• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.594-599
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• 1988

Methods by which liquid egg could be stored in liquid state at frozen storage temperature$(-15^{\circ}C)$ with selected cryoprotectants and enzyme treatment were investiated, and quality changes in samples during storage were examined. The concentration of cryoprotectants (45% fructose and 55% glucose) to be added to egg yolk and whole egg to store them at $-15^{\circ}C$ in unfrozen state were 45.2% and 70.3%, respectively. Changes in consistency, precipitation of protein and microstructure of egg samples during storage indicated that adding cryoprotectants to liquid egg could effectively inhibit development of gelation during storage at $-15^{\circ}C$. Treating liquid egg with 0.15% papain could inhibit gelation during storage to some extent.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.197-201
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• 2006

Long-term storage technology was developed to extend shelf-life of citron (Citrus junos). Changes in quality characteristics of blanched and frozen citron peels (type A, without blanching for control; type B, blanched at $95^{\circ}C$ for 2 min; type C, blanched at $95^{\circ}C$ for 2 min, sugar added; type D, blanched at $95^{\circ}C$ for 5 min) during frozen storage were evaluated. Citron jam was prepared using frozen citron sample B, which showed the highest quality characteristics during storage, and high quality characteristics, such as yield and overall acceptability, were obtained when using 40% frozen citron, 41% sugar, 18.56% glutinous starch syrup, 0.39% pectin, and 0.05% citric acid. During storage of both blanched and frozen citron peels and citron jam made of frozen citron peel, changes in characteristics such as pH, total acids, soluble solids, and browning, were lower than those of control. Sensory evaluation for sourness, sweetness, and overall acceptability of citron jam made with frozen citron peel during storage showed higher values than those of control.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.957-963
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• 1999

Effects of cryoprotectants on protein denaturation of soybean curd, tofu, during frozen storage were examined. A whole-coagulated non-press tofu was prepared by adding 2% of isolated soybean protein to soy milk in order to prevent loss of added cryoprotectants. The cryoprotectants added were glocose, glycerol, sorbitol, propylene glycol, and tripolyphosphate. The texture characteristics of soybean curds before and after frozen storage were measured by sensory evaluation and Texture analyzer, and the results were evaluated by response surface methodology (RSM). Glucose, glycerol, sorbitol, and sodium tripolyphosphate were effective as single cryoprotectant, and the mixtures of glucose and sodium tripolyphosphate, and sorbitol and propylene glycol were also effective in minimizing textural change during freezing. Overall, the mixture of cryoprotectants were more effective than single cryoprotectant. According to the RSM, the maximum effect of cryoprotectants in minimizing textural changes during freezing was obtained with the mixture of 2.1% glucose, 6.7% glycerol, 2.1% sorbitol, 0.4% propylene glycol, and 0.3% sodium tripolyphosphate. However, considering the sensory acceptability, the optimum use of cryoprotectants in frozen tofu was 1% glucose, 2% glycerol, 1% sorbitol, 0.2% propylene glycol, and 0.5% sodium tripolyphosphate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.9
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• pp.1316-1323
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• 2016

The aim of this study was to evaluate proteolytic and antioxidant activities of fresh pineapple and kiwi juices extracted using a slow-speed masticating household juicer during low temperature storage. While over 90% of vitamin C and total polyphenols in both juices were retained after storage for 30 days at $-20^{\circ}C$, reduction of 56.8% for vitamin C and 31.9% for total polyphenols in pineapple juice were detected after storage at $4^{\circ}C$. In the case of kiwi juice, 32.9% of vitamin C and 22.4% of total polyphenols were lost. A high initial content of vitamin C in kiwi juice resulted in a slower reduction rate than that for pineapple juice. A similar result was obtained for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. Proteolytic activities of both juices were maintained efficiently with less than 10% loss during storage for 30 days at $-20^{\circ}C$. Protease stability of pineapple juice was better than that of kiwi juice during storage at $4^{\circ}C$, and the same result was obtained when boiled chicken breast was used as a substrate. From these results, when storing pineapple and kiwi juices, which are widely used as a natural meat tenderizer and digestive aid, cold storage at $-20^{\circ}C$ seemed to be more suitable for maintaining antioxidant and proteolytic activities than cold storage at $4^{\circ}C$.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.216.1-216
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• 2003

본 연구에서는 시판 찹쌀가루와 실험실에서 제조한 찹쌀가루를 사용하여 만든 경단의 품질특성을 관능검사와 기계적인 측정을 통하여 비교함과 동시에 실험실에서 제조한 가루의 경우에는 찹쌀가루의 냉동저