• Food Science and Preservation
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• v.23 no.3
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• pp.438-444
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• 2016

This study was performed to determine the optimal freezing point for the reliable cold storage of Korean agricultural products, and to provide basic data for determining the storage temperature based on the quality characteristics. Additional supercooling temperature analysis was conducted to explore the possibility of supercooling storage. To determine the effects of quality characteristics on the freezing point, the hardness, acidity, moisture and sugar content were analyzed. The crops were frozen using customized cooling unit and their freezing and supercooling points were determined based on their heat release points. The freezing temperatures of garlic, leek, cucumber, hot pepper, grape, oriental melon, netted melon, peach, cherry tomato, plum, daikon, sweet persimmon, apple, sweet potato, mandarin, pear, and strawberry were -1.6, -0.5, -0.5, -0.7, -1.6, -1.6, -1.3, -0.8, -0.3, -1.1, -0.3, -1.7, -1.5, -1.5, -0.8, -1.5, and -$0.9^{\circ}C$, respectively; otherwise, supercooling points were -7.8, -3.7, -3.3, -4.9, -5.7, -4.6, -2.8, -3.3, -5.9, -4.2, -0.8, -4.7, -3.2, -3.7, -4.7, -4.2, and -$3.4^{\circ}C$, respectively. These results suggest that the ideal freezing temperature of crops could be estimated through freezing point depression because of their sugar content, and this technique should be used to maintain an optimum storage temperature. However, cold storage is complicated and further study is required because of the effects of long-term cold storage on the crops.

• Food Science and Preservation
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• v.15 no.5
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• pp.675-681
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• 2008

This study investigatedthe quality of mashed red pepper after application of various freezing and thawing conditions. Two freezing temperatures ($-70^{\circ}C$, $-10^{\circ}C$), two thawing temperatures ($0^{\circ}C$, $40^{\circ}C$), and two thawing methods (water-thawing, air-thawing), were employed. Changes in levels of capsaicinoids, vitamin C, free sugars, organic acids, and capsanthin were measured. Capsaicinoids, vitamin C,and free sugar contents were lowest in pepper treated at $-10^{\circ}C/40^{\circ}C$ (freezing/thawing), and the loss rates were 38.0, 79.4 and 24.6%, respectively. When thawing methods were compared, chemical contents were higher in air-thawed samples than in water-thawed peppers, but there was a statistically significant difference only in vitamin C content. Free sugar content after $-70^{\circ}C$ freezing were higher than after $-10^{\circ}C$ freezing, irrespective of the thawing method used. Initial citric acid, malic acid, and succinic acid contents were 44.90, 30.76 and 20.65 mg/100 g, and there was no significant difference between peppers treated with different freezing and thawing conditions. It is recommended that the best method for preserving the overall quality of mashed red pepper is freezing at $-70^{\circ}C$ and thawing at $0^{\circ}C$ in air.

• Food Science and Preservation
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• v.14 no.3
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• pp.227-232
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• 2007

The development of an effective long-term storage protocol for harvested fresh pepper is urgently required to increase the market for pepper products. The protocol must minimize quality loss, so that the product may be used either as a spice or as a raw material for processed pepper products, both in the home and in food processing plants. We investigated the optimum size of pepper fruits, freezing temperatures, storage periods, and thawing methods, to establish an optimum storage protocol. This study was conducted not only to develop freezing and thawing methods for long term storage of harvested red pepper, but also to develop processed pepper products utilizing the stored pepper. We aimed to expand the pepper products market and to increase the incomes of pepper growers. Whole red pepper, sliced red pepper, and crushed red pepper were frozen and stored at $-5^{\circ}C,\;-20^{\circ}C,\;or\;-40^{\circ}C$. The soluble solid content and the vitamin C level showed maximal stability at $-40^{\circ}C$, although total free sugars decreased on storage at all temperatures tested. Such Changes were more marked at $-5^{\circ}C$ than at the other(lower) temperature tested. The vitamin C content of whole red pepper was higher than that of sliced red pepper or crushed red pepper. Room-temperature thawing resulted in twice the drip loss seen on low temperature($5^{\circ}C$) thawing or microwave oven thawing. Brown discoloration was a serious problem with room temperature thawing. Total free sugars were higher in samples thawed at low temperature or in the microwave oven, compared to the level seen after room-temperature thawing. pepper samples thawed at low temperature scored higher in sensory tests than samples thawed at room temperature.

