• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.342-349
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• 1982

Filefish muscle in the form of thin plate $(5{\times}10{\times}0.4\;cm)$ was dried in a forced air dryer at $47.5^{\circ}C$ to study the relation between dehydration mechanism and water activity. The dryer was designed in such a way that the temperature, relative humidity and velocity of air could be controlled. The whole dehydration process of the filefish muscle was divided into two different drying rate periods, constant and falling rate period. During the constant drying rate period, the drying rate was proportional to the square root of air velocity under the conditions of constant temperature and relative humidity of air. The falling rate period was further divided into two different falling drying rate periods, first and second falling rate period. The first falling rate period was an unsaturated surface drying period caused by partial unsaturation of the drying surface with capillary condensed free water diffused from the internal part of the filefish muscle. At this stage he drying rate was mainly dependent on the relative humidity at constant air temperature, and case-hardening phenomenon started at the end of this stage. The moisture content and the water activity at which the second falling rate period started were not constant, because the drying rate of the first falling rate period was strongly dependent on the air humidity. The second falling rate period was again divided into two drying rate periods, former and latter period. The drying rates of both of these periods were independent on the external air humidity. During the former period of the second falling rate period, the dehydration was proceeded by diffusion and vaporization of capillary condensed free water in filefish muscle. The diffusion coefficient of water was $2.89{\times}10^{-10}m^2/sec\;at\;47.5^{\circ}C$. At this stage, the case-herdening continued until the water activity reduced to 0.7. The latter period of the second falling rate period started at the water activity of 0.45. The dedydration was proceeded by diffusion and vaporization of bound water, which adsorbed in multimolecular layers, through the hardened drying surface. The number of molecular layers was 4, and the diffusion coefficient of water during this stage was $4.38{\times}10^{-11}m^2/sec\;at\;47.5^{\circ}C$.

• Korean Journal of Materials Research
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• v.34 no.2
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• pp.79-84
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• 2024

Thin films of yttria-stabilized zirconia (YSZ) nanoparticles were prepared using a low-temperature deposition and crystallization process involving successive ionic layer adsorption and reaction (SILAR) or SILAR-Air spray Plus (SILAR-A+) methods, coupled with hydrothermal (175 ℃) and furnace (500 ℃) post-annealing. The annealed YSZ films resulted in crystalline products, and their phases of monoclinic, tetragonal, and cubic were categorized through X-ray diffraction analysis. The morphologies of the as-prepared films, fabricated by SILAR and SILAR-A+ processes, including hydrothermal dehydration and annealing, were characterized by the degree of surface cracking using scanning electron microscopy images. Additionally, the thicknesses of the YSZ thin films were compared by removing diffusion layers such as spectator anions and water accumulated during the air spray plus process. Crack-free YSZ thin films were successfully fabricated on glass substrates using the SILAR-A+ method, followed by hydrothermal and furnace annealing, making them suitable for application in solid oxide fuel cells.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.422-427
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• 1994

The quality of salted and semi-dried mackerel prepared by cold osmotic dehydration using a high osmotic pressure resin during storage at $5{\pm}1^{\circ}C$ was evaluated. The moisture contents in salted and semi-dried mackerel decreased in. range of 4 during storage. The brown pigment formation content and peroxide value of salted and semi-dried mackerel prepared by osmotic dehydration were more lower than those of salted and semi-dried mackerel prepared by traditional drying methods such as sun-drying, hot-air drying and cold air drying. The viable cell count and histamine contents of cold osmotic dried products were much lower and revealed a tendency to increase during storage, but even these values after storage of 15 days showed that the salted and semi-dried mackerel was safety in respect of food sanitation. The ratio of saline soluble nitrogen to total nitrogen in cold osmotic dried products were higher than that of traditional dried products during storage. Judging from the results of chemical and sensory evaluation, shelf-life of salted and semi-dried mackerel by cold osmotic drying were more longer than that of salted and semi-dried mackerel prepared by traditional drying.

• 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.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.468-474
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• 1993

A dehydrating sheet comprises polymeric water absorber. which are packed in a semipermeable cellophane film bag allowing selective permeation of water. This sheet dehydration is quite different from conventional drying method such as sun drying, hot-air blast drying and cold air blast drying in a sense that samples are dried without heat treatment. As a part of the studies to develope a new processing method for effective utilization of dark muscle fishes, the preparation of a good quality salted and semi-dried mackerel by the dehydrating sheet was attempted. The dehydration time for preparation of a salted and semi-dried mackerels containing approximately equal moisture content were revealed $180{\sim}510min$ in conventional drying method and $90{\sim}160min$ in this sheet dehydration, respectively. The moisture and histamine contents of those salted and semi-dried mackerels were $59.4{\sim}62.4%$ and $2.5{\sim}3.6 mg/100g$, respectively. The changes in peroxide value, fatty acid composition, brown pigment formation, myofibrillar protein solubility and Ca-ATPase activity during processing of the salted and semi-dried mackerel prepared by the sheet dehydration were more lower than those of products prepared by conventional drying methods. Therefore, these result showed that the quality of a salted and semi-dried mackerel prepared by the sheet dehydration was imperial to that of those products by conventional drying method.

