• Korean Journal of Medicinal Crop Science
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• v.10 no.1
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• pp.24-28
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• 2002

Effect of pretreatment processing (peeling time, drying temperature, sample type) on the quality of hot air drying peony roots was investigated. Peony roots were peeled for 0, 10, 20, 30, 60, 90 and 120 minute in the peeling machine after water washing. Sample types were whole or cut (thickness of 3mm). Temperatures of hot air drying were 30, 40, 50 and $60^{\circ}C$ The level of water contents in dried sample was $14{\sim}15%$. Drying time was muth reduced as the peeling time, cutting sample types and higher temperature. Contents of paeoniflorin were maintained highest amount (3.48%) in the non-peeling cut sample dried at $30^{\circ}C$ and lowest amount (2.29%) in the 120min-peeling whole one dried at $60^{\circ}C$. Skin color of dried peony roots was heavily discolored in the sample of non-peeling whole type dried at $60^{\circ}C$ and the color was dark brown $({\Delta}E\;was\;46.1)$. When considering shortening of drying time, preservation of active compounds and maintenance of color, the best pretreatment method of drying in peony roots was non-peeling, cut type processing.

• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.124-130
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• 2021

Dental prosthesis translucency importantly contributes to aesthetic outcomes. The purpose of this study was to investigate the effect of drying time and zirconia coloring agent type on translucency. For the experiment, 90 circular specimens were fabricated for each zirconia block. Then, zirconia specimens were treated with a coloring agent for 180 seconds and dried for 0 seconds (undried), 30 seconds (intermediate dry), or 30 minutes (complete dry). Then, a specimen was placed on a black standard tile or a white standard tile, and using a standard D65 light source reflected was measured using the light removal method. A total of three repeated measurements were obtained per specimen. One-way ANOVA was used to compare and analyze the relationship between zirconia translucency and drying time. Zirconia and coloring liquid types were significantly associated with translucency (P < 0.001). Although no significant difference was observed with respect to drying time (P > 0.922), zirconia in the completely dried (30 minutes) state was more translucent.

• Korean Journal of Plant Resources
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• v.8 no.2
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• pp.115-125
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• 1995

The moistures, colors and flavors of red pepper were analyzed to observe the changes of the qualities of red pepper with various conditions of drying. The moisture was 11.8%, known as optimal condition for storing red pepper, where dried at $50^{\circ}C$ for 36 and 48 hours. The color of red pepper air-dried at 50% for 48 hours was estimated to be the most execllent in comparison of sun drying and air drying. The optimal absorbances of hexnae extract from red pepper were examined. The ratios between the absorbances at 280nm and at the typical wavelengths of caretenoids(430nm, 450nm, 474nm) were from 2.5-3.4 and these wete also confirmed by the sight of the eye. Hexane fraction showed more peaks of flavors than benzene fraction and both of the two were silylated by with BSTFA to analyze the flavors by GC. CG profiles for the compositions of flavors in red perpper are thought to be useful for extimating the quality of favors in red pepper. Eight flavors including benzene dicarbozylic acid, were identified from red pepper and major components of them were oleic palmitic acids. Drying temperatures and times did not have effects on the changes of specific flavor components but did influenced the compositions of them in red pepper.

• Korean Journal of Medicinal Crop Science
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• v.4 no.4
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• pp.283-287
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• 1996

As a part of studies on the quality control for drying methods in Lycii Fructus. Dried Lycii Fructus were obtained from several treatments to examine the control of the extracts and its physical properties, and also to analyze the inorganic elements and proximate compositions. The results were summerized as follows; the changes of solid matter contents dried at $50^{\circ}C\;for\;4\;hrs\;and\;60^{\circ}C$ for 28 hrs were highest. The changes of Hunter values were 66 in lightness, 5.0 in redness and 51.3 in yellowness, respectively in treatment No. 1. And also the viscosity of treatment No. 1. was some high compared to the other treatment. The desirable drying temperature were at $50^{\circ}C$ for 2hrs in initial and at $60^{\circ}C$ for 24hrs in final temperature and it was the best conditions as a quality, economics and chemical compositions of Lycii Fructus.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.2
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• pp.136-141
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• 2000

