• Korean Journal of Food Science and Technology
• /
• v.30 no.6
• /
• pp.1448-1455
• /
• 1998

Fermented milk was prepared from milk or mixture of milk and apple juice/grape juice, and it was freeze dried. pH change and growth of Lactobacillus acidophilus (KCTC 2182) during freeze drying were studied. The effects of freeze drying on sensory evaluation and volatile aroma compounds in freeze dried sample or reconstituted sample were also studied. Freezing and freeze drying did not affect pH of fermented milk. Number of viable cells of L. acidophilus was markedly reduced during freezing or freeze drying. When number of viable cells in original fermented milk was considered as 100%, survival ratio of viable cells after freezing was $64.5{\sim}85.2%$ and that after freeze drying was $10.0{\sim}21.1%$. When sensory properties of original fermented milk prepared from juice-milk (ratio 15:35) were compared with those of freeze dried/reconstituted sample, sensory properties of original sample were better than those of freeze dried/reconstituted sample. Ethanol, diacetyl, butanol and acetoin were detected in all of original samples and freeze dried/reconstituted samples while acetone was detected in samples containing high amount of grape juice. Volatile aroma compounds in original fermented milk were reduced during freeze drying. L. acidophilus produced ethanol, diacetyl and acetoin during fermentation.

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

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.20 no.6
• /
• pp.957-972
• /
• 2018

Tunnels constructed in cold regions can cause serious defects such as cracks and leaks due to external temperature changes in the portals and vents. In order to prevent the freezing damage of the tunnel, appropriate measures should be applied to the section where the freeze damage is concerned. However, the specific criteria and contents for judging whether or not the anti-freeze measures are applied are not presented. In this study, the laboratory freezing tests on the temperature changes of the concrete specimens under freezing conditions were carried out. And the freeze-thaw repetition cycle (F), which can judge the possibility of freezing damage, were presented based on the heat transfer quantity (W) by experimental results of case studies. Also, we propose a classification of cold regions considering the climatic characteristics of Korea for using it to efficient design and maintenance.

• Food Engineering Progress
• /
• v.22 no.4
• /
• pp.315-320
• /
• 2018

This study examined the effects of drying methods of Aronia melanocarpa on contents of total polyphenols and flavonoids, antioxidant activity and anti-inflammatory activity. As a result, freeze-dried aronia extract (FDAE) significantly exhibited higher contents of total polyphenols and flavonoids (155.76 mg GAE/g and 105.70 mg QE/g) than hot-air dried aronia extract (HDAE) (134.93 mg GAE/g and 82.29 mg QE/g). Also, FDAE showed greater antioxidant activity than HDAE in both DPPH and ABTS. For anti-inflammatory activity, NO production from lipopolysaccharide activated RAW264.7 cell reduced at a dose-dependent manner in both FDAE and HDAE. However, reduction rate of NO production is higher in FDAE (62.7%) than in HDAE (33.5%). These results suggest that comparatively, freeze-drying is a better method for preserving the antioxidant and anti-inflammatory activities and of aronia.

• Food Science of Animal Resources
• /
• v.20 no.3
• /
• pp.192-198
• /
• 2000

홀스타인 도체를 두쪽으로 나누어 한쪽은 진공포장하여 1$^{\circ}C$에 냉장하고(냉장육), 나머지 한쪽은 함기포장하여 -2$0^{\circ}C$에 동결하였다. (동결육). 두시료의 기호성을 저장 20일, 40일, 및 60일째에 비교하였으며, 비단백태 질소화합물 함량의 상관관계를 검토하였다. 또. 냉장육의 진공포장을 개봉하거나. 동결육을 해동한 후 재냉장한 것에 대해서도 기호성을 비교하였다. 생육향의 경우, 20일과 40일에는 냉장육이 우수하였으나 60일에는 오히려 동결육이 우수하여 진공포장육은 냉장기간이 길어지면서 산소 부족으로 인한 생육향 생성이 적은 현상을 보였다. 두 시료를 재냉장한 후의 생육향도 마찬가지였다. 저장 20일과 40일에현저한 차이는 아니지만 냉장육이 우수한 반면 60일에는 동결육이 우수하였다. 연도는 저장기간에 관계 없이 냉장육이 우수하였고, 해동 후 재냉장에 의해서 향상되었다. 가열육의 기호성은 저장기간에 관계없이 냉장육이 우수하였으며 20일(p<0.01)에 가장 큰 차이를 보였다. 재냉장한 우육의 기호성은 저장 20일(p<0.05)과 40일(p<0.01)의 것은 냉장육이 우수한 반면 60일의 것은 동결육이 우수하였다. 냉장육의 기호성과 비단백태 질소화합물의 상관관계는 유의성이 없었으며, 동결육의 경우 inosin의 유의적인 상관관계(r=0.48)를 보였다.

