• Title/Summary/Keyword: freezing

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A Study on the Deterioration Prediction Method of Concrete Structures Subjected to Cyclic Freezing and Thawing (동결융해 작용을 받는 콘크리트 구조물의 내구성능 저하 예측 방법에 관한 연구)

  • Koh, Kyung-Taeg;Kim, Do-Gyeum;Cho, Myung-Sung;Son, Young-Chul
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.5 no.1
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    • pp.131-140
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    • 2001
  • In general, the deterioration induced by the freezing and thawing cyclic in concrete structures often leads to the reduction in concrete durability by the cracking or surface spalling. If it can prediction of concrete deterioration subjected to cyclic freezing and thawing, we can rationally do the design of mix proportion in view of concrete durability and the maintenance management of concrete structures. Therefore in this study a prediction method of deterioration for concrete structures subjected to the irregular freezing and thawing is proposed from the results of accelerated laboratory freezing and thawing test using the constant temperature condition and the in-situ weathering data. Furthermore, to accurately predict the concrete deterioration, a method of modification for the effect of hydration increasing during rapid freezing and thawing test is investigated.

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An Experimental Study on Sea Water Freezing Behavior Along Horizontal Cooled Cylinder With Bubbly Flow (기포를 동반한 유동장에서의 냉각원과 주위의 해수동결에 관한 실험적 연구)

  • Park, D.S.;Yoon, S.H.;Kim, M.H.;Lee, Y.H.;Oh, C.
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.4
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    • pp.825-832
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    • 2001
  • This study was experimentally performed to investigate freezing behavior of sea water along horizontal cooled a circular tube with bubbly flow. The experiments were carried out for a variety of parameter, such as sea water velocity, air-bubble flow rate, and cooled-tube temperature. The shape of freezing layer, freezing rate and salinity of frozen layer were observed and measured. And the flow patterns around cooled tube were visualized using the PIV to analyze the relationship between the flow structure and the freezing characteristics. It was found that the experimental parameters gave a great influence on the freezing rate and the salinity of the frozen layer.

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the Effect of Freezing and Thawing Rates on the Percentage of Sub-lethally Injured Total Coliform on Beef Surface (냉동 및 해동속도가 우육표면 대장균군의 반치사적 손상율에 미치는 영향)

  • 이용욱;황성우
    • Journal of Food Hygiene and Safety
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    • v.3 no.1
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    • pp.19-26
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    • 1988
  • Most of meat spoilage bacteria area Gram negative, which are very sensitive to freezing ; for instance , 90% of E. coli cells are killed or sub-lethally injured by freezing at -3$0^{\circ}C$, and the freeze-injury rate is dependent upon freezing rate. Since the injured bacterial cells are sensitive to selective agents, they fail to multiply in selective media. Injured bacterial cells are, however, capable of spontaneous repair at appropriate environmental and nutritional conditions . Enumeration of injured bacterial cells involves artificial induction of repair at these conditions. Cubic beef samples(3$\times$3$\times$3cm) were frozen at -6$0^{\circ}C$, -4$0^{\circ}C$, or -18$^{\circ}C$. The samples frozen at each temperature were thawed at 4$^{\circ}C$, 2$0^{\circ}C$, or by microwave . After these respective freezing an thawing treatments, the percentage of sub-lethally injured total coliforms out of total surviving ones was measured and compared. The results were as follows: 1. The interaction between freezing and thawing on injury rate was not significant. 2. The injury rates(as means of all three thawing treatments post-freezing) by freezing at -6$0^{\circ}C$, -4$0^{\circ}C$, or -18$^{\circ}C$ were 32.2$^{\circ}C$ and 19.2$^{\circ}C$ respectively . 3. The injury rates(as means of all three freezing treatments)by thawing at 4$^{\circ}C$, 2$0^{\circ}C$, or by microwave were 49.3%, 11.7% and 21.0% respectively. The highest injury rate was caused by freezing at -6$0^{\circ}C$ and subsequent thawing at 4$^{\circ}C$. However since the injury rates by freezing treatment were not significantly different, freezing at -18$^{\circ}C$ and subsequent thawing at 4$^{\circ}C$ can also be recommended , from an economic perspective.

