large compared to the dimensions of the sample being heated (Zhao et al 2000;Tewari 2007). Microwave heating is employed in industries for certain unit operations.…”

Section: Industrial Applications Of Microwave Energymentioning

confidence: 96%

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Vadivambal

Jayas

2008

Food Bioprocess Technol

415

186

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Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the nonuniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.

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Section: Industrial Applications Of Microwave Energymentioning

confidence: 96%

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Vadivambal

Jayas

2008

Food Bioprocess Technol

415

186

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“…Dielectric heating is an alternative method for conventional heating [5,6]. Compared with conduction/convection heating, which is based on superficial heat transfer, dielectric heating uses the ability of some compounds to transform electromagnetic energy into heat; thus, heating is volumetric and rapid [7].…”

Section: Introductionmentioning

confidence: 99%

Alkali (NaOH) Pretreatment of Switchgrass by Radio Frequency-based Dielectric Heating

Wang

Wen

2007

Appl Biochem Biotechnol

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Radio-frequency (RF)-based dielectric heating was used in the alkali (NaOH) pretreatment of switchgrass to enhance its enzymatic digestibility. Due to the unique features of RF heating (i.e., volumetric heat transfer, deep heat penetration of the samples, etc.), switchgrass could be treated on a large scale, high solid content, and uniform temperature profile. At 20% solid content, RF-assisted alkali pretreatment (at 0.1 g NaOH/g biomass loading and 90 degrees C) resulted in a higher xylose yield than the conventional heating pretreatment. The enzymatic hydrolysis of RF-treated solids led to a higher glucose yield than the corresponding value obtained from conventional heating treatment. When the solid content exceeded 25%, conventional heating could not handle this high-solid sample due to the loss of fluidity, poor mixing, and heating transfer of the samples. As a result, there was a significantly lower sugar yield, but the sugar yield of the RF-based pretreatment process was still maintained at high levels. Furthermore, the optimal particle size and alkali loading in the RF pretreatment was determined as 0.25-0.50 mm and 0.25 g NaOH/g biomass, respectively. At alkali loading of 0.20-0.25 g NaOH/g biomass, heating temperature of 90(o)C, and solid content of 20%, the glucose, xylose, and total sugar yield from the combined RF pretreatment and the enzymatic hydrolysis were 25.3, 21.2, and 46.5 g/g biomass, respectively.

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“…Since the primary cause of the change in PNIPAm is heat, the ability of a PNIPAm-based material to couple to radio-frequency stimuli is dependent on the Radio-frequency actuated polymer-based phononic meta-materials E Walker et al dielectric parameters, specific heat and electric field strength inside the material. 34,35 The relatively weak EM and more specifically the radiofrequency response necessitates increased susceptibility to RF to successfully obtain amplified responsiveness. [36][37][38] An applied EM field results in a rearrangement of the charges as they tend to align with the external field.…”

Section: Rf Actuated Acoustic Materialsmentioning

confidence: 99%

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

Walker

Wang²,

Neogi

2017

NPG Asia Mater

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Radio-frequency (RF) control of an ultrasonic phononic crystal was achieved by encapsulating it in a composite of high k-10% KF-doped BaTiO 3 dielectric nanoparticles with poly(N-isopropylacrylamide) (PNIPAm)-based hydrogel. The combination of the nanoparticles and hydrogel produced a composite with elastic properties susceptible to RF actuation. The novel acoustic meta-material enables the regulation of sound waves by electromagnetic waves, which is not possible in a conventional medium as elasto-mechanical waves, and electromagnetic waves do not directly couple. Compared with light waves, radio waves can penetrate deeper into bulk structures and enable the control of propagation of ultrasonic waves through a macroscale phononic crystal. An RF antenna emitting at 318.6 and 422.5 kHz was used to modulate the device in water and ambient air, respectively. An increased transparency of the ultrasonic wave in the material was observed due to an increase in the bandwidth of the modulated device exceeding 8 kHz with a 30-fold increase in the signal modulation at select frequencies. The radio waves induced changes in the transmission and demonstrated the control of ultrasound with applied RF. The synthetic acoustic properties in the resultant meta-material device were actively manipulated through the interaction of electromagnetic waves with the material.

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Using Capacitive (Radio Frequency) Dielectric Heating in Food Processing and Preservation – A Review

Cited by 146 publications

References 25 publications

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Alkali (NaOH) Pretreatment of Switchgrass by Radio Frequency-based Dielectric Heating

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

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