• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.654-658
• /
• 2000

Flavor components focused on the methyl pyrazines(2,3-dimethyl pyrazine, 2,3,5-trimethyl pyrazine, tetramethyl pyrazine) of microwave-roasted cocoa beans were determined and compared with those of conventionally-roasted cocoa beans. Domestic microwave oven was modified to design the microwave roasting system. Temperature measurement technique using thermocouple probes was developed to determine the center temperature of cocoa beans during microwave roasting. Microwave roasting was carried out under two different conditions. Under the first condition, roasting time was fixed to 30 min, while roasting temperature was varied to $110^{\circ}C,\;120^{\circ}C,\;130^{\circ}C,\;140^{\circ}C,\;and\;150^{\circ}C$ Under the second condition, roasting temperature was fixed to $130^{\circ}C$, while roasting time was varied to 5 min, 10 min, 20 min, and 30 min. Conventional roasting was done at $120^{\circ}C$ for 15 min as a reference. Amount of methyl pyrazines and their ratios were influenced by microwave roasting temperature and roasting time. The most suitable methyl pyrazine ratio of cocoa beans was obtained at $140^{\circ}C$ for 30 min of microwave roasting.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.29 no.1
• /
• pp.168-173
• /
• 2000

The purpose of this study was to investigate the changes of microsomal mixed function oxidase (MFO) and xanthine oxidase activities (XOD) in the liver of rats exposed to microwave. Sprague-Dawley male rats weighing 200$\pm$10g body weight were randomly assigned to a normal and microwave exposed(MW) groups; microwave exposed groups were divided into two groups; microwave (MW) group and green tea(GT) gropu which were fed distilled water and green tea extracts during experimental periods, respectively. Rats were irradiated with microwave at the frequency of 2.45 GHz for 15min and rats wre sacrificed at the 4th day of the microwave irradiaton. The hemoglobin level of GT group was higher than that of the normal gropu and MW group, but the hematocrit value was not significantly different among all experimental gropus. The activity of serum GOT of MW group was significantly increased but that of GT group was similar to normal group. Activities of GPT were not significantly different among all experimental groups. Liver XOD activity was significantly increased in the microwave exposed groups but green tea normalized the XOD activity. The activity of hepatic microsomal cytochrome P450 was significantly increased in MW group compared to normal group and that of GT group was similar to that of the normal group. The activity of hepatic microsomal NADPH-cytochrome P450 reductase was also significantly increased in MW group compared to normal group, but that of GT group was similar to that fo the normal group. In conclusion, the activities of MFO and XOD were elevated by microwave irradiaton, but the activation of MFO system as well as the damage of the liver by microwave were reduced by green tea supplementation.

• Korean Journal of Agricultural Science
• /
• v.45 no.4
• /
• pp.847-857
• /
• 2018

Recently, customers' demand and attention to dried agricultural products or foods have increased due to their convenience and nutritional values. Conventional drying methods such as solar drying and hot air drying have been most widely used for producing a large amount of dried agricultural products; however, those methods require quite a long time and high energy consumption. To compensate for these issues associated with conventional methods, dielectric heating such as microwave and radio frequency heating has been used as a supplemental method in the drying procedure. This study investigated the microwave drying characteristics of squash slices with different thicknesses under different microwave power intensities and determined the best drying model that could precisely describe the experimental drying curves of the squash slices. The squash was cut into slices with two different thicknesses (5 and 10 mm), and then, they were dried under different microwave power intensity ranges between 90 and 900 W with an increase interval of 90 W. Six drying models were tested to evaluate the fit to the experimental drying data, and the effective moisture diffusivity ($D_{eff}$) values of the squash slices under microwave drying were determined. The results clearly show that as the microwave power was increased, the drying time of both squash slices was significantly decreased, and the slope of the drying rate increased. The effective moisture diffusivity was also significantly related with the microwave power intensities and thicknesses of the slices. In addition, the Page model was most suitable to delineate the drying curves of both squash slices under different microwave power intensities.

• Food Science of Animal Resources
• /
• v.28 no.4
• /
• pp.499-504
• /
• 2008

Even though pork have frequently induecd allergic reactions in Korea, few papers have been published on pork allergy. This study was carried out to investigate the changes in allergenicity of porcine serum albumin (PSA) by microwave, sonication, and high hydrostatic pressure (HHP). The binding ability of p-IgG to PSA treated with microwave (1,5, or 10 min) directly decreased with increasing treatment time. Particularly, the binding ability of PSA treated 10 min was about 30%. Immunoblotting assay with p-IgG showed that band of PSA treated microwave directly disappeared at 5 and 10 min. However, the binding ability of PSA was not changed by the microwave treatment without heat. Also the reduction of allergenicity by sonication or HHP treatment was not found. In conclusion. allergenicity of PSA treated with microwave directly decreased with increasing time, therefore these results may be used for development of hypoallergenic pork.

