• Journal of Food Hygiene and Safety
• /
• v.18 no.4
• /
• pp.243-250
• /
• 2003

S-methylmethionine, vitamin U levels were affected by cultivars, parts fo Korean Chinese cabbages, and drying methods. Among drying conditions, freeze drying method appeared the best condition to maintain bitamin U content compared to oven and air drying methods. In the case of KOrean Chinese cabbages, outward leaves have high levels of chlorphyll and fiber. From this study, the outward parts contained high levels of vitamin U in two cultivars. Leaf parts were 1.1-21.2 times higher in vitamin U levels than midribs in both cultivars. This difference was shown most distinctively in freeze dried outward parts of Winter Pride cultivar. Like vitmnin U, fee amino acids also showed much higher levels in leaves. Levels of amino acids showed irregulatoy changing patterns at different parts and cultivar of Korean Chinese cabbages with various drying methods, Alanine and threonie appeared relatively aboundant amino acids in most parts of samples. Since no distinctive trends were observed in this rsult, it seems no relationship exists between amon oacids and bitamin U levels. Levels of methionine in differnent parts and cultivars of Korean Chinese cabbages dried with various methods did no show clear relationship with tlevel of vitamin U. Moreover, emthionine was not detected in freeze dired outward leaf parts which were the hithest parts of vitamin U levels in Winter Pride and 55 days cultivar. There were simila levels of methionine between overn and freeze drying. Samples prepared by air drying showed significatly lower levels than those by oven and freeze dryting. Methionine as aprecursor of vitamin U, may play a role in an increase of vitamin U during drying of KOrean Chinese cabbages.

• The Korean Journal of Food And Nutrition
• /
• v.22 no.2
• /
• pp.192-198
• /
• 2009

Cheongkukjang is a traditional fermented soybean food in Korea that is used in the manufacture of functional foods. This study was conducted to assess vitamin contents and sensory qualities of powdered Cheongkukjang dried by oven drying, far-infrared drying and freeze drying. Vitamins $B_1$, $B_2$, $B_6$, E, niacin and pantothenic acid were detected using all drying methods. However, vitamin D was not detected in the oven drying samples, and was most prevalent($82.47{\mu}g$/100 g) in the far-infrared drying samples. The sensory characteristics included color, off flavor, salty taste, bitter taste, sweet taste, roasted taste and after-taste. Oven drying and freeze drying samples exhibited highest and lowest color scores(5.62 and 2.0, respectively). Oven drying samples also exhibited the highest roasted taste score(4.76), although not significantly different from far-infrared drying samples(4.0, p<0.05), while the score of freeze drying samples(2.38) was significantly different from the other methods(p<0.05). It is concluded that freeze drying is most suitable.

• 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.

• Journal of the Korean Society of Food Culture
• /
• v.35 no.1
• /
• pp.28-54
• /
• 2020

This study aims to investigate the food preservation methods adopted by the Joseon Dynasty, which existed before the 17^th century. A total of 232 food preservation methods were discovered in 25 books, and could be classified by their targeted food types: vegetables (84), sea foods (60), meats (41), fruits (37), and others (10). Depending on the preservation method applied, they are classified as food drying, soaking, mud cellar preservation, and other preservation. Food drying is further classified into 8 sub-types: drying, sun-drying, shadow-drying, wind-drying, dry heat, combined drying, smoking, and others. Soaking could be sub-divided into using salt, ash, dry sand, bran, fermented paste, wet distillers grains, oil, and others. Mud cellar preservation is sub-classified into installing shelf inside the mud cellar, making the mud cellar for food preservation, and making hole or underground tunnel for food preservation. Other food preservation methods include minimizing moisture loss by applying beeswax on a section of the vegetable stem, and cutting the vegetables or fruits with their branches and leaves for food preservation.

• Journal of the Korean Wood Science and Technology
• /
• v.22 no.4
• /
• pp.37-42
• /
• 1994

The adsorption of water vapor and equilibrium moisture content(EMC) of the specimens for four softwood species dried by conventional- and high temperature method and equilibrated to 15% of the target EMC condition at 25$^{\circ}C$ were determined by oven drying method and with moisture meters. The amount of adsorption for high temperature dried red pine was significantly higher than that of conventional kiln dried wood, while those of eastern white pine, eastern hemlock and Norway spruce were not significantly different between drying methods. EMCs of these four species determined by oven drying method and with capacitive admittance moisture meter were not significantly different between drying methods. EMC of high temperature dried red pine determined with resistance moisture meter was significantly higher than that of conventional kiln dried wood. But EMCs of other species did not show significant difference between drying methods. EMCs of conventional and high-temperature dried wood determined with electronic moisture meters, especially in the case of the capacitive-admittance moisture meter measurement, were lower than that determined by oven drying method.

• Journal of the Korean Wood Science and Technology
• /
• v.36 no.5
• /
• pp.49-55
• /
• 2008

This study was carried to investigate the effects of steaming and four different drying methods on the longitudinal liquid permeability of Korean pine (Pinus koraiensis Sieb.et Zucc.) board. Four drying methods were air drying, conventional kiln drying, microwave-vacuum drying and high temperature drying. Darcy equation was used for calculating the specific permeability of the small sapwood specimens taken from the treated boards while capillary rising method was used for the heartwood specimens. The sapwood specimens were extracted with water and benzene-alcohol solution to examine the mechanism of liquid flow in treated wood. No significant correlation was found between specific permeability and the number of resin canals of the sapwood specimens. Extraction decreased the differences of specific permeabilities of the sapwood specimens between the five treatment methods. The effects of extraction on the longitudinal permeability are different between five treatments. The fluid path in heartwood was observed by dynamic observation method.