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Changes in Ultrastructure and Sensory Characteristics on Electro-magnetic and Air Blast Freezing of Beef during Frozen Storage

  • Choi, Yun-Sang;Ku, Su-Kyung;Jeong, Ji-Yun;Jeon, Ki-Hong;Kim, Young-Boong
    • Food Science of Animal Resources
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    • v.35 no.1
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    • pp.27-34
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    • 2015
  • The ultrastructure in the beef muscle of the electro-magnetic resonance and air blast freezing during the frozen storage, and the changes in the quality characteristics after thawing were evaluated. The size of ice crystal was small and evenly formed in the initial freezing period, and it showed that the size was increased as the storage period was elapsed (p<0.05). The beef stored by the electro-magnetic resonance freezing showed the size of ice crystal with a lower rate of increase than the air blast freezing during the frozen storage. The thawing loss of beef stored by the electro-magnetic resonance freezing was significantly lower than the air blast freezing during frozen storage (p<0.05), and it showed that the thawing loss of the round was higher than the loin. Water holding capacity decreased as the storage period became longer while the electro-magnetic resonance freezing was higher than the air blast on 8 month (p<0.05). As a result of sensory evaluation, the beef stored by the electro-magnetic resonance freezing did not show the difference until 4 months, and it showed higher acceptability in comparison with the beef stored by the air blast freezing. Thus, it is considered that the freezing method has an effect on the change in the ultrastructure and quality characteristics of the beef.

Comparison of osteoinductive efficacy of freezing, freeze-drying and defat-freezing implant preparation for allograft in rabbit (토끼 동종골이식에서 이식골편의 동결법, 동결건조법, 탈지 후 동결법 처리에 따른 신생골 형성능력 비교)

  • Lee, Jong-Il;Song, Ha-Na;Kim, Nam-soo;Choi, In-hyuk
    • Korean Journal of Veterinary Research
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    • v.47 no.2
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    • pp.219-228
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    • 2007
  • Bone allograft had been increased the need because autogenous bone graft is associated with donor site morbidity and is restricted in quantity. The bone allograft implants have to prepare properly for increasing osteoinductive ability and decreasing immune responses before providing to graft. The purpose of this study was to investigate the efficacy on new bone formation in bone allografts by treatment of implants. Cortical bone allografts were transplanted to experimental defects on midshaft of diaphyseal fibulae in 15 rabbits, which were divided to 3 experimental groups according to the preparation methods-freezing, freeze-drying, defat-freezing. The grafted regions of fibulae of all groups had been radiographed biweekly for 16 weeks to observe new bone formation and union between implant and recipient bone. Bone Alkaline Phosphatase (BALP) in all groups was evaluated biweekly till the end of the experiment to determine osteoblast activities. Unions between implant and recipient bone were observed at 30% (3 of 10 cases) of freezing, 50% (5 of 10 cases) of freeze-drying and 80% (8 of 10 cases) of defat-freezing. BALP was increased over 100% from before graft at 2 weeks of graft procedures in all union cases of freezing and defat-freezing group, then gradually decreased till 16th week. In non-union cases, there is no significant variation in BALP value. Defat-freezing method for allograft implants might be more effective for osteoinductive efficacy of implants than freezing and freeze-drying method.

Comparison of the Efficiency between Slow Freezing and Vitrification Method for Cryopreservation of Human Embryos (인간 수정란의 완만 동결과 유리화 동결의 비교)

