• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.267-272
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• 1996

Effect of freezing of soybeans on instrumental and sensory textures of soybean curd was investigated. The hardness, gumminess and chewiness of soybean curd prepared with frozen soybeans were about three times as high as those prepared with unfrozen soybeans, while cohesiveness and elasticity were affected little by freezing. Sensory evaluation showed that freezing improved the quality of soybean curd. Instrumental and sensory textures of soybean curd prepared with frozen soybeans were excellent and almost same regardless of the boiling time when the soy slurry was boiled for 2.5 min or 5 min. However, the textures of soybean curd prepared with unfrozen soybeans were deteriorated by reducing the boiling time to 2.5 min. It was postulated that freezing facilitate the heat-denaturation of soyprotein to enhance aggregation of soy proteins and formation of cross-linkage between aggregate and $Ca^{++}$. Frozen soybeans resulted in soybean curd which lower fat content, while protein content of soybean curd was almost he same. Frozen soybeans gave a lower yield of soybean curd, which is supposed to be caused by the more fat loss during whey-off.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.261-272
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• 2009

An experimental study of the accelerated weathering was performed to investigate the variations of physicomechanical properties of deteriorated rocks due to freeze-thaw weathering for the Jurassic granite specimens from Wonju, Gangwon-do. Each complete cycle of freeze and thaw was lasted 24 hours, comprising 2 hours saturating in vacuum chamber, 8 hours freezing at -20$\pm1^{\circ}C$ and 14 hours thawing at room temperature. Freeze-thaw cycles were implemented with measuring the index physical properties as well as geometries of microfractures. The seismic velocity was found to decrease with increasing freeze-thaw cycles. On the other hand, absorption tends to increase with freeze-thaw cycles. In the end, it was concluded that variations of the index properties of deteriorated specimen depend on its initial properties and flaws in rock. The size and density of the traces of the microfracture on slab specimen were changed continuously with increasing freeze-thaw weathering. The results obtained in this study show that the box fractal dimension($D_B$) has the strong capability of quantifying the combined effect of size and density of the microfractures.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.146-157
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• 2009

An experimental study of accelerated weathering on mudstone sample specimens from Haman, Gyeongnam was performed to investigate the variations of physico-mechanical properties of deteriorated rocks due to freeze-thaw weathering. Each complete cycle of freeze and thaw lasted 24 hours, comprising 2 hours of saturating in vacuum chamber, 8 hours of freezing at $-16{\pm}1^{\circ}C$ and 14 hours of thawing at room temperature. Total of 55 cycles of freeze-thaw were completed with measuring the index properties as well as geometries of microfractures. The measured specific gravity and P-wave velocity found to decrease with increasing freeze-thaw cycles. On the other hand, absorption ratio and effective porosity were continuously increased with increasing freeze-thaw cycles. It was found that the index properties of deteriorated sample specimen depend on its initial properties and flaws in rock. The size and density of the traces of the microfracture on slab specimen exhibited abrupt changes after 30 cycles of freeze-thaw weathering. The results obtained in this study show that the box fractal dimension($D_B$) given in this paper has the strong capability of quantifying the size and density of the microfracture.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.587-593
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• 2019

This study were subjected to accelerated weathering test under freeze-thaw and pressure conditions to observe initiation and propagation of cracks using CLSM. Applied stress was set at 50 MPa, 55 MPa, 70 MPa for 3 samples each by using compressor and freeze-thaw experiment was conducted while samples maintained that condition. In freeze-thaw experiments, a temperature range was set to -20~40℃ which was 1 cycle for 6 hours. The freeze-thaw cycle was composed of time which reached to set temperature for 1 hour and holding time for 2 hours. On the basis of this cycle, surface of samples was observed by CLSM after each 20 freeze-thaw cycle. From this research, according to increase freeze-thaw cycle, there were 7, 10, 19 each cracks and High pressured sample's accumulate length was longer than low pressured sample's. High pressured sample's crack velocities were also faster than low pressured sample's which were calculated by accumulate length and freeze-thaw cycle.

