• Food Engineering Progress
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• v.13 no.3
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• pp.216-220
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• 2009

The several functional properties of freeze-dried powder of Aloe vera gel was examined as influenced by pre-concentration degrees of the gel solution. As a pre-treatment prior to freeze drying, the gel solution was vacuum-concentrated by three levels (unit: g-water/g-solids) - high (H), 76; medium (M), 119; low (L), 159. In FT-IR spectra, the sample H showed the highest absorbance in the range of 1600-1550 $cm^{-1}$ and 1450-1400 $cm^{-1}$, which corresponded to level of the acetyl group in glucomannan. The sample H of freeze-dried powder was the highest in polysaccharide content, jack bean urease inhibition rate, and FAC (fat adsorption capacity). It could be inferred that the sample H had an effect on Helicobacter pylori inhibition and fat adsorption suppression according to urease inhibition rate and FAC, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.2
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• pp.250-254
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• 2007

In an attempt to find ways of improving the quality of dried Shiitake mushroom, this study compared a conveyer-type far-infrared drying method with a traditional heated air drying method. The conveyer-type far-infrared dryer was performed at air velocity of 0.6 and 0.8 m/s under drying air temperature of 60, 70 and $80^{\circ}C$, respectively. Drying characteristics, antioxidant activities and the antioxidant compounds of Shiitake mushroom dried by far-infrared dryer were investigated. Generally, drying rate with the conveyer-type far-infrared drying method was faster than that with the traditional heated air drying method. In the conveyer type far infrared drying method, drying rates were increased with increasing temperature and air velocity. The loss of antioxidant activities during the conveyer-type far-infrared drying method at 60-0.6, 60-0.8, and $70^{\circ}C-0.6m/s$ was less than the traditional drying method. However, the loss of antioxidant activities at 70-0.8, 80-0.6, and $80^{\circ}C-0.8m/s$ was higher than that of the traditional drying method. Therefore, the conveyer type far infrared drying conditions with below $70^{\circ}C$ and 0.6 m/s air velocity may produce dried Shiitake mushroom with relatively higher antioxidant activities and antioxidant compounds.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.427-432
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• 1999

Changes in saponin composition and microstructure of ginseng by microwave vacuum drying were determined. Korean fresh ginsengs were subjected to four different processing : 3 min microwave vacuum drying and 2 min holding-24 hrs drying (MWVD1), 5 min microwave vacuum drying and 2.5 min holding-24 hrs drying (MWVD2), 3 min microwave vacuum drying and 2 min holding-12 hrs drying after hot air drying for 12 hrs drying at $45^{\circ}C$ (HMWVD1), 5 min microwave vacuum drying and 2.5 min holding-12 hrs drying after hot air drying for 12 hrs at $45^{\circ}C$ (HMWVD2). The water content was decreased until 16.82% without shrinkage and water activity was 0.54 after microwave vacuum drying. The lipid content was decreased after microwave vacuum drying (MVD). Glucose was increased after MVD while sucrose decreased. Ginsenoside-Rb1 and ginsenoside-Rc were decreased after MVD. Ginsenoside-Rg1 for MWVD2 and HMWVD2 was higher than that of MWVD1 AND HMWVD1. MWVD1 AND HMWVD1 dried ginsengs showed a more compact structure than the HMWVD2 and HMWVD2 ginsengs.

• Korean Journal of Food Science and Technology
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• v.25 no.4
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• pp.313-320
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• 1993

A sublimation model of the freeze drying process, which accounted for the removal of free water, was presented and used to study the operation conditions of freeze driers for carrot juice. It was found that the shortest drying time was obtained when the condenser temperature and chamber pressure were kept at heir lowest values and the plate temperature was controlled independently so that the scorch and melting constraints were both held throughout the drying period. The effect of sample thickness on the drying time was significant. Optimal policies were investigated experimentally in laboratory freeze dryer.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.479-484
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• 1986

Two different types of solar collector for farm dryer- the flatplate type and the modified tubular type-were constructed and analyzed on their performances. The transparent plastic film, black painted galvanized iron sheet and black vinyl film were used for the cover and absorber of the flat-plate types. The simplified tubular type was constructed with transparent films for the cover and black vinyl films for the absorber Two elliptical iron rings were used to form a tubular shape through which air could pass. No remarkable differences were found in thermal efficiences between the absorbers made with galvanized iron sheet and black vinyl film. The average thermal efficiencies of the solar collectors were 42.8%(max.48.2%, min.38.2%) for flat plate type and 22.971 (max. 25.4%, min. 14.8%)) for tubular one. The empirical equations were proved to be applicable to the prediction of temperature elevation. The tubular solar heat collector was successfully applied to red peppers drying as a practical farm dryer. The drying rate was almost doubled compared to a conventional sun drying.