• Applied Microscopy
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• v.42 no.2
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• pp.111-114
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• 2012

The scanning electron microscopy is an ideal technique for examining plant surface at high resolution. Most hydrate samples, however, must be fix and dehydrate for observation in the scanning electron microscope. Because the microscopes operate under high vacuum, most specimens, especially biological samples, cannot withstand water removal by the vacuum system without morphological distortion. Cryo-techniques can observe in their original morphology and structure without various artifacts from conventional sample preparation. Rapid cooling is the method of choice for preparing plant samples for scanning electron microscopy in a defined physiological state. As one of cryo-technique, high-pressure freezing allows for fixation of native non-pretreated samples up to $200{\mu}M$ thick and 2 mm wide with minimal or no ice crystal damage for the freezing procedure. In this study, we could design to optimize structural preservation and imaging by comparing cryo-SEM and convention SEM preparation, and observe a fine, well preserved Arabidopsis stem's inner ultrastructure using HPF and cryo-SEM. These results would suggest a useful method of cryo-preparation and cryo-SEM for plant tissues, especially intratubule and vacuole rich structure.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.4
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• pp.267-291
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• 2010

Life can be kept in suspended animation either before fertilization at oocyte stage or after fertilization at different stages of embryonic development for a variety of reasons. It not only has potential applications in fertility preservation and management in human but also has important roles in the preservation and management of animal genetic resources, low-cost international movement of selected genetics, and rapid dissemination of germplasm through assisted reproductive technologies (ART) and genetic engineering. Currently, slow-freezing and vitrification are the two approaches by which oocytes and embryos can be cryopreserved for long-term storage. Both of these methods have their own advantages and disadvantages but allow the cryopreservation of oocytes and embryos with comparable efficiency. Vitrification of oocyte and embryos, although proven successful just 13 years after slow-freezing, is generally considered an emerging technology and appears to slow gain acceptance in both animal and human ART despite having controversial storage and contamination issues. In this manuscript, we discuss the basic techniques of oocyt/embryo cryopreservation and review the current status and recent developments in vitrification.

• Journal of Food Hygiene and Safety
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• v.24 no.3
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• pp.217-225
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• 2009

The study was conducted to evaluate the effect of drying, curing and freezing on the quality of beef. Three types of dried (without salt = $T_1$, with salt = $T_2$ and salt + spices = $T_3$); three types of cured (salt curing = $T_4$, sugar curing = $T_5$ and brine curing = $T_6$) and three types of frozen beef ($0^{\circ}C=T_7^{\circ}C$, $-10^{\circ}C=T_8$ and $-20^{\circ}C=T_9$) were analyzed at different time intervals up to the period of 180 d. Parameters studied were protein, fat, ash, color and cooking loss of beef. All the chemical constituents (protein, fat and ash) were decreased gradually up to 120 d. The decreasing trend was observed rapid after 120 d up to 180 d of preservation. Highest protein loss was found in $T_7$ (11.1 %) and the lowest protein loss was found in $T_6$ (3.85%) in 180 d preservation and significant (p < 0.01) differences were observed among the different preservation methods. Highest fat loss was observed in $T_6$ (7.62%) and the lowest fat loss was observed in $T_2$ (3.18%) and the differences were also significant (p < 0.05) among different methods during the experimental period. Spices dried beef showed a brighter color than others and cured beef showed brown color and the intensity of color was reduced gradually with the increasing of storage period. $T_9$ showed the lowest cooking loss among 3 treatments of frozen beef and the differences also significant (p < 0.01) up to 180 d. It might be stated that sugar curing ($T_5$) and spices drying ($T_3$) would be the useful technique of meat preservation in rural areas and freezing ($T_9$) would be used in large scale preservation at urban areas.

• Korean Journal of Poultry Science
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• v.41 no.4
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• pp.261-270
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• 2014

This study was conducted to establish the method for preserving chicken primordial germ cells (PGCs) that enables long-term storage in liquid nitrogen ($LN_2$) for developmental engineering or preservation of species. The purpose of this study is to clarify the effects of simple freeze-thaw treatment on viability of PGCs in chickens and to the optimal protocol for PGCs freezing. PGCs obtained from the germinal gonade of an early embryos of 5.5~6 day (stage 28) of Isa Brown, Korean Ogye (KO), White Leghorn and Commercial breeds, using the MACS method were suspended in a freezing medium containing a freezing and protecting agents (e.g. dimethyl sulfoxide (DMSO), ethylene glycol (EG) and propylene glycol (PG)). The gonadal cells, including PGCs, were then frozen in 1 of the following cryoprotectant treatments : 2.5%, 5%, 10%, 15%, and 0% cryoprotectant (DMSO, EG, PG) as a control. Effects of exposure to simple freezing, with different concentrations of the cryoprotectant solution, were examined. After simple freezing, the viability of PGCs after freeze-thawing was significantly higher for Commercial breeds ($88.7{\pm}2.4%$) than KO ($85.1{\pm}0.4%$), Isa Brown ($84.6{\pm}0.2%$) and White Leghorn ($85.9{\pm}0.1%$) (p<0.05) using 10% EG cryoprotectant. Therefore, these systems may contribute in the improvement of cryopreservation for a scarce species in birds preservation. This study established a method for preserving chicken PGCs that enables systematic storage and labeling of cryopreserved PGCs in liquid ($LN_2$) at a germplasm repository and ease of entry into a database.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.1
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• pp.16-18
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• 2002

