• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.25-31
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• 2004

Characteristics of good-quality red pepper powder produced using $N_{2}$-circulated low-temperature drying method were compared with those made through conventional sun and hot-air drying methods. Kimchi and kochujang were prepared with different types of red pepper powder, and their physicochemical and sensory properties were compared. Results revealed Hunter L (lightness), a (redness), and b (yellowness) values of $N_{2}$-circulated low temperature-dried red pepper were highest. Absorbance of crude capsanthin in hot air-dried red pepper powder ($0.584{\pm}0.001$) was significantly lower than sun-dried ($0.848{\pm}0.001$) and $N_{2}$-circulated low temperature-dried products ($0.832{\pm}0.002$. Use of $N_{2}$-circulated low-temperature drying method resulted in the highest amounts at reducing sugar and total vitamin C. Capsaicin content of $N_{2}$-circulated low temperature-dried products were higher than hot air-dried ones. The aL values of kochujaug made with sun-and low temperature-dried red peppers were higher than that of kochujang made with hot-dried red peppers. Physicochemical and sensory evaluation results showed red pepper powders made using $N_{2}$-circulated low-temperature drying method have the best quality among all samples tested.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.107-110
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• 1982

Fixed bed drying method was selected to reduce the initial drying time of squid and the effects of drying air temperature and bed height on the drying rate were investigated, with following results. 1. The drying rate in the fixed bed dryer was faster than that of natural convection type dryer heated indirectly and that of hot air dryer heated directly. 2, Shirai-equation was applicable to squid being dried. Using the equation, drying rate constant obtained was as shown in table 1.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.3
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• pp.232-240
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• 2019

Approximately 80% of the world's sea cucumbers Apostichopus japonicas are processed into dried sea cucumbers. The hot air-drying method is currently used in industry, but it has many problems, such as a short drying time, severe browning, high nutrition loss, and low recovery. In this study, the moisture absorption rate, dry recovery rate, and lipid nutrient composition of sea cucumber dried by heat pump decompression and with a hybrid dryer were investigated. The moisture absorption rates for hybrid-dried sea cucumbers at 24, 48, 72, 96, and 120 h were 241.3%, 427.7%, 652.0%, 721.0%, and 742.2%, respectively. The moisture absorption rates for hot air-dried sea cucumbers were 155.8%, 240.0%, 390.3%, 655.5%, and 667.4%, respectively. Thus, moisture absorption was faster and greater with hybrid drying than with hot air drying. The dry recovery rate at 24 h was greater for hybrid-dried sea cucumber (70.7%) than for hot air-dried sea cucumber (59.8%). Saturated fatty acid contents of the hybrid- and hot air-dried sea cucumbers were 30.0% and 37.5%, respectively. Moreover, greater ${\Sigma}n-3$ polyunsaturated fatty acid content was found in hybrid-dried sea cucumber (15.8%) than in hot air-dried sea cucumber (11.7%).

• Food Science and Preservation
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• v.12 no.5
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• pp.442-448
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• 2005

To develop efficient drying method, one of important process in manufacturing of Saengsik, uncooked food, the change of physicochemical characteristics and functional component contents of cereals dried by various drying methods was investigated. The proximate composition and dietary fiber content of rice, brown rice, glutinous rice and barley showed little changes during hot-air drying (50$\circC$, 55$\circC$, 60$\circC$) and freeze-drying. Yellowness(b) value of hot-air dried products was higher than one of freeze-dried products. The content of niacin was 0.77 mg% in milled rice, 1.84 mg% in brown rice, 0.68 mg% in glutinous rice, 1.00 mg% in barely dried by hot-air at 60$\circC$ and was lower than those of other samples. $\beta$-glucan content in barely was not changed by hot-air drying and freeze-drying method. In conclusion, hot-air drying would be recommended for barley having $\beta$-glucan, a kind of functional components and freeze-drying should be used for raw materials having heat-labile components such as niacin.

• The Korean Journal of Food And Nutrition
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• v.31 no.6
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• pp.933-939
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• 2018

The objective of this study was to determine the effects of drying methods on the quality characteristics and antioxidant activities of pumpkin (Cucurbita moschata Duch.). Pumpkins were dried naturally ($25^{\circ}C$), hot-air drying ($60^{\circ}C$), and throgh freeze drying ($-40^{\circ}C$) methods. The moisture activities were highest in the freeze dried group. The soluble solid showed no significant differences among all groups. The pH was highest in the freeze dried group. The L values were increasing in freeze dried group, whereas the b values were increased in hot-air dried group. The free sugar was highest in freeze dried group. The DPPH radical scavenging activity of hot-air dried group was higher than those of the other groups. The ABTS radical scavenging activities were highest with hot-air dried group and freeze dried group. It was established that hot-air dried group is the most effective drying method for the production of high quality dried pumpkin.

