• Food Science and Preservation
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• v.6 no.1
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• pp.61-65
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• 1999

This study was carried out to investigate change in the components according to drying methods of jujube. Raw jujube was dried with five methods such as sun-drying, hot-air drying after pretreated with sunlight, blanching, microwave treatment, respectively. The contents of soluble sugar and protein in sun-dried jujube were higher than those of other drying methods. The free sugars of dried jujube were consisted of sucrose, glucose and fructose. And the contents of free sugar was not different by drying methods. The major organic acids of dried jujube were oxalic acid, citric acid and malic acid. The contents of glutamic acid, glycine and alanine were higher than those of other amino acids, and the content of each amino acid was not different by drying methods.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1998.12a
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• pp.297-301
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• 1998

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.207-210
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• 1982

For the removal of initial water content in cuttlefish, the effects of fixed-bed drying condition on the drying rate were investigated, with following results. 1. The drying rate of cuttlefish dried at fixed-bed condition was also faster than that at natural convection type or hot air dryer.2. By controlling air temperature and its direction to cut-and-peeled sample the drying time can be reduced to 2 hrs. 3. Shirai's equation and Arrhenius' law were applicable to fixed-bed dried cuttlefish. Drying rate constant (k) by Shirai's equation, and Arrhenius' plot were as shown in Table 3, 4 and Fig.3, respectively.

• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.742-746
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• 2013

This study was conducted to investigate the effect of different steaming and drying temperature conditions on the physicochemical characteristics of pumpkin powder. All the samples were steamed for 30 or 60 s and then were dried using hot air at 40, 50, 60, and $70^{\circ}C$. The moisture content decreased with an increase in the hot-air drying temperature, while the soluble solid content and yield increased. The color values, L, a, and b of the pumpkin powder decreased with increasing hot-air drying temperature. The pumpkin powder, which was steamed for 60 s had the highest water absorption and water solubility indexes. The carotenoid content of pumpkin powder was mostly destroyed with the increase in the steaming and drying temperatures. The total sugar and reducing sugar contents increased with increasing steaming and drying temperatures. Thus, the steaming and dehydration temperature conditions influenced the physicochemical characteristics of the pumpkin powder.

• Korean Journal of Food Science and Technology
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• v.26 no.2
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• pp.147-151
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• 1994

Hydrogen donating activities(HDA) of solvent extracts of Hololeion maximowiczii roots which were treated with freeze drying, hot air drying and hot air drying after steam blanching were investigated by the method of ${\alpha},{\alpha}'$-diphenyl-${\beta}$-picrylhydrazyl(DPPH). Hydrogen donating activity of hot air drying after steam blanching group showed the highest activity among three drying methods. Among the extracts of freeze dried root extracted with various solvents, color intensity at 420 nm of aqueous extract was highest, but hydrogen donating activity was shown in order of 50%, ethyl alcohol, methyl alcohol, water extracts. By heating the powder of freeze dried root at $100^{\circ}C$, color intensity of its water extract was decreased until 20 min, thereafter it was increased slowly but hydrogen donating activity was rapidly increased until 30 min. Hydrogen donating activity at the concentration of 6.05 mg/ml of 50% alcohol extract was similar to that of ${\alpha}-tocopherol$ at the concentration of $2{\times}10^{-4}M$. Comparison of hydrogen donating activity of the inner and outer solution after dialysis of water extract showed that the outer solution had a stronger hydrogen donating activity than those of the inner one.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.389-395
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• 2016

Purpose: Drying is one of the most widely used methods for preserving agricultural products or food. The main purpose of drying agricultural products is to reduce their water content for minimizing microbial spoilage and deterioration reaction during storage. Methods: Although numerous drying methods are successfully applied to dehydrate various agricultural products with little drying time, the final quality of dried samples in terms of appearance and shape cannot be guaranteed. Therefore, based on published literature, this review was conducted to study the drying characteristics of various agricultural products when different drying methods were applied. Results: An increase in the drying power of sources-for example, increase in hot air temperature or velocity, infrared or microwave power-and the combination of drying power levels can reduce the drying time of various agricultural products. In addition, energy efficiency in drying significantly relies on the compositions of the dried samples and drying conditions. Conclusions: The drying power source is the key factor to control entire drying process of different samples and final product quality. In addition, an appropriate drying method should be selected depending on the compositions of the agricultural products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.716-722
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• 2004

This study investigated the quality characteristics of sponge cakes with addition of mushroom (Pleurotus eryngii) powders prepared by different drying methods, hot air (HDMP: hot air dried mushroom powder) and freeze drying (FDMP: freeze dried mushroom powder). The specific gravities, viscosity, height, specific volume, color, texture and sensory evaluation of bread dough containing 3%, 5% and 7% mushroom powders were measured. The specific gravity and viscosity tended to increase according to the addition of mushroom powder. The height and specific volume tended to decrease according to the addition mushroom powder. Substituting mushroom powder for flour also resulted in decreased yellowness and lightness and increased redness of the cake crust. The hardness of cakes containing mushroom powders was higher than tat of control without mushroom powders. The color of cake crust became darker as the amount of mushroom powders increased. The results of sensory evaluation by QDA (quantitative descriptive analysis) to compare two different drying methods showed that overall acceptalility of sponge cakes containing 3% and 5% mushroom power were higher than that of control without mushroom powder.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.111-115
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• 2009

Carrots were dried using 30, 50, and 80% polyethylene glycol (PEG) or maltodextrin as a dehydrating agent, and the dried carrots were compared with the freeze dried and hot-air dried in terms of rehydration ratio, color, carotene content, and sensory evaluation. The amount of moisture loss during drying of carrots using PEG or maltodextrin increased with increasing concentration of dehydrating agent. Rehydration ratio as well as carotene content of the PEG-treated carrots were greater than those of freeze-dried or hot-air dried carrots. Regarding color and sensory evaluation of the dried carrots, the PEG-treated and maltodextrin-treated carrots were better than freeze-dried or hot-air dried carrots. These results suggest that drying of carrots using PEG or maltodextrin is a very efficient method because of its good rehydration capacity and minimal destruction of nutrients and cell structure.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.6
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• pp.479-484
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• 2001

The absorption characteristics of persimmon powder related to different drying methods and various storage temperatures was investigated. The physical properties of persimmon powder by different drying methods displayed the largest amount of porosity in the freeze-dried sample, and the smallest in hot air dried sample. Equilibrium moisture was reached in 6 days. Monolayer moisture contents were predicted to 0.09687~0.19712(freeze drying), 0.07820~0.18617(vacuum drying) and 0.07715~0.18056(hot air drying) g H2O/g solid respectively using the BET equation. BET equation for isothermal absorption curve showed over 0.95 R-square for all dried methods. Monolayer moisture contents were increased as storage temperature was incremented because water molecular movement was more active and there was a greater chance to clash with the absorption surface area.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.145-150
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• 2009

In this study, characteristics of microwave and convective drying are studied by using a multiphase porous media model. Temperature and moisture profiles for hot-air convective heating and microwave heating of 1-D porous media with varying time and space are numerically investigated. This result shows the microwave drying method is more effective than the convective drying method. Comparing to convective drying, microwave drying can increase temperature and evaporation rate significantly since microwave generates internal heat and increases internal pressure, which results in moisture movement toward the surface on which moisture is vaporized.