• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.635-641
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• 2006

In an attempt to find ways of improving the quality and sanitary state of dried squid, this study compared artificial drying methods i.e. hot air drying and cold air drying with natural drying method. The drying rates of squid were in the order of hot air, cold air and natural drying. However, cold-air drying was slower than natural drying at $7^{\circ}C$. The drying rates increased with increasing drying temperature. When drying temperature was close to the dew point on a dehumidifier surface, which was the case with cold air drying at $7^{\circ}C$, the driving force for dehumidification was lower than under other drying conditions, which resulted in a lower drying rate. There were little color differences between the drying methods and temperature. Squid dried by cold air-drying had better mechanical texture and sensory qualities than with other drying methods. In addition, the cold air drying method maintained superior quality in terms of the contents of amino acids, taurine, EPA, DHA, other fatty acids and a low TBA value than the other drying methods.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.242-247
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• 2009

The present study has been conducted to reduce the cold air drying rate. According to the cold air drying method, the quality-excellent product could be made and there would be little change of color, taste and smell. As compared with the hot air drying, the cold air drying equipment has the superior dehumidification in a constant drying zone. However, in a falling drying zone that equipment is not energy-efficient because the drying period could be longer by the dehumidificated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1573-1579
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• 2004

This study was conducted to develop intermediate material for new processed food from sweet pumpkin. Osmotic dehydration was carried out as pretreatment before drying. After the sweet pumpkins were pretreated under optimized osmotic dehydration conditions, they were dried by three drying methods (hot air drying, vacuum drying and cold air drying). The moisture contents of dried sweet pumpkin products by osmosis treatment (sucrose) and hot air drying, vacuum drying, and cold air drying were 14.48, 14.09 and 13.87%, respectively. Cold air drying preserved more vitamin C content and showed lower color difference than hot air drying and vacuum drying. As a result of microscopic analysis, cold air dried sweet pumpkin was observed regular tissue, while hot air and vacuum dried sweet pumpkins were observed a cell collapse following the loss of water.

• Food Science and Preservation
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• v.22 no.1
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• pp.56-62
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• 2015

In this study, the quality characteristics of different drying methods of Aronia melanocarpa, which contains large amounts of bioactive substances, were investigated for the improvement of their practical use. During the drying period, the weight reduction was the highest with vacuum freeze drying (81.6%). The water content was reduced to the maximum level when vacuum freeze-drying was used. With regard to the color value measurement results, there were no significant differences in the $L^*$ value. Values of $a^*$ and $b^*$ were increased in vacuum freeze drying and cold air drying, but decreased in hot air drying. The hardness was increased dramatically after 36 hours of hot air drying, while with cold air drying, it increased slowly until 132 hr and increased rapidly after 132 hr. The dried yield was the highest with cold air drying (24.2%). As for the general component analysis results of Aronia melanocarpa, the moisture content was the lowest, and the crude protein and crude fat contents were the highest with vacuum freeze drying. No difference in pH value was shown among the dried Aronia melanocarpa obtained from the different drying methods, but the sugar content was the highest with vacuum freeze drying. The mineral content was the highest with cold air drying, and K, Ca, Mg, and Na were the major minerals. The free sugar content of dried Aronia melanocarpa was found to be 5.92~20.59 g/100 g, and the highest free sugar content was found with vaccum freeze drying.

• Food Science and Preservation
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• v.23 no.7
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• pp.1018-1025
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• 2016

To investigate biological activities in Aronia melanocarpa various drying methods were employed such as vacuum freeze drying, hot air drying and cold air drying. DPPH radical scavenging activity and ABTS radical scavenging activity of vacuum freeze dried Aronia melanocarpa was higher than hot and cold air dried Aronia melanocarpa. Vacuum freeze drying method showed the greatest contents of total phenol (15.34 g GAE/100 g), flavonoid (3.10 g GE/100 g) and tannin (2.46 g TE/100 g). Total anthocyanin content decreased to 163.52 mg C3G/100 g and 50.15 mg C3G/100 g for hot and cold air drying, respectively. Vacuum freeze-dried method increased the total anthocyanin content (743.09 mg C3G/100 g) when compared with fresh Aronia melanocarpa (163.52 mg C3G/100 g). Total proanthocyanidin content of vacuum freeze dried Aronia melanocarpa has increased to 6.21 g CE/100 g more than eight times compared with fresh Aronia melanocarpa (0.71 g CE/100 g). Chlorogenic acid and neochlorogenic acid content of vacuum freeze dried Aronia melanocarpa were higher than hot air dried and cold air dried Aronia melanocarpa, increasing about three times compared with fresh Aronia melanocarpa. These results suggested that vacuum freeze drying is optimal drying method to enhance biological activities in Aronia melanocarpa.