• 한국전산유체공학회:학술대회논문집
• /
• 2009.11a
• /
• pp.145-150
• /
• 2009

In this study, characteristics of microwave and convective drying are studied by using a multiphase porous media model. Temperature and moisture profiles for hot-air convective heating and microwave heating of 1-D porous media with varying time and space are numerically investigated. This result shows the microwave drying method is more effective than the convective drying method. Comparing to convective drying, microwave drying can increase temperature and evaporation rate significantly since microwave generates internal heat and increases internal pressure, which results in moisture movement toward the surface on which moisture is vaporized.

• Journal of the Korean Ceramic Society
• /
• v.34 no.9
• /
• pp.935-940
• /
• 1997

This study investigated the crystallization behavior in PbO-ZnO-B2O3-TiO2 system sealing glass, inorganic polymer heat-treated by conventional heat and microwave energy. After determining heat-treated temperature for crystallization and characteristic points by DTA analysis, samples were heat-treated in a classical electric furnace and a home-style microwave oven (LG Electronic Co., 2.45 GHz, 700 W). A microwave heat-treated sample had the growth of PbTiO3 crystal at 45$0^{\circ}C$, 2$0^{\circ}C$ lower than that of a conventionally heat-treated sample. Also, it had crystallinity about 20% higher than the conventionally heat-treated sample. At 49$0^{\circ}C$, the size of PbTiO3 crystal in the conventionally heat-treated sample was larger than that in the microwave heat-treated sample due to longer heat-treated time.

• Journal of Environmental Science International
• /
• v.17 no.5
• /
• pp.493-500
• /
• 2008

This paper describes the adsorption/desorpton efficiency of a modified activated carbon by irradiated microwave to treat toluene. By employing microwave energy, the regeneration time was considerably shortened compared with conventional thermal heating regeneration. New adsorbent called ACB (Activated Carbon-Bentonite) was prepared from powder activated carbon with mixing bentonite as a binder. Specific surface area, average pore size and total pore volume of ACB were calculated from the nitrogen adsorption/desorption isotherm. The surface of ACB was characterized with scanning electron microscope(SEM). The results showed that the specific surface area, total pore volume, average pore size of ABC was not influenced by regenerating cycle with microwave irradiation. Toluene was adsorbed onto ACB which desorbed by MW irradiation. Absorption capacity of ACB was 0.117 $g_{toluene}/g_{ACB}$. Desorption efficiency of toluene increased as higher microwave output was applied.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.471-474
• /
• 2008

The pyrolytic behavior of waste tire under microwave heating was investigated. Experiments were conducted using a lab- and bench-scale system to delineate the effects of microwave output power on the response. As the results of experiments, it was found that as the microwave output power was increased between 0.84 and 3.04 kW/kg, the oil yield and required time rapidly increased and decreased, respectively. With further increase of the microwave output power, the oil yield and required time did not change significantly.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.12 s.177
• /
• pp.141-148
• /
• 2005

When one opens the door of a microwave oven during operation, microwave might leak through the clearance of the door. Present research has been motivated by the need to reduce the possible clearance by enhancing torsional stiffness of the door of the microwave oven. Static deformation of the door frame of the oven is analyzed under a door-opening force. On the basis of the topological optimization, the right flange of the door frame is shown to need reinforcing. Several types of reinforcing brackets weldable to the right flange is proposed, and their effects to the stiffness of the door frame are compared and evaluated.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.1012-1014
• /
• 2003

Since it's establishment Malaysian Center for Remote Sensing (MACRES) has focused on the measurements from airborne and space borne remote sensors. In the year 1999 MACRES in collaboration with Multimedia University Malaysia (MMU) began developing it's own remote sensing sensors to meet Malaysian Remote Sensing needs. MACRES adopted a very systematic approached to the development of these microwave sensors. Starting from non-imaging ground base microwave remote sensing sensors MACRES is now well into developing it's first Airborne Synthetic Aperture Radar. With the capability of developing it's own sensors MACRES will profit more on the microwave remote sensing application research. This paper will demonstrate MACRES capability in developing Microwave Remote Sensing Sensors to meet Malaysian remote sensing society needs.