• Food Science and Preservation
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• v.12 no.5
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• pp.436-441
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• 2005

This study was observed the effects of drying methods on the extraction characteristics of Rubi fructus (fruits of Rubus coreanus). Extraction yields of soluble solids and total sugar were high in the Rubi fructus dried by freeze drying, followed by infrared drying and sun drying. Extraction yield of phenolic compounds and DPPH radical-scavenging activity of extracts were in the following order; the Rubi fructus dried by freeze drying, the Rubi fructus dried by infrared drying, the Rubi fructus dried by sun drying. L value was the highest in the Rubi fructus dried by freeze drying, and a and b value were lowest in the fruit dried by freeze drying. These results suggest that freeze drying has an beneficial effect to enhance the quality of Rubi fructus. Water and ethanol extractions was more effective in the extraction of soluble solids and the antioxidative components.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.122-127
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• 1999

Quality changes of Korean ginseng on microwave drying were determined in terms of water activity, crude protein, crude lipid, crude ash, dielectric properties, content of sugar, ginsenoside composion, microstructure. Korean fresh ginseng were subjected to four different processing : 3 min microwave drying and 2 min holding-24 hrs drying (MWI), 5 min microwave drying and 2.5 min holding-24 hrs drying (MW2), 3 min microwave drying and 2 min holding-12 hrs after hot air drying for 12 hrs drying at $45^{\circ}C$ (MWH1), 5 min microwave drying and 2.5 min holding-12 hrs drying after hot air drying for 12 hrs at $45^{\circ}C$ (MWH2), Water content was decreased 14.33% without shrinkage and water activity was 0.57 after microwave drying. Permittivity was increased as water content increased. As temperature increased, permittivity was increased until $40^{\circ}C$ and fast decreased over $40^{\circ}C$. Content of ginsenoside for MW1 and MW2 was higher than that of MWH1 and MWH2. Data of free sugar showed that there was no significant difference in each treatment. The MW2 dried ginseng showed a more compact structure than the MWH2 ginseng.

• Korean Journal of Food Science and Technology
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• v.11 no.4
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• pp.264-272
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• 1979

The flat-plate and tubular soar collectors were designed and constructed for drying the rough rice, and the performance of the collectors and drying effect were investigated when rough rice was packed in grain bin connected to collectors. Average-monthly radiation on a horizontal surface based on bright sunshine in Daejeon area during 1978 was the highest as $16,814\;KJ/m^2{\cdot}day$ in May and the lowest as $4,254\;KJ/m^2{\cdot}day$ in December, and significane was not recognized between the calculated and recorded values. The thermal effciency of collectors were increased as radiation increased during drying period and the average thermal effciency of flat-plate and tubular collectors in 11 to 12 o'clock a.m were 28.12 and 16.75%, respectively. The average inlet temperature of grain bin at 12 o'clock was shown as 20.02 at control 40.5 at grain bin connected to tubular collector and $55.1^{\circ}C$ at grain bin connected to flat-plate collector. In 25 cm rough rice depth in grain bin, tim taken for drying from initial moisture content at 27.4 to decrease upto 17.0% (14.5 % on wet basis) were 32 in control, 18 in grain bin connected to tubular collector and 11 hrs to flat-plate collector, and grain depth influenced drying rate remarkably. In the view point of drying characteristics, drying pattern showed initially falling-rate to constant-rate period finally.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.330-338
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• 2002

This study was performed to develop natural spices and functional foods using Cheongung (Cnidium officinale) which is one of the Korean medicinal plants. The volatile flavor patterns of Cnidium officinale were detected by electronic nose with 6 metal oxide sensors, and the principal component analysis was carried out. The volatile flavor components of Cnidium officinale were isolated by simultaneous steam-distillation extraction with pentane and diethylether (1 : 1), and essential oils were analyzed by capillary GC and GC/MS. The free radical scavenging activity of ethanol and methanol extracts from Cnidium officinale was measured by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and compared with ${\alpha}-tocopherol$ as reference. The principal component analysis showed the difference of principal components between fresh and drying samples. Eighty-five volatile flavor components (643.64 ppm) from fresh Cnidium officinale were identified and the major components were butyl phthalide, sabinene, neocnidilide. Sixty-four volatile flavor components (218.15 ppm) from hot air dried one were identified and the major components were butyl phthalide, sabinene, 3-N-butyl phthalide. And 73 volatile flavor components (784.15 ppm) from freeze dried one were identified and the major components were butyl phthalide, sabinene, ${\beta}-selinene$. The free radical scavenging activity of methanol cold extract (500 ppm) of freeze dried Cnidium officinale was higher than other samples. And methanol and ethanol cold extracts (above 250 ppm) of freeze dried sample were higher than ${\alpha}-tocopherol$ $25\;{\mu}M$ (22.34%).

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.1
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• pp.64-69
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• 1992

To examine the effects of blanching treatments on the drying of hot red pepper, the pilot scale hot-air dryer equipped with the weight sensor using strain gauge type load cell and strain amplifier was designed and manufactured. The drying characteristic curves of cut hot red pepper showed a settling down period followed by a constant rate period and falling rate period, but blanched hot red pepper showed only falling rate period. According as the blanching time and temperature rises, the drying rates and the capsanthin contents of hot red pepper fairly increased. Considering the drying rates and the color values of dried hot red pepper, we suggest the desirable blanching condition of hot red pepper should be water blanching at $80^{\circ}C$ for 3 mins.