• Food Science and Preservation
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• v.7 no.4
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• pp.389-394
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• 2000

To utilize deteriorated sweet persimmon(Diospyros kaki T.) effectively, this study was investigated about the effective (Dying method of the powder. Chemical components, minerals, fatty acids and amino acids of hot-air dried and freeze dried conditions were determined Sample conditions used on analysis as follow; pretreatments of hot-air dry and freeze dry were soft, soft+peel, mixer, mixer+peel. The contents of crude protein, crude lipid, crude ash of hot-air dry were 0.9-1.1%,15.0-39.0% and 2.3-3.3%, respectively. And those of freeze dry were 1.3-2.2%, 27.-49.0% and 2.5%, respectively. Potassium, magnesium, phosphorus, calcium and sodium content in hot-air dry and freeze dry were high. Other minerals were less than 3.00ppm in all conditions. The major fatty acid contents were detected capric acid(C$\^$10:0/), lauric acid(C$\_$l2:0)/, tridecanoic acid(C$\_$13:00/), palmitic acid(C$\_$l6:00/), palmitoleic acid(C$\_$l6:1/), oleic acid(C$\_$18:1), linoleic acid(C$\_$18:2/), linolenic acid(C$\_$18:3/). The essential amino acids such as aspartic acid, threonine, serine, glutamic acid, glycine, alanine, valine, methirmine, isoleucine, leucine, tryosine, phenylalanine, histidine, lysine, arginine in freeze dry were contained richly. On the basis of chemical analysis, hot-air dry method will have to supply the additional different method, because simple hot-air dry method was shorten the dry time but had many problems. Therefore, the effective drying method considering changed color and nutrition was shown freeze dry method.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.314-322
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• 2017

Purpose: This study was conducted to investigate the hot air drying characteristics of squash slices depending on the drying conditions (input air velocity, input air temperature, and sample thickness). Methods: The developed drying system was equipped with a controllable air blower and electric finned heater, drying chamber, and ventilation fan. Squash (summer squash called Korean zucchini) samples were cut into slices of two different thicknesses (5 and 10 mm). These were then dried at two different input air temperatures (60 and $70^{\circ}C$) and air velocities (5 and 7 m/s). Six well-known drying models were tested to describe the experimental drying data. A non-linear regression analysis was applied to determine model constants and statistical indices such as the coefficient of determination ($R^2$), reduced chi-square (${\chi}^2$), and root mean square error (RMSE). In addition, the effective moisture diffusivity ($D_{eff}$) was estimated based on the curve of ln(MR) versus drying time. Results: The results clearly showed that drying time decreased with an increase in input air temperature. Slice thickness also affected the drying time. Air velocity had a greater influence on drying time at $70^{\circ}C$ than at $60^{\circ}C$ for both thicknesses. All drying models accurately described the drying curve of squash slices regardless of slice thickness and drying conditions; the Modified Henderson and Pabis model had the best performance with the highest R2 and the lowest RMSE values. The effective moisture diffusivity ($D_{eff}$) changes, obtained from Fick's diffusion method, were between $1.67{\times}10^{-10}$ and $7.01{\times}10^{-10}m^2/s$. The moisture diffusivity was increased with an increase in input air temperature, velocity, and thickness. Conclusions: The drying time of squash slices varied depending on input temperature, velocity, and thickness of slices. The further study is necessary to figure out optimal drying condition for squash slices with retaining its original quality.

• Korean journal of food and cookery science
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• v.18 no.2
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• pp.173-178
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• 2002

Fresh Shiitake mushrooms were irradiated by UV-B or dried by using hot air to increase the vitamin D$_2$content. Vitamin D$_2$content was determined by high-performance liquid chromatography Irradiating the inside of the mushroom cap was more effective in increasing vitamin D$_2$content than irradiating the outside of the mushroom cap. Irradiation of UV-B at 0, 2.5, 5.0, 7.5 and 10 J/㎠ increased the content of vitamin D$_2$in the mushroom to 21.51, 120.78, 144.38, 168.08, and 187.69 $\mu\textrm{g}$/g, respectively. Vitamin D$_2$content of Shiitake mushrooms with irradiation of 10 J/㎠ decreased from 187.69 to 98.78 $\mu\textrm{g}$/g by 6 hours of hot-air drying. When three kinds of drying method (UV-B irradiation followed by hot-air drying, hot-air drying, and sunlight drying) were compared, the combination of UV-B irradiation and hot-air drying was the most effective in terms of increasine the vitamin D$_2$content in the mushroom.

• Textile Coloration and Finishing
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• v.21 no.4
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• pp.23-32
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• 2009

The objective of this study is to investigate the efficacy of leaf powder colorants as substitutes for traditional indigo dyeing. Leaf powder colorants were prepared by hot air($50^{\circ}C$) and room temperanrre($25^{\circ}C$) drying methods from fresh leaves. The presence of indigo in the leaf powder colorants was confirmed by UV/Visible absorption spectra. All the powder colorants showed broad absorption at 602 nm as same as synthetic indigo. Dyeing was done by reduction method with sodium hydrosulfite and sodium hydroxide. Leaf powder colorants produced blue color on silk fabrics, showing similar color to the one dyed traditionally with fresh juice extract. The powder colorants prepared at room temperature drying were more stable for long term storage than that prepared by hot air drying. Thus, the powder colorants prepared by room temperature drying was reduced and dyed in one-step process without sodium hydroxide in the dyebath for further investigate dyeing properties. K/S value of the fabric dyed without sodium hydroxide was much higher than one dyed with sodium hydroxide. Regardless of the addition of sodium hydroxide, rubbing fastness was fairly good showing above 4 rating. Fastness to dry cleaning and light of the fabrics dyed without sodium hydroxide were mote higher than that dyed in alkaline condition.

• 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.