• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.561-567
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• 2000

This study was conducted to determine the effect of far infrared-vacuum drying on the quality changes of Pimpinella bracycarpa, such as drying efficiency (weight loss), color differences, browning degrees, rehydration and sensory evaluation. Wehn Pimpinella bracycarpa was dried for designated time at 5$0^{\circ}C$, 6$0^{\circ}C$ and 7$0^{\circ}C$, drying time of far infrared-vacuum drying was decreased more than 17% compared to that of infrared drying. The color changes increased as drying temperature increased and far infrared-vacuum drying made less color changes than infrared drying. Also, the total microbial counts and the number of yeast and mold were gradually reduced as drying temperature increased and drying time was longer, but there was no significant differences in microbial changes among drying methods. The rehydration rates of Pimpinella bracycarpa increased as drying temperature increased and was better at far infrared-vacuum drying than infrared drying. Also, according to the sensory evaluation after rehydration of Pimpinella bracycarpa, the hihger scores were obtained at lower temperature and far infrared-vacuum drying, especially the color was obtained much hihger score in the far infrared-vacuum drying than infrared drying. Thus, the results showed that drying efficiency and stability of rehydration and color changes was increased and the quality deterioration of Pimpinella bracycarpa could be minimized by using far infrared-vacuum drying.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.288-301
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• 2002

A vacuum freeze drying experiment of skim milk solution in a cylindrical container is conducted to investigate the multi-dimensional drying characteristics of the process during the primary drying stage. Temperature histories at several positions are measured under the same process condition that is carefully controlled. Then the measured temperature histories at different positions are combined to produce instantaneous temperature distribution fields inside the cylindrical container. Along with the temperature measurement, the mass reduction history of the skim milk solution is also measured. From the measured temperature distribution curved configurations of sublimation interfaces and 2-dimensional heat transfer is inferred. The freeze drying under the present experimental setup is simulated with a calculation program that is based on a finite volume method with a moving grid system. Good agreements between the numerical and experimental results are observed. The present experimental results and the numerical approaches can be useful information in developing the analysis tools for practical vacuum freeze drying processes.

• Korean Journal of Pharmacognosy
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• v.40 no.3
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• pp.178-183
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• 2009

In DPPH radical and nitric oxide scavenging ability, the extract of lowest temperature condition(40-15H ; 15 hours at $40^{\circ}C$ for drying) exhibited highest activity. The total phenolic and flavonoid contents of each extracts were found to be $120.4{\sim}193.3\;mg$/g and $86.91{\sim}94.55\;mg$/g respectively. It is shown that 40-15H was the highest content in each compound. In antimicrobial activity, a lower drying temperature conditions were found to be more strong activities in disc diffusion assay and each extracts showed MIC of identical level against every tested microbial strains. However 100-2H(2 hours at $100^{\circ}C$ for drying) was exhibited MIC of slightly low level against some strains. And every extract showed fine cell viabilities($101.7{\sim}122.9%$) against RAW 264.7 cell. In anti-proliferation activity against AGS, each extract showed a similar inhibition activity. However in anti-proliferation activity against HeLa, a lower drying temperature conditions showed more strong activities.

• Journal of Biosystems Engineering
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• v.15 no.3
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• pp.230-243
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• 1990

This study was conducted to investigate the possibility of application of an infrared drying to drying process for red pepper. The performance of seramic heaters and the variation of temperature and moisture content of red pepper were analyzed during an infrared drying of red peppers. Also, the quality of dried red pepper was analyzed. The following results were obtained from this study. 1. The surface temperature of infrared heaters and the rising time required for steady state were mainly affected by electrical power consumed. 2. The heat energy required for heating red pepper was proposed to be calculated by the equation in terms of enthalpy of air and net heat flux by infrared heater in a drying chamber. The statistical model for net heat flux was developed. 3. The performance of the infrared heater used for heating red pepper was much affected by the distance of radiation, and the difference of temperatures appeared between the radiated surface and the inside of red pepper. 4. Electrical capacity of the infrared heater had a significant effect on the heating of red pepper. However, the effect of shape of heater on heating was not significant. 5. The variation of temperature of red pepper largely appeared in the range of 30 to 60% (db) in moisture content. The temperature of red pepper was almost constant at low moisture content. 6. The temperature of red pepper and heating time had significant effects on the quality for radiant heating. 7. When the electrical capacity of infrared heater and the distance of radiation are carefully designed in a dryer with the insulated drying chamber, infrared drying might be very effective in red pepper drying.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1297-1301
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• 2003