This study was conducted to analyze the properties of the roasted dandelion tea prepared after various pre-treatments such as pre-drying, steaming and air blast drying. The dandelion tea was prepared by roasting the pre-treated dandelion leaves and its total yield, pH, soluble solid content, turbidity, browning and sensory value were evaluated. Total yield and soluble solid content were the highest in case of air blast drying. Turbidity and browning degree were similar in all the teas regardless of their pre-treatment including pre-drying, steaming or air blast drying. The best palatability in the sensory evaluation was obtained at the steaming condition for 60 sec without pre-drying. Longer air blast drying time resulted in the increase in the a and b values. turbidity, browning degree, total yield and soluble solid content in the air blast dried tea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.9
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• pp.1314-1320
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• 2011

Vacuum drying was conducted for a steamed pumpkin-sweet potato slab to improve its quality, convenience and preference as snack. Steamed sweet potato was dried from 30 to $60^{\circ}C$ for 12 hr, after which moisture contents, colors, and taste were evaluated. The lowest moisture content was 0.22% upon vacuum drying at $60^{\circ}C$ for 12 hr. Lightness decreased while other color values (a, b and ${\Delta}E$) increased with increasing drying temperature and drying time. Reducing sugar and soluble solid contents ranged from 98.7~268.11 mg/g and $19{\sim}72^{\circ}Brix$, respectively. Sensory score of the sample was the highest when dried at $50^{\circ}C$ for 6 hr. The optimum drying conditions were predicted to be $48.5{\sim}62^{\circ}C$ and 5.1~7.1 hr by response surface methodology.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1126-1134
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• 1996

The physical characteristics changes of carrots during drying were studied to minimize the quality degradation by applying improved drying process and pretreatment method. Physico-chemical properties of the product were analyzed, and then, drying mechanisms were explained by diffusion coefficients and drying models. In hot air drying process, the drying and rehydration efficiencies were high at low relative humidity and high temperature. Browning degree and specific volume also showed similar trend to drying efficiency. Diffusion coefficient, which describes moisture transfer, was also high at low relative humidity and at high temperature. It was verified using. Arrhenius equation that drying process was influenced by temperature. It was also observed during experiment that temperature changes were more effective in drying than relative humidity changes. Quadratic model was the most fittable in explaining the process. As a result of analyzing the experimental data with respect to the drying time, the contents of carotene and moisture could be modeled as a polynomial. As the air velocity increased, drying performance and rehydration efficiency increased.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.561-567
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• 2000

This study was conducted to determine the effect of far infrared-vacuum drying on the quality changes of Pimpinella bracycarpa, such as drying efficiency (weight loss), color differences, browning degrees, rehydration and sensory evaluation. Wehn Pimpinella bracycarpa was dried for designated time at 5$0^{\circ}C$, 6$0^{\circ}C$ and 7$0^{\circ}C$, drying time of far infrared-vacuum drying was decreased more than 17% compared to that of infrared drying. The color changes increased as drying temperature increased and far infrared-vacuum drying made less color changes than infrared drying. Also, the total microbial counts and the number of yeast and mold were gradually reduced as drying temperature increased and drying time was longer, but there was no significant differences in microbial changes among drying methods. The rehydration rates of Pimpinella bracycarpa increased as drying temperature increased and was better at far infrared-vacuum drying than infrared drying. Also, according to the sensory evaluation after rehydration of Pimpinella bracycarpa, the hihger scores were obtained at lower temperature and far infrared-vacuum drying, especially the color was obtained much hihger score in the far infrared-vacuum drying than infrared drying. Thus, the results showed that drying efficiency and stability of rehydration and color changes was increased and the quality deterioration of Pimpinella bracycarpa could be minimized by using far infrared-vacuum drying.