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.225-230
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• 2008

Onion slices were dehydrated in a single layer at drying air temperatures ranging from $50{\sim}70^{\circ}C$ in a laboratory scale convective hot-air dryer at an air velocity of 0.66 m/s. The effect of drying air temperature on the drying kinetic characteristics were determined. It was found that onion slices would dry within $210{\sim}460\;min$ under these drying conditions. Moisture transfer during dehydration was described by applying the Fick's diffusion model and the effective diffusivity changed between $1.345{\times}10^{-8}$ and $2.658{\times}10^{-8}\;m^2/s$. A non-linear regression procedure was used to fit 9 thin layer drying models available in the literature to the experimental drying curves. The Logarithmic model provided a better fit to the experimental drying data as compared to other models. Temperature dependency of the effective diffusivity during the hot-air drying process obeyed the Arrhenius relationship with estimated activation energy being 31.36 kJ/mol. The effect of the drying air temperature on the drying model constants and coefficients were also determined.

• Preventive Nutrition and Food Science
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• v.14 no.4
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• pp.367-372
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• 2009

Apple, persimmon, and strawberry slices were dehydrated after treating with 30, 50, and 80% (w/w) maltodextrin solution. The dried apple, persimmon, and strawberry slices were compared with hot air-dried and freeze-dried samples in terms of rehydration ratio, ascorbic acid, color, and sensory evaluation. The rehydration ratio of maltodextrin-treated samples was greater than that of hot-air or freeze-dried samples. Maltodextrin-treated samples had higher content of ascorbic acid than other dried samples. Additionally, maltodextrin-treated apple, persimmon, and strawberry slices had better color and sensory evaluations than those of freeze-dried or hot-air dried samples. These results suggest that, compared to other drying methods, dehydration of apple, persimmon, and strawberry slices using maltodextrin is very efficient, resulting in good rehydration capacity, minimal destruction of ascorbic acid, and good color and sensory evaluation.

• Journal of Applied Biological Chemistry
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• v.56 no.1
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• pp.19-22
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• 2013

Plum (Prunus salicina L.) slices were dehydrated with red algae extract (RAE) at a concentration of 30% (w/w), and the dried samples were compared with maltodextrin (MD)-treated and hot-air dried samples in terms of physicochemical properties such as rehydration ratio, ascorbic acid, microstructure, and color. The rehydration ratios and colors of RAE-treated plum slices were better than those of MD-treated and hot-air dried samples. The ascorbic acid contents of RAE-treated samples were higher and their microstructures were finer than those of MD-treated or hot-air dried samples. These results suggest that plum slices can be dehydrated with RAE without loss of quality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.7
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• pp.1230-1236
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• 2004

This study was conducted to investigate the changes in physical properties of the Neungee (Sarcodon aspratus) during dehydration and rehydration. The drying of the sample was completed within 4 hours at 5$0^{\circ}C$ with the air velocity of 1.5 m/s. The reduction in the thickness of the sample were two-fold compared with those in the surface area of the sample. During the drying period, the values of compression distance, break down, deformation rate, distortion, alleviation rate and softness decreased, whereas the values of hardness and alleviation time increased. However, the values of surrender were not changed. The color of the sample during the drying was changed to black with decreased L, a, and b values. The rehydration rate increased rapidly during first 60 min and remained constant after that. The recovery ratio after rehydration of the dried sample was about 30％ and the rheological properties recovered about 44％.

• Nutrition Research and Practice
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• v.6 no.2
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• pp.126-131
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• 2012

The purpose of this study was to determine the effects of beverage temperature and composition on weight retention and fluid balance upon voluntary drinking following exercise induced-dehydration. Eight men who were not acclimated to heat participated in four randomly ordered testing sessions. In each session, the subjects ran on a treadmill in a chamber maintained at $37^{\circ}C$ without being supplied fluids until 2% body weight reduction was reached. After termination of exercise, they recovered for 90 min under ambient air conditions and received one of the following four test beverages: $10^{\circ}C$ water (10W), $10^{\circ}C$ sports drink (10S), $26^{\circ}C$ water (26W), and $26^{\circ}C$ sports drink (26S). They consumed the beverages ad libitum. The volume of beverage consumed and body weight were measured at 30, 60, and 90 min post-recovery. Blood samples were taken before and immediately after exercise as well as at the end of recovery in order to measure plasma parameters and electrolyte concentrations. We found that mean body weight decreased by 1.8-2.0% following exercise. No differences in mean arterial pressure, plasma volume, plasma osmolality, and blood electrolytes were observed among the conditions. Total beverage volumes consumed were $1,164{\pm}388$, $1,505{\pm}614$, $948{\pm}297$, and $1,239{\pm}401$ ml for 10W, 10S, 26W, and 26S respectively ($P$ > 0.05). Weight retention at the end of recovery from dehydration was highest in 10S ($1.3{\pm}0.7kg$) compared to 10W ($0.4{\pm}0.5kg$), 26W ($0.4{\pm}0.4kg$), and ($0.6{\pm}0.4kg$) ($P$ < 0.005). Based on these results, carbohydrate/electrolyte-containing beverages at cool temperature were the most favorable for consumption and weight retention compared to plain water and moderate temperature beverages.