• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.4
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• pp.353-358
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• 1985

Three kinds of aqueous solution of tobacco extracts are used as a new experimental material. It is measured how the operating condition, freezing point, viscosity as fundamental properties have the relation to concentration and temperature of the solution. The results of this study are obtained as follows. 1) The freezing point of the solution $(t_m)$ is presented; $t_m=-{\frac{18.6X}{170-{\frac{X}{100}}(170+18)}}$ 2) The correlation of the viscosity, the temperature and the concentration of the solution is followed; $log_{10{\mu}}={\frac{1585}{T}}+2.11{\frac{X}{100-X}}-5.50$ 3) The ice crystals whose circumference is a toothed wheel are made from high concentrated solution, and the thick plate shaped ones are done from the low concentrated solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.629-636
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• 1991

Yellowtail fishes(Seriola quinqueeradiata) were submitted to the storages using ice-cooling($0^{\circ}C$), partial freezing($-3^{\circ}C$) and freezing $-20^{\circ}C$) method. Changes in the structures of muscle during storage at different temperatures were investigated. The ice-cooling and partial freezing storage caused early decomposition of glycogen granules and mitochondrial inner membrane, but it was accorded to much slower manner comparing with that of ice-cooling storage. The scars of ice crystals were appeared after three days of storage. The number and size of the crystal increased as progressing of the storage. They were circular and mostly located between fibers. When using the freezing storage, glycogen granules were mostly found from the muscle cell even after fourteen days of storage. Mitochonidral inner membrane maintained their integrity. The scars of ice crystals were also found, however, different from those of partial freezing storage. Their existing sites were random and their shapes were irregular. In many cases, they located in the fiber and had keen edges. Fibers were broken mostly at the Z-lines on fourteen days of storage. From these results, it was concluded that partial freezing storage can repress autolytic enzymic action and can reduce the physical damage from ice crystals which is caused by freezing.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1260-1268
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• 2018

To improve fuel performance and specific characteristics of long storage and moving through fuel systems additives should be added in kerosene type aviation turbine fuel (AVTUR) such as antioxidant, fuel system icing inhibitor (FSII), electric conductivity improvers and so on. The dosage of additives has to be analyzed qualitatively and quantitatively due to inspect the quality of abnormal fuel and distinguish other petroleum products. Multi-dimensional GC-MS (MDGC-MS) with Deans switching technique are applied the determination of antioxidant and FSII, which are added with AVTUR containing complex mixture of hydrocarbons. Antioxidant and FSII in the range of 2.5-20 mg/L was quantitatively and qualitatively analyzed using MDGC-MS and the detection limit was about twice as low as that of the 1-dimensional GC-MS results. The method in this study has been higher peak resolution compared with GC-MS and could be simultaneously analyzed different two additives without sample pre-treatment.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.409-422
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• 2022

Two dominant thrips in hot pepper (Capsicum annuum) cultivating in greenhouses are Frankliniella occidentalis and F. intonsa in Korea. This study investigated their overwintering physiology. These two thrips were freeze-susceptible and suppressed the body freezing temperature by lowering supercooling point (SCP) down to -15~-27℃. However, these SCPs varied among species and developmental stages. SCPs of F. occidentalis were -25.7±0.5℃ for adults, -17.2±0.3℃ for pupae, and -15.0±0.4℃ for larvae. SCPs of F. intonsa were -24.0±1.0℃ for adults, -27.0±0.5℃ for pupae, -17.2±0.8℃ for larvae. Cold injuries of both species occurred at low temperature treatments above SCPs. Thrips mortality increased as the treatment temperature decreased and its exposure period increased. F. occidentalis exhibited higher cold tolerance than F. intonsa. In both species, adults were more cold-tolerant than larvae. Two thrips species exhibited a rapid cold hardening because a pre-exposure to 0℃ for 2 h significantly enhanced the cold tolerance to a lethal cold temperature treatment at -10℃ for 2 h. In addition, a sequential exposure of the thrips to decreasing temperatures made them to be acclimated to low temperatures. To investigate the overwintering sites of the two species, winter monitoring of the thrips was performed at the greenhouses. During winter season (November~February), adults of the two species were not captured in outside of the greenhouses. However, F. occidentalis adults were captured to the traps and observed in weeds within the greenhouses. F. occidentalis adults were also emerged from soil samples obtained from the greenhouses during the winter season. F. intonsa adults did not come out from the soil samples at November and December, but emerged from the soil samples obtained after January. To determine the adult emergence due to diapause development, two thrips species were reared under different photoperiods. Adult development occurred in all photoperiod treatments in F. occidentalis, but did not in F. intonsa especially under short periods. Tomato spotted wilt virus, which is transmitted by these two species, was detected in the weeds infested by the thrips during the winter season. These results suggest that F. occidentalis develops on weeds in the greenhouses while F. intonsa undergoes a diapause in the soil during winter.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.688-696
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• 1999