The response surface methodology was peformed by central composite design based on drying temperature and time of Citrus, to monitor quality property change caused by drying and make dried products with a good overall palatability. In result, water activity, hardness and softness were affected by drying temperature; water activity decreased and hardness increased with increase of drying temperature. Softness was also high at low temperature and short time of drying. In the range of overall palatability having high score, hardness was shown in 2.01 ∼ 3.20${\times}$10$^{6}$ dyn/$\textrm{cm}^2$ and softness was 62.54 ∼ 146.37 cm/kg. Drying conditions satisfying this range were predicted as 66 ∼ 75$^{\circ}C$ of drying temperature and 8 ∼ 14 hr of drying time.

• Journal of Ginseng Research
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• v.27 no.3
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• pp.141-145
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• 2003

The multi-year production cycle for ginseng can be rapidly depreciated by inferior post-harvest activities. This research examines the character of high temperature drying regimes for North American ginseng root to assist management decision making. The objective is a very rapid drying regime, that will not result in physical or chemical damage to the root and that would not alter the actual dry root weight. Research is presented using drying temperatures of 55, 70 and 105 C. Temperatures above these rapidly cause substantive physical damage to the root samples and seriously compromise the dry root values determined. Temperatures below these behaved quite similar to actual dryer regimes (approximately 38 C). Laboratory results indicate that there are differences between the three temperature regimes tested. Careful usage of the 70 C regime, over a period of two to three days in a convection drying oven, has distinct merit.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.2
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• pp.12-17
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• 2003

The effects of wet pressing and drying conditions on the disintegration and physical properties of paper were investigated in order to get the basic information on the resistance of paper for aqueous solution during converting processes. Wet pressing of unbeaten bleached softwood kraft pulp increased WRV at the range of grammage investigated. The increase of WRV with grammage at low wet pressing pressure(50 psi) was obvious, while it was not significant at higher wet pressing pressure(110 psi). The changes of WRV by drying were affected by the grammage and wet pressing pressure. The poorer disintegration of sheet, the higher wet pressing pressure and drying temperature. Although the strength properties were increased with the grammage, wet pressing pressure and drying temperature, results showed different trend from those of beaten pulp.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.6-9
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• 1992

The browing, pyruvate content of sliced garlic during the drying in terms of drying temperature and sulfiting treatment were investigated. Sulfiting reduced the browning of garlic slices and prevented the reduction of pyruvate content against heat during the drying. Contents of pyruvate were decreased as the increase of drying temperature. Sulfiting treatment killed the microorganisms of sliced garlic products during the drying.

• Food Science and Preservation
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• v.1 no.2
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• pp.99-105
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• 1994

To convert the analog signal from the drying process into the digital signal, the interface circuit was designed and built. To measure the weight and temperature during drying process, strain gauge type load cell and temperature transducer composed of pt 100 $\Omega$ thermometers and wheatstone bridge circuits were built and used. The temperature control device was composed of photocoupler and triac. Microcomputer aided experimental convective drying system was built with above cricuits and devices. Drying characteristics of onions can be estimated using this system.

• Journal of the Korean Wood Science and Technology
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• v.10 no.3
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• pp.167-167
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• 1982

Italian poplar (Populus euramericana) rotary veneers were press-dried and air-dried to study drying curves, thickness shrinkage and width shrinkage of them under several drying conditions such as drying temperatures and veneer thicknesses. The results of the study are summarized as follows; 1. In press-drying, drying times from green condition to about final moisture content of 10 percent with veneer thickness of 0.6mm by platen temperatures required about 10 minutes at platen temperature of $100^{\circ}C$, 3 minutes at $110^{\circ}C$, 1 minute at $120^{\circ}C$ and $130^{\circ}C$, respectively. 2. In press, drying, drying times from green condition to about final moisture content of 10 percent by veneer thicknesses required 2 minutes at veneer thickness of 0.6mm, 4 minutes at 1.2mm,6 minutes at 1.8mm and 9 minutes at 3.6mm, respectively. 3. In air-drying, drying times from green condition to air-dried moisture content by veneer thicknesses required 15 hours at veneer thickness of 0.6mm, 18 hours at 1.2mm and 23 hours at 2.4mm, respectively. 4. Thickness shrinkage of press-drying was remarkably greater than that of air-drying, but width shrinkage of press-drying was rather smaller. 5. Difference of thickness shrinkage among platen temperatures was insignificant, and width shrinkage at platen temperature of $130^{\circ}C$ was the least.