  • Kim, Eun-Kuk;Kim, Mi-Yeon;Son, Sun-Mi;Kim, Dong-Won
    • Journal of Embryo Transfer
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    • v.23 no.1
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    • pp.19-24
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    • 2008
  • The purpose of this study was to compare the efficiency of slow freezing with that of vitrification method for the cryopreservation of human embryos. Human embryos were derived from in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and the mixed solution of propanedial (1.5, 1.0, 0.5M PROH) and sucrose (0.1M), ethylene glycol (7.5, 15%), dimethyl sulfoxide (7.5, 15% DMSO), sucrose (0.5, 1.0M) and SPS (Serum Protein Substitute) was used for a cryoprotectant for slow freezing and vitrification solution, respectively. Rates of recovery after thawing, morphological normality, post-thaw viability, arrest, morphological abnormality and preimplantation development were compared between two protocols. After freezing-thawing, recovery and survial rate of slow freezing was (88.6% and 73.4%), whereas vitrification was (99.2% and 96.2%) (p<0.05). The arrest rate of slow freezing was significantly lower compared with those of vitrification(8.7% vs 29.9%) (p<0.05). Preimplantation development to the 2-cell (83.8% vs 67.7%), 4-cell (69.0% vs 47.2%) and 8-cell (62.4% vs 37.8%) stages 24, 48 and 72 h after thawing, respectively, were higher in the slow freezing than the vitrification. After slow freezing and vitrification of human embryo at 2-8cell stage, the rate of recovery rate, survival rate and partial damage rate were 92.0% vs 100%, 80.4% vs 96.2% and 52.2% vs 19.0%, respectively. And partial damage rate was significantly lower than those of slow freezing method (p<0.05). These results demonstrate that a slow freezing using PROH is more efficient than a vitrification for cryopreserving the human zygotes, although the vitrification yielded better recovery, survival and partial damage of frozen-thawed 2-8 cell stage embryos than slow freezing method.

Changes in Quality of Welsh Onion (Allium fistulosum L.) during the Freezing Storage Period under Different Freezing Conditions (냉동조건에 따른 대파의 냉동저장 중 품질변화)

  • Kim, Seok-Young;Kim, Hee-Sun;Kim, Jin-Se;Han, Gwi-Jung
    • Korean journal of food and cookery science
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    • v.32 no.6
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    • pp.665-676
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    • 2016
  • Purpose: This study was conducted to find the optimal freezing method and storage conditions for welsh onion. Methods: Cut welsh onions (0.3 cm) were packed in nylon/linear low density polyethylene (LLDPE) film bags, and frozen utilizing still-air freezing at -$20^{\circ}C$ (SAF20) and -$40^{\circ}C$ (SAF40), and immersed-liquid freezing at -$40^{\circ}C$ (ILF40); they were then stored at -$20^{\circ}C$ for 7 months. During storage, quality characteristics were measured monthly. Results: Drip loss was the lowest in the ILF40 packaging. Color difference in the stem (white part) did not differ significantly according to freezing conditions and storage time. Color difference in the leaf (green part) and stem was the lowest in SAF20. pH remained unchanged, while total aerobic bacterial count, pyruvic acid and moisture content decreased during storage. Pyruvic acid content of ILF40 was the highest among the freezing treatments. Fructose and glucose contents increased gradually during storage. Citric acid, malic acid, succinic acid and fumaric acid contents were unaffected, regardless of the freezing conditions. Conclusion: The optimal freezing method for welsh onions with the least quality changes was determined to be immersed liquid freezing, following by preservation up to 7 months by freeze-storing.

Effects of Electromagnetic Heating on Quick Freezing

  • Kim, Jinse;Park, Jong Woo;Park, Seokho;Choi, Dong Soo;Choi, Seung Ryul;Kim, Yong Hoon;Lee, Soo Jang;Yoo, Seon Mi;Han, Gui Jeung
    • Journal of Biosystems Engineering
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    • v.40 no.3
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    • pp.271-276
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    • 2015
  • Purpose: Quick freezing is widely used in commercial food storage. Well-known freezing techniques such as individual quick freezing require a low-temperature coolant and small cuts for the heat-transfer efficiency. However, the freezing method for bulk food resembles techniques used in the 1970s. In this study, electromagnetic (EM) heating was applied to improve the quick freezing of bulk food. Methods: During freezing, the surface of food can be rapidly cooled by an outside coolant, but the inner parts of the food cool slowly owing to the latent heat from the phase change. EM waves can directly heat the inner parts of food to prevent it from freezing until the outer parts finish their phase change and are cooled rapidly. The center temperature of garlic cloves was probed with optical thermo sensors while liquid nitrogen (LN) was sprayed. Results: When EM heating was applied, the center cooling time of the garlic cloves from freezing until $-10^{\circ}C$ was 48 s, which was approximately half the value of 85 s obtained without EM heating. For the white radish cubes, the center cooling time was also improved, from 288 to 132 s. The samples frozen by LN spray with EM heating had a closer hardness to the unfrozen samples than the samples frozen by LN only. Conclusions: The EM heating during quick freezing functions to maintain the hardness of fresh food by reducing the freezing time from 0 to $-10^{\circ}C$.