Changes in quality during frozen storage of meat with thermal equalized freezing and various freezing methods were investigated. When beef were frozen at freezing rate of $0.39{\sim}0.66\;cm/h$, average diameter of ice crystal were about $30{\sim}50\;{\mu}m$ and showed broken tissues or irregular cracks. At freezing velocity of $1.14{\sim}2.26\;cm/h$, ice crystals of about $10{\sim}30\;{\mu}m$ was formed mainly inside or between fiber and slight destruction of tissues was occurred. The average diameter (D) of the ice crystals were related to the characteristic freezing time $(t_c)$ by the equation: $D({\mu}m)=4.089+26.88logt_c\;(r^2=0.913)$. Beef with still-air freezing showed higher drip loss than methods of immersion and thermal equalized freezing. Also, drip loss of pork was relatively lower than beef and showed highest value to 7.39% during storage on 40 days at air-blast freezing method. No apparent change of pH during storage of frozen beef and pork by freezing methods were detected. However, least changes for sample with thermal equalized freezing was found compare to sample with still-air and air blast freezing in VBN and TBA value. The fluctuation of frozen storage temperature did not cause noticeable changes on pH and water content. However, drip loss, VBN and TBA values were increased slowly as frequency of fluctuation increased.

• Food Science and Preservation
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• v.10 no.2
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• pp.125-130
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• 2003

This study was carried out to investigate the thermo-physical properties and design Freezing time prediction model from data of freezing test of Kimchi. Density of Kimchi were measured as 1001.9 ${\pm}$0.03 kg/㎥ at unfrozen state, 987.0 ${\pm}$0.07 kg/㎥ at frozen state and volume of the Kimchi expanded 4.67% at -l5$^{\circ}C$. Initial freezing point of Kimchi and seasoning were -4.0$^{\circ}C$ and -2.5$^{\circ}C$, respectively. Freezing ratio of Kimchi were estimated more than 50％ at -5.0$^{\circ}C$, more than 75% at -l0$^{\circ}C$ and approximately 90% at -25$^{\circ}C$. To obtain equation for freezing time prediction of Kimchi, freezing time(Y) was regressed against the reciprocal( $X_3$) of difference of initial freezing point and freezing medium temperature, reciprocal( $X_4$) of surface heat transfer coefficient, the initial temperature( $X_1$) and thickness( $X_2$) of samples. As results of the multiple regression analysis, equations were obtained as follows. Y$_{kimchi}$=3.856 $X_1$+13982.8 $X_2$+8305.166 $X_3$+ 3559.181 $X_4$-639.189( $R^2$=0.9632). These equations shown better results than previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.827-833
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• 1988

The objectives of this investigation were to develop an improved analytical method and to review with respect to experimental parameters and thermo-physical properties influencing the freezing time prediction. The results indicate that the relationship between freezing time and product size is dependent on the surface heat transfer coefficient. As the magnitude of surface heat transfer coefficient decreases, the influence of product size on freezing time becomes more profound. But the freezing time does decrease slightly as the coefficients are increased to values greater than 150 $w/m^2^{\circ}C$. In addition, influence of thermo-physical properties on the freezing time prediction shown generally density, water content, specific heat and thermal conductivity, in order of % difference. Multiple linear regression equation for freezing time prediction were obtained with respect to 4 different food materials with varying thickness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.207-212
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• 1992

To analyze the freezing phenomena of foodstuffs, the numerical freezing model with 3 steps was established. When water and 2% agar gel were used as samples, Neumann's solution was well matched with experimental results by the numerical model. However, in the case of 20% gelatin gel and pork meat, Weiner's solution was better than Neumann's solution. This numerical freezing model was proved to be good model to describe the freezing phenomena with phase change in the point of versatility and precision.

• Journal of Life Science
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• v.9 no.1
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• pp.44-49
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• 1999

A study was conducted to investigate the possibility of processing seasoned and semi-dried right-eyed flounder (Pseudopleuronects herzensteini) and to examine its quality during storage at $\pm$$3^{\circ}C$ by analyzing the factors such as moisture content, pH, volatile basic nitrogen (VBN), viable cell count and peroxide value (POV). For processing of the seasoned and semi-dried product, optimum conditions of drying temperature and drying time were $20^{\circ}C$ and 4 hrs, respectively, under 50$\pm$5$\%$ of relative humidity and 2 m/sec of air blast speed. The shelf-lives of the products by vacuum-packaging method in nylon/polyethylene/linear low density polyethylene (0.015/0.045/0.040 mm) laminated film bag were 35 and 16 days during storage at $-3^{\circ}C$ and $3^{\circ}C$, respectively.

• Korean Journal of Food Science and Technology
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• v.29 no.5
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• pp.925-931
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• 1997

An attempt was made in this study to investigate the possibility of processing seasoned and semi-dried horse mackerel (Tracharus japonnicus) and to examine its keeping quality, by analyzing the factors such as water content, pH, volatile basic nitrogen, viable cell count, peroxide value, color value and sensory evaluation. For processing of the seasoned and semi-dried product, optimum conditions of drying temperature and drying time were $20^{\circ}C$ and 4 hr, respectively, under $50{\pm}5%$ of relative humidity and 2 m/sec of air blast speed. The shelf-life of the products, vacuum-packaging method in nylon/polyethylene/linear low density polyethylene $(0.015/0.045/0.04\;{\mu}m)$ film bag, was 42 days during storage at $-3{\pm}0.5^{\circ}C$, while that of unpackaged one was only 28 days.