• Korean Journal of Medicinal Crop Science
• /
• v.14 no.1
• /
• pp.8-13
• /
• 2006

This study was carried out to investigate drying methods for keeping freshness and active components of aerial part of Saururus chinensis. Chopped samples were prepared using hot air drying, hot air drying + roasting, presteamed + hot air drying, freeze drying, and sun drying. Drying time was shorter $88{\sim}93%$ in hot air drying and freeze drying than in sun drying. Percentage of dry matter was higher in the order of freeze drying > sun drying > hot air drying, and moisture content in the order of sun drying > hot air drying > freeze drying. The contents of total phenolics and quercetin related substances were greater in the order of freeze drying > hot air drying > sun drying, while were decreased due to treatments before or after hot air drying. Electron donating ability (EDA) was highest in freeze drying, and showed a little difference between hot air drying and sun drying, but was increased because of treatments before or after hot air drying. In color values, the a value was lower in the order of freeze drying < hot air drying < sun drying. The contents of active components of plant parts of hot air dried were higher in the order of flower >leaf > chopped sample > stem. EDA showed similar tendency with those. The a value was lower in the order of leaf < chopped sample < flower < stem. As a result, freeze drying of chopped samples or hot air drying of leaf and flower were effective to maintain qualities of aerial part of Saururus chinensis.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.33 no.4
• /
• pp.234-239
• /
• 2013

This study investigated the effects of drying methods and drying time on the changes in anthocyanin content in colored barley. Colored barley cultivar Boanchalbori was harvested at a time when the anthocyanin content was the most and dried in afield. The harvested barley was then treated by two methods, sun drying and shade drying, for 4, 8, 24, and 32 h. The moisture content of the sun-dried barley decreased slightly faster than shade-dried samples, but the difference was not statistically significant. Chemical analysis indicated that the samples dried under shaded conditions had slightly higher crude fiber and lower nitrogen free extract, but the difference was not statistically significant. There was no difference in the total digestible nutrients between the two methods. In the case of sun-dried barley, the anthocyanin content decreased compared to the control and shade-dried samples after drying for 4 h (p < 0.05), was maintained at a constant level at 24 h, and then decreased at 32 h. In case of shade-dried barley, the anthocyanin content decreased gradually with the drying time, and a significant decrease was found at 24 h of drying (p<0.05) as compared to the control. The shade-dried method was more successful in reducing anthocyanin loss than the sun-dried method (p<0.05). There was a slight decrease in 1,1-Diphenyl-2-Picrylhydrazyl radical scavenging with drying time in the shade-dried method, and a significant decrease after 4 h with the sun-dried method. These results showed that covering with a two-layer awning was advantageous to dry colored barley in the field conditions.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.47 no.6
• /
• pp.459-464
• /
• 2002

This experiment was conducted to know the changes of bioactive component content in four-year-old peony (Paeonia lactiflora Pall.) root with various drying methods such as room temperature drying, $50^{\circ}C$ heat-air drying, room temperature drying after $80^{\circ}C$ boiling water treatment and freeze drying, and to establish the optimum drying method for high quality production of Paeoniae Radix. For this purpose, the contents of paeoniflorin, albiflorin and five phenolic compounds (gallic acid, benzoic acid, (+)-catechin, (-)-epicatechin and (+)-taxifolin 3-O-$\beta$-D-glucopyranoside) in peony root with different drying methods were analyzed by RP-HPLC. The contents of paeoniflorin, albiflorin and (+)-taxifolin 3-O-$\beta$-D-glucopyranoside at room temperature drying were higher than in the other drying methods and that of gallic acid at 8$0^{\circ}C$ boiling water treatment was the highest among that of all drying methods. In the case of freeze drying, the contents of (+)-catechin, benzoic acid and (-)-epicatechin were the highest among those of all drying methods. As increase of drying and treatment temperature, the contents of paeoniflorin, albiflorin, (+)-taxifolin 3-O-$\beta$-D-glucopyrano-side, (+)-catechin and benzoic acid were decreased.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.41 no.3
• /
• pp.362-369
• /
• 1996

Seven different drying methods were tested in peony roots of Euisung cultivar, harvested in February, in three year's old plant. The roots were selected in length and diameter and half of the samples were removed cork-layers to compare the effects of cork-layer in processing of drying. The 3$0^{\circ}C$ heat drying without cork-layer reduced in days to drying by five days compared to those of the with cork-layers at the same temperature. The 5$0^{\circ}C$ heat drying after cork-layers removed was the most effective in days to drying. In quality of skin color of the 5$0^{\circ}C$ heating was worse to compare with the lower drying temperature. In the drying at room temperature and the heat drying at lower temperature, the paeoniflorin content in drying after cork-layers removed were higher than that of the drying with cork-layers. However, in the boiling water treatment, the paeoniflorin contents in drying after cork-layers removed were lower than those of with cork-layers. In heat drying, paeoniflorin content showed a decreasing tendency to increase of drying temperature. Total sugars in the peony roots showed a decreasing tendency according to the drying temperature increasing, but starch concentration showed a increasing tendency at the same condition. Concentrations of crude protein, crude fiber and crude ash were showed no differences in various drying methods and the materials with or without cork-layers. Relationships between the paeoniflorin and total sugars, and the paeoniflorin and starch were different significantly by the materials of cork-layers removed or not. The 30~4$0^{\circ}C$ heat drying without cork-layers was the most advisable condition for drying in paeoniflorin concentration, days to drying and skin color after drying.