Temperature Distribution of Microwave Heating―Spheres and Cylinders

Ohlsson, Thomas; Risman, Per Olov

doi:10.1080/16070658.1978.11689110

Cited by 117 publications

(60 citation statements)

References 7 publications

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“…2a). In case of microwave blanching of food stuff, the heat distribution within the matrix is a more complex phenomenon which can be influenced from the frequency of the electromagnetic energy, the cavity of treatment dimensions, the position of the sample in the cavity, the shape, size, composition and properties of the product (Ohlsson et al, 1978). In our case as illustrated in the cross-section of the cylindrical sample at the infrared thermal image in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Both water and microwave blanching are dynamic processes and time of treatment is an influential parameter that needs to be optimized not only in terms of enzymatic inactivation but also regarding the mass transfer and temperature distribution. Further to expected temperature gradients other important aspects should be taken into account during microwave thermal treatments, such as the penetration depth as well as the effect of the shape, size and dielectric properties of the samples on the electromagnetic field distribution (Ohlsson, Risman, & Rismanj, 1978). All these factors make a microwave blanching process difficult to be tuned and precisely controlled.…”

Section: Introductionmentioning

confidence: 99%

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Effect of microwave assisted blanching on the ascorbic acid oxidase inactivation and vitamin C degradation in frozen mangoes

Xanthakis

Gogou

Taoukis

et al. 2018

Innovative Food Science & Emerging Technologies

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of microwave assisted blanching on the ascorbic acid oxidase inactivation and vitamin C degradation in frozen mangoes

Xanthakis

Gogou

Taoukis

et al. 2018

Innovative Food Science & Emerging Technologies

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“…Strong focusing effects are exhibited by geometrical shape of mushroom hat. Ohlsson and Risman [127] have shown that core heating releases steam which induces an energy impulse of sufficient power to cause mechanical stress within the heated material. This deleterious phenomenon is optimum for an egg of diameter close to 40 mm.…”

Section: Dimensional Resonancesmentioning

confidence: 99%

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Stuerga¹

2006

Microwaves in Organic Synthesis

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The main focus of the revised edition of this first chapter is essentially the same as the original -to explain in a chemically intelligible fashion the physical origin of microwave-matter interactions and, especially, the theory of dielectric relaxation of polar molecules. This revised version contains approximately 60% new material to scan a large range of reaction media able to be heated by microwave heating. The accounts presented are intended to be illustrative rather than exhaustive. They are planned to serve as introductions to the different aspects of interest in comprehensive microwave heating. In this sense the treatment is selective and to some extent arbitrary. Hence the bibliography contains historical papers and valuable reviews to which the reader anxious to pursue particular aspects should certainly turn.It is the author's conviction, confirmed over many years of teaching experience, that it is much safer -at least for those who rate not trained physicists -to deal intelligently with an oversimplified model than to use sophisticated methods which require experience before becoming productive. Because of comments about the first edition, however, the author has included more technical material to enable better understanding of the concepts and ideas. These paragraphs could be omitted, depending on the level of comprehension of the reader. They are preceded by two different symbols -k for TOOLS and j for CONCEPTS.After consideration of the history and position of microwaves in the electromagnetic spectrum, notions of polarization and dielectric loss will be examined. The orienting effects of electric fields and the physical origin of dielectric loss will be analyzed, as also will transfers between rotational states and vibrational states within condensed phases.Dielectric relaxation and dielectric losses of pure liquids, ionic solutions, solids, polymers and colloids will be discussed. Effect of electrolytes, relaxation of defects within crystals lattices, adsorbed phases, interfacial relaxation, space charge polarization, and the Maxwell-Wagner effect will be analyzed. Next, a brief overview of 1 thermal conversion properties, thermodynamic aspects, and athermal effects will be given.

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“…In a slab with sharp corners and edges protruding into the microwave fields, energy concentrations will occur causing selective heating, especially at the corners. A sharp edge or corner will act as an antenna and attract more energy than the surrounding areas (Ohlsson and Bengtsson, 2001;Ohlsson and Risman, 1978). These effects are well documented in many literatures (Chamchong and Datta, 1999;Ni et al, 1999;Ohlsson et al, 1974;Zeng and Faghri, 1994).…”

Section: Introductionmentioning

confidence: 81%

Cooking Pattern and Quality Properties of Ground Pork Patties as Affected by Microwave Power Levels

Jeong¹,

Lee²,

Choi³

et al. 2009

Korean Journal for Food Science of Animal Resources

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This study was carried out to evaluate the effects of microwave power level on cooking properties of ground pork patties (fat level: 20%). Each patty was cooked from a thawed state to 76.7 o C (center temperature) in a microwave oven with power levels of 40% (360 W), 60% (540 W), 80% (720 W), and 100% (full power, 900 W), respectively. Cooking rate increased with power level, and the non-uniformity also increased with time during cooking. Overheating at the edge of the patties was observed for all power levels, and maximum temperature differences in between the edge position and center position were found in patties cooked at the 900 W power level. Compositional properties, total cooking loss, and drip loss were not affected by power level, although moisture content was lower at the edge than at the center position. As the power level increased, the reduction in patty diameter of cooked patties increased while the reduction in patty thickness decreased. Pork patties cooked at lower power levels (360 W and 540 W) had higher shear force values than those cooked at higher power levels (720 W and 900 W). Few changes were observed in instrumental color values.

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Temperature Distribution of Microwave Heating―Spheres and Cylinders

Cited by 117 publications

References 7 publications

Effect of microwave assisted blanching on the ascorbic acid oxidase inactivation and vitamin C degradation in frozen mangoes

Effect of microwave assisted blanching on the ascorbic acid oxidase inactivation and vitamin C degradation in frozen mangoes

Microwave‐Material Interactions and Dielectric Properties, Key Ingredients for Mastery of Chemical Microwave Processes

Cooking Pattern and Quality Properties of Ground Pork Patties as Affected by Microwave Power Levels

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