• Bulletin of Food Technology
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• v.25 no.2
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• pp.116-128
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• 2012

식품동결에 의한 품질손상에 있어 크게 영향을 미치는 인자 중의 하나가 체적변화에 의한 조직 파괴이므로 식육 및 과채류의 냉동시 내부압력에 따른 조직파괴를 방지하기 위한 기초연구로 다양한 동결방법에 따른 내부압력 변화에 대하여 조사한 결과, 급속 및 완만동결시 우육의 내부압력 변화 경향은 동결 직전에 급격히 상승한 후 동결 초기부터 최대빙결정생성대를 통과하는 동안은 급격히 감소하다가 다시 온도가 내려감에 따라 압력변화는 증가와 감소를 반복하여 상승하는 경향을 보여 주었고, 동결시의 내부압력 크기는 약 8~10 psig 수준이며, 내부압력의 변화 경향은 정지공기식보다 침지식에서 약 1 psig 정도 크게 나타났다. 냉동냉장시에 일어나는 내부압력의 상하변화는 돈육의 품온차가 ${\pm}1^{\circ}C$일 때, 시료중량에 따라 1.84~2.32 psig 정도의 내부압력 차가 반복적으로 발생됨을 알 수 있었다. 또한, 돈육의 해동시 내부압력은 해동 개시 후 급격히 상승하여 5분 이내에 최고압력에 도달한 이후에는 서서히 하강하였으며, 해동시에 발생한 내부압력의 값은 동결시의 내부압력 값보다도 대부분 크게 나타났다. 또한, 균온처리한 우육의 동결시 내부압력 값은 약 1~4 psig 수준으로 균온처리하지 않은 우육에 비하여 매우 적게 나타났으며, 동결소요시간도 약 10~20% 정도 짧게 나타났다. 그리고 균온처리 및 다양한 동결방법에 따른 동결식육의 조직과 냉동냉장 중의 품질변화를 비교 검토한 결과, 동결방법에 따른 드립손실율은 우육의 경우 정지공기식으로 처리한 시료는 타 처리구에 비해 계속 높게 나타났으며, 돈육은 우육에 비해 상대적으로 드립손실량이 적게 나타났으나 송풍식으로 처리한 시료에서 저장 40일째, 7.39%로 가장 높게 나타났다. 동결 우육 및 돈육의 pH변화는 뚜렷한 차이를 나타내지 않았으며, VBN 및 TBA값에 있어서는 균온 처리한 시료가 완만 및 급속동결 처리한 타 시료에 비해 저장 200일까지 가장 변화가 없었다. 동결저장온도의 상하변동에 있어서는 온도변동 횟수가 증가할수록 pH 및 수분함량은 뚜렷한 변화가 없었으나 드립손실율, VBN 및 TBA값은 온도 변동횟수가 증가할수록 서서히 증가하는 경향을 보여 주었다.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.118-118
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• 2003

홍조류 김속 해조 5종(모무늬돌김, 방사무늬김, 참김, 긴잎돌김, 잇바디돌김)의 사상체를 2단계 냉각법으로 액체질소 중에서 동결보존을 시행하였다. 시료를 여러 가지 동해보호제에 현탁시킨 후 프로그램 냉각기로 4시간에 걸쳐 -4$0^{\circ}C$까지 천천히 동결시켰다. 일차 완만동결 종결 후 즉시 동결용 튜브를 액체질소 중에 수용하여 급속동결 시켰다. 해동시에는 4$0^{\circ}C$의 항온수조에서 대부분의 얼음 결정을 급격히 해동시킨 후 냉각수내에서 완전히 해동시켰다. 생존률은 김 속 해조에서는 neutral red로 염색하여 산정하였으며 50% 해수에 10% DMSO와 0.5M sorbitol 혼합액을 동해보호제로 사용하였을 때의 생존율이 54.6~70.9%였다.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.280-280
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• 2004

본 연구는 개 동결정액 희석액에 pentoxyfilline을 첨가하여 융해 후 정액성상에 미치는 영향을 조사하였다. 공시견은 2∼3세의 Beagle, English cockers spania, Collie, Grey hound, Shihtzu 5두를 공시하였다. 정액은 수압법 또는 인공질법으로 채취하였고 채취된 정액은 Rota 등(EYT : Egg-yolk Tris extender, 1995)의 방법에 따라 동결정액을 제조하였다. Pentoxyfilline은 동결 보호제가 들어 있는 2차 희석액에 0 mM, 1 mM, 3 mM 농도로 첨가하였으며, 5℃에서 2시간 glycerol 평형을 한 후에 액체질소에 10분간 예비 동결하여 동결정 액을 제조하였다. (중략)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.463-470
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• 1998