A Study on the Changes of Pork Quality by Freezing and Thawing Methods (돈육의 냉해동 조건에 따른 품질 변화에 관한 연구)

  • Kang, Byung-Sun;Kim, Dong-Ho;Lee, Oh-Seuk
    • Culinary science and hospitality research
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    • v.14 no.2
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    • pp.286-292
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    • 2008
  • The purpose of this study was to examine the effects of freezing and thawing methods on the quality of pork meat. The freezing methods for pork meat were the cryogenic freezing with liquid nitrogen gas, fast freezing at $-70^{\circ}C$ and normal freezing at $-20^{\circ}C$. The thawing methods were tested on low temperature thawing at refrigerative temperature($4^{\circ}C$), room temperature($20^{\circ}C$), high temperature($60^{\circ}C$) and using microwave. The quality of pork meat frozen by cryogenic methods was better than those of fast and normal freezing methods. The cooking hardness of pork meat frozen by cryogenic method showed the highest value as 1,898 g. In case of fast freezing, the hardness of pork meat was 1,472 g and that of normal frozen pork meat was 1,541 g. The high cooking hardness value of cryogenic frozen pork meat showed that the cryogenic freezing method made less freeze damage like textural softness. The drip-loss of pork meat thawed at refrigerative temperature($4^{\circ}C$), room temperature($20^{\circ}C$), high temperature($60^{\circ}C$) were shown lower than that of microwave thawing. The cooking hardness of pork meat that was thawed by microwave showed the lowest value among the thawing methods. The cryogenic freezing was the most useful freezing method for preserving quality, decreasing the freeze damage of pork meat. And thawing at refrigerative temperature was the most effective method to prevent quality loss and weight loss by drip-loss.

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Evaluation of the Activities of Antioxidant Enzyme and Lysosomal Enzymes of the Longissimus dorsi Muscle from Hanwoo (Korean Cattle) in Various Freezing Conditions

  • Kang, Sun Moon;Kang, Geunho;Seong, Pil-Nam;Park, Beomyoung;Kim, Donghun;Cho, Soohyun
    • Food Science of Animal Resources
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    • v.34 no.6
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    • pp.742-748
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    • 2014
  • This study was conducted to evaluate the activities of antioxidant enzyme (glutathione peroxidase (GSH-Px)) and lysosomal enzymes (alpha-glucopyranosidase (AGP) and beta-N-acetyl-glucosaminidase (BNAG)) of the longissimus dorsi (LD) muscle from Hanwoo (Korean cattle) in three freezing conditions. Following freezing at -20, -60, and $-196^{\circ}C$ (liquid nitrogen), LD samples (48 h post-slaughter) were treated as follows: 1) freezing for 14 d, 2) 1 to 4 freeze-thaw cycles (2 d of freezing in each cycle), and 3) refrigeration ($4^{\circ}C$) for 7 d after 7 d of freezing. The control was the fresh (non-frozen) LD. Freezing treatment at all temperatures significantly (p<0.05) increased the activities of GSH-Px, AGP, and BNAG. The $-196^{\circ}C$ freezing had similar effects to the $-20^{\circ}C$ and $-60^{\circ}C$ freezing. Higher (p<0.05) enzymes activities were sustained in frozen LD even after 4 freeze-thaw cycles and even for 7 d of refrigeration after freezing. These findings suggest that freezing has remarkable effects on the activities of antioxidant enzyme and lysosomal enzymes of Hanwoo beef in any condition.