During the process of freezing, spermatozoa suffer cold shock which increases their susceptibility to lipid peroxidation which plays an important role in ageing of spermatozoa, shortening their life span and affecting the preservation of semen. An experiment was therefore conducted to study the effect of addition of natural antioxidants into semen diluents on the preservability of buffalo semen. Split semen samples were extended in milk egg yolk diluents fortified with vitamin E (MYE), vitamin C (MYC) and control group (MYO); Tris-egg yolk diluents fortified with vitamin E (TYE), vitamin C (TYC) and control group (TYO) and evaluated for their preservabilities at 4-7$^{\circ}C$ and $37^{\circ}C$. Overall least squares mean of percent motility observed after 0, 24, 48, 72 and 96 h of preservation at 4-7$^{\circ}C$ were 66.70, 54.00, 36.80, 21.90 and 12.50, respectively while the estimates for semen extended in MYE, MYC, MYO, TYE, TYC and TYO were 44.80, 42.70, 38.70, 36.00, 35.20 and 33.00 percent, respectively. The results showed that motility was significantly (p<0.01) affected by extender (extender-antioxidant combination) and preservation interval. Overall least squares mean percent motility observed after 0, 4, 8, 12 and 24 h of preservation at $37^{\circ}C$ were 68.50, 58.90, 45.00, 38.10 and 18.10 percent, respectively, while the estimates for semen extended in MYE, MYC, MYO, TYE, TYC and TYO were 48.20, 49.30, 46.80, 45.30, 42.30 and 42.50 percent, respectively. Extender and storage interval were found to be significantly (p<0.01) affecting spermatozoa motility on room temperature preservation. The results indicated that the incorporation of antioxidants, especially vitamin E, had beneficial effect on preservability of buffalo semen.

• Journal of Korean Society of Forest Science
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• v.98 no.1
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• pp.115-124
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• 2009

New strain needs to maintain desirable characteristics for long term when it was bred, but in lapse of time it degenerates into a bad condition. Therefore the influence of temperature on the viability and survival rates of Lentinula edodes strains were examined after cryopreservation. Also, liquid nitrogen preservation for L. edodes has been proved to be one of the most reliable method. However, a mechanical damage of strain is inevitable during cryopreservation of the fungus because the fungus is very sensitive to stress of cooling rate in the freezing process. So we tried to find out state change of L. edodes with a programmable freezer. L. edodes strains were preserved at $-20^{\circ}C$, $-80^{\circ}C$ and $-196^{\circ}C$ for 50 days. At $-20^{\circ}C$, its mycelial growth became extinct. When thawed, the growth of mycelia which were preserved at $-80^{\circ}C$ was fastest. Attempts were made to investigate viability of L. edodes strains after freezing at $-80^{\circ}C$ and $-196^{\circ}C$, respectively. As the result, more than 90% showed high survival rate of strains tested at $-80^{\circ}C$ and $-196^{\circ}C$. Mycelial growth between apical and basal parts of colony after freezing preservation for 50 days was compared. At apical and basal parts, the survival rates showed 100% at $-80^{\circ}C$, but 98% and 94% at $-196^{\circ}C$, respectively. We confirmed that the ice crystal formation temperatures of L. edodes strains were $-6.0^{\circ}C$ for Sanlim 1, $-5.5^{\circ}C$ for the Sanlim 2, $-4.0^{\circ}C$ for the Sanlim 3 and $-15.5^{\circ}C$ for the Sanzo 302. These results indicated that L. edodes strains showed completely different responses to the ice crystal formation. We knew the fact that even the same species, especially L. edodes, they displayed completely different responses to the same freezing condition. Also, this has nothing to do with the connection between temperature type and freezing point. And a protocol was tried to minimize state change of L. edodes strains using programmable freezer when they are frozen, but it was not effective on them.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.57-60
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• 2008

This study investigated the results of insulation heat curing method using double layer bubble sheet in slab concrete and mass concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 6 and 15℃ even in case outside temperature drops -9℃ below zero until the 2nd day from piling, and in the case of mass concrete, with the maximum temperature difference between the center and surface less than 4℃, crack occurrence index was close to 2 and no hydration heat crack occurred by internal constraint. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.