• Journal of Embryo Transfer
• /
• v.21 no.1
• /
• pp.1-5
• /
• 2006

본 연구는 개 채취 정액의 동결후의 생존성과 신선 및 동결 정자의 capacitation, acrosome reaction과 생존성을 조사하고, 아울러 신선 및 동결 정액을 자연 발정 또는 발정 유기 암캐 에게 인공수정 후 임신율을 조사하였다. 개 채취 정액의 동결 융해 후의 생존성은 $64.5{\pm}2.30%$로서 신선 정액의 생존성에 비해 유의하게 낮게 나타났다(p<0.05). 신선 및 동결 정액의 capacitation, acrosome reaction 및 생존성은 각각 $52.5{\pm}4.5%,\;9.5{\pm}0.6%,\;68.8{\pm}4.5%$ 및 $16.2{\pm}3.2%,\;3.2{\pm}0.5%,\;24.5{\pm}2.5%$로 나타났다. 신선 및 동결 정액을 자연 발정 또는 발정을 유기한 암캐에 인공수정했을 때 임신율은 각각 50.0% 및 33.3%로서 동결 정액을 이용했을 때 임신율이 신선 정액에 비해 낮은 임신율을 나타냈다.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
• /
• 2003.10a
• /
• pp.179.1-179
• /
• 2003

본 연구는 각종 영양성분과 기능성 물질을 함유한 식용마의 소비확대와 새로운 가공식품을 개발하고자, 당절임한 식용 마의 건조방법에 따른 물성 및 일반 성분의 변화를 조사하였다. 동결건조한 당절임 식용마의 명도는 높았고 적색도와 황색도는 열풍 및 진공 건조한 것에 비해 낮았으며, 수분함량과 재수화율은 동결건조한 것이 높게 나타났다. 수용성 단백질은 동결건조한 것이 6.43mg/100g으로 가장 낮았으며 총당과 환원당의 함량은 건조방법에 따라 뚜렷한 차이가 없었다. 주요 유기산은 malic, acetie, citric acid 이었고, acetic, citirc acid는 열풍 및 진공 건조한 것이 많았으나 malic acid는 동결 건조한 것이 월등히 높게 나타났다. 구성아미노산은 진공 건조한 것에 많았으며, 유리아미노산은 큰 차이가 없었다. 총 비타민 C함량도 별다른 차이가 없었으나 환원형 비타민 C는 동결이 산화형 비타민 C는 열풍 및 진공 건조한 것이 높게 나타났고, 무기질 함량은 K, Na, Mg의 함량이 많았다. 마 스낵의 관능검사에서는 열풍 및 진공건조에 비해 동결 건조한 것이 우수한 것으로 평가되었으며, 전자현미경적 관찰에서는 열풍 및 진공 건조한 것은 세포와 세포벽의 형태를 찾아 볼 수 없었으나 동결 건조 한것은 세포의 형태와 세포벽의 파괴가 일어나지 않았다. 본 연구는 당절임한 식용 마의 건조 방법에 따른 물성 및 성분의 변화를 조사한 결과, 동결건조한 것이 품질이 우수하였고, 영양성과 기능성을 함유한 마의 가공 식품의 개발의 가능성을 제시한다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.1D
• /
• pp.33-39
• /
• 2012

More and more pavements are suffering from damage these days due to the below-zero winter temperatures and frequent snowfalls. From this research, the freeze-thawing mechanisms of pavements will be observed, and the freeze-thawing resistance of porous asphalt concrete mixture is to be evaluated according to various assessment methods. The investigation was conducted through applying rigid and flexible pavements to freeze-thawing resistance experiments, which include various experiments such as deformation rate measurements, Lottman tests, repeated cyclic freeze-thawing experiments, stripping resistance tests and so on. Test results revealed that the porous asphalt concrete had less deformations according to temperatures compared to dense-graded asphalt concrete due to the 20% void gap. In addition, according to the freeze-thawing repetition experiments which are effected by moisture, the porous asphalt concrete mixture showed superior resistance to repeated cyclic freeze-thawing compared to other asphalt concrete mixtures due to the drainage and the voids within the specimen.

• Korean Journal of Food Science and Technology
• /
• v.34 no.1
• /
• pp.91-95
• /
• 2002

Effects of freeze-drying time on the microbiological, sensory, and other characteristics of freeze-dried kimchi were investigated to optimize freeze-drying time for kimchi. Quality attributes of freeze-dried kimchi, including number of lactic acid bacteria (LAB), pH, sensory properties, brittleness, rehydration property, moisture content, and microstructure of Chinese cabbage were observed for 24, 48 and 72 h, respectively. Number of LAB and pH of the kimchi freeze-dried for 24 h were significantly changed in comparison with those of the kimchi not freeze-dried. However, further freeze-drying did not change markedly number of LAB and pH. Overall acceptability of the sample freeze-dried for 48 of 72 h was better than that of the sample freeze-dried for 24 h. As freeze-drying time increased, brittleness of the dried sample increased, and rehydration property was improved while dried weight and moisture content of the sample decreased. In conclusion, the sample freeze-dried for 48 h was better than the sample freeze-dried for 24 or 72 h, based on sensory properties and other characteristics.

• Korean Journal of Poultry Science
• /
• v.14 no.2
• /
• pp.145-151
• /
• 1987

In order to select the optimum freezing condition for the minimization of physico -chemical changes such as protein denaturation, lipid oxidation and pH change, the effect of freezing rates on the poultry meat quality changes was studied during frozen storage at -20$^{\circ}C$. Results obtained from the experiments are as fellows. When chicken breast and leg meat were frozen at above -3cm/hr or the freezing rate, pH change during frozen storage was minimal Although TBA value and free ratty acids were increased during frozen storage, the effect of freezing rates was different depending on muscle types. In terms of protein extractability, the extractability of salt soluble protein and water soluble protein were the highest at above -3cm/hr of the freezing rate during frozen storage. This trend was more obvious with breast meat than leg meat. Considering the above - described results, above -3cm/hr of the freezing rate seemed to be the optimum freezing condition for chicken meat because or the least pH change, low TBA value and high protein extractability.