To improve muscle quality and prolong freshness of sashimi, the effects of freezing-thawing condition on physicochemical and rheological properties of plaice muscle were investigated. Muscle tested were frozen with quick freezing (liquid nitrogen gas) or slow freezing ($-15^{\circ}C$ air). Transition time of zone of ice crystal formation was within 10 minute for quick freezing and 110 minute for slow freezing. Time required for thawing to $0^{\circ}C$ in muscle temperature by various thawing methods was shortest with $25^{\circ}C$ tap water, followed by $15^{\circ}C$ tap water, $10^{\circ}C$ tap water, $25^{\circ}C$ air, $5^{\circ}C$ tap water and $0^{\circ}C$ cold water. Breaking strength of muscle was higher in quickly frozen sample than in slowly frozen sample. According to sashimi term, changes in breaking strength of muscle did not show any difference in quickly frozen sample, while showed significant difference in slowly frozen sample. The remaining content of ATP was not effected by freezing speed, and ATP content was apt to higher in quickly thawed sample than in slowly thawed sample. IMP was the majority of ATP and it's related compounds of sample after freezing and thawing. Collagen matrix was weakened markedly in slowly frozen sample than in quickly frozen sample.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.85-92
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• 1999

This study was designed to determine effect of cryoprotectant kinds and cell stages on OPP vitrification method in mouse embryos. The freezing speed, cryoprotectants and cell stage could affect of embryo viability following various vitrification methods. The vitrification solution used were consisting of 40% (v/v) ethylene glycol, 18% (w/v) Ficoll, 0.3 M sucrose solution in holding medium (D-PBS supplemented with 5% FCS: HM) (EFS) or 16.5% ethylene glycol , 16.5% dimethyl sulfoxide, 0.5 M sucrose in HM (EDS). The embryos were collected from oviduct at 18 h after hCG injection and then washed and cultured in mHTF medium until use. In experiment 1, the blastocysts were vitrified by OPP straw to determine the optimal vitrification solution of EFS or EDS. The post-thaw survival rates at re-expanded stage rates were significantly different between EFS and EDS (95.0 vs 100%), but at hatching stage was not different between EFS and EDS (90.0 vs 95.0%). respectively. In experiment 2, zygotes, 2-, 4-cell, morula and blastocysts were vitrified by OPP method to determine the acceptable of early stage embryos. The development rates to expanded blastocyst in zygote (70.0%) were significantly lower rather than those in 2-, 4- 8-cell, compacted morula or blastocyst (89.7, 90.0, 92.8, 97.6 or 97.5%), respectively. However, the cell number of post-thaw developed to expanded blastocyst in blastocyst and control blastocyst stage (39.6$\pm$2.81, 35.7$\pm$2.98) were significanty higher than those in zygote, 2-, 4-, 8-cell, compacted morula (29.8$\pm$3.21, 31.3$\pm$3.83, 29.3$\pm$3.58, 28.9$\pm$3.21 or 30.8$\pm$2.93). In experiment 3, the zygotes were exposed in VSl for 1, 2, and 3 min to the optimal exposed time. The cleavage rates (91.6, 88.5, 88.9%) and develop mental rates to blastocyst (83.3, 74.3 and 69.4%) depends on the exposed time in VSl were not significantly different among 1, 2, or 3 min, respectively. The cell number also were not significantly different among exposed time in VS1. respectively. These results indicate that OPP method could be useful for vitrification either EFS or EDS vitrification solution. The post-thaw survival rates at zygote were significantly lower than those at 2-, 4-, 8-cell, morula or blastocyst, respectively. The zygote stage were more sensitive rather than late stage embryos. The exposing time in VS1 for 1 min was better than that for 2 or 3 min, even it was not significantly different. The OPP vitrification method could be useful of mouse embryos either with EFS or EDS vitrification solution.

• 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.