• Food Science and Preservation
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• v.13 no.1
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• pp.37-42
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• 2006

In recent, Kimchi is produced in the scale of industry, Consumers show increased demand of safety and high quality and hygienic process control. So, sun drying, hot air drying and cold air drying methods were investigated to compare the demand Sun drying took 96 hrs, hot air drying took 4 hrs at $70^{\circ}$ and cold air drying took 102 hrs at $10^{\circ}C$ in removing water to $90\%$ from radish. Brownness of radish was expressed as absorbance. Absorbance were 0.20, 2.04 and 1.87 and also Vit-C contents were 0.14 mg/g, 0.12 mg/g and 0.096 mg/g in dried radish according to cold air drying, hot air drying and sun drying, respectively. From overall experimental results, cold air drying method was found as superior drying method to other drying methods.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.62-69
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• 2017

Because the moist foods like anchovy were appeared lower quality by hot air that occurred the lipid oxidation, the drying system by using the cold air has been used widely. This study has been carried out on the performance improvement according to arrangement angle of baffle and location of air duct in the cold air dryer. The main parameters in this study are the arrangement angles which are without, $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ and $40^{\circ}$, and the locations of air duct are without, front, center and back. For this study we have conducted the numerical analysis method using fluent in order to obtain the optimal condition of the drying performance. As the arrangement angle of baffle is increased, the relative humidity is proportionally decreased, the value at $40^{\circ}$ is 42.2% that indicate the reduction of about 4% than without it. After the air duct was installed, the decreased relative humidity is showed within 1%, therefore, the effect of air duct for improving the dry capacity is more large than the arrangement angle of baffle. Finally, we have obtained the optimal conditions that the arrangement angle is $40^{\circ}$ with the air duct for a cold air dryer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.192-197
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• 2000

To develop plain dried products of large anchovy, Engraulis japonica, lipid oxidation during drying of large anchovy and optimal drying condition were investigated. The moisture contents of large anchovy on 7 hrs dryness were $ 9.0{\%},\;34.0{\%},\;38.0{\%} and\;38.8{\%}\;in\;60^{\circ}C$ hot-air drying (wind velocity, 1.4m/sec), $40^{\circ}C$ hot-air drying (wind velocity, 1.4 m/sec), sun drying($30{\pm}5^{\circ}C$) and $20^{\circ}C$ cold-air drying (wind velocity, 3.1 m/sec), respectively. The cold-air drying depressed remarkably the lipid oxidation of large anchovy during drying, resulting from AV, POV, COV and the formation of browning pigment. The fatty acid composition of large anchovy was $35.8{\%} in saturates, 20.0{\%} in monoenes and 44.2{\%}$ in polyenes. Saturates and monoenes were increased in proportion to the increase of drying time, while polyenes were decreased. The contents of 20 : 5 and 22 : 6 of polyenes were decreased remarkably in proportion to the progress of lipid oxidation, while 14 : 0, 16 : 0, 16 : 1 and 18 : 1 of saturates and monoenes were increased. The changes in fatty acid compositions by drying conditions were remarkably clarified in sun drying, followed by $60^{\circ}C$ hot-air drying $40^{\circ}C$ hot-air drying and $20^{\circ}C$ cold-air drying in order.

• Food Science and Preservation
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• v.19 no.4
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• pp.485-491
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• 2012

This study was conducted to investigate the pH, soluble solid contents, color difference, mineral contents, free sugar contents, and sensory quality of infrared- and cold-air-dried peaches. The pH, soluble solid contents, and free sugar contents of the infrared-dried peaches were higher than those of the cold-air-dried peaches. In the Hunter's color value, the L and ${\Delta}E$ values of the infrared-dried peaches were higher than those of the cold-air-dried peaches; but the a and b values of the cold-air-dried peaches were higher than those of the infrared-dried peaches. The major organic acids of the dried peaches were citric acid, malic acid, and oxalic acid. The minerals with the highest to lowest contents, in that order, were K, Mg, Ca, Na, Fe, Zn, Cu, and Al. The mineral contents of the cold-air-dried peaches were higher than those of the infrared-dried peaches. The appearance and taste of the infrared-dried peaches were better than those of the cold-air-dried peaches. These results indicate that infrared drying is the effective drying method for the production of high-quality dried peaches.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.5
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• pp.208-215
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• 2016

This study was conducted to improve the performance of low-temperature vacuum dryer by applying desiccant to cold trap. Performance evaluation was carried out using several desiccants. The amounts of absorption and diffusivity were measured based on analytic model. Results of desiccant performance evaluation revealed that silica-gel had the most excellent performance for conditions of low-temperature vacuum drying process. Silica-gel was applied to cold trap for evaluating the drying performance. The experiment results showed that the drying time was extended as the thickness of sample was increased due to increased heat and mass transfer resistance of drying sample. In addition, as heating plate temperature was increased, drying time was decreased due to increased evaporation pressure of drying sample. Furthermore, drying time with desiccant was decreased approximately 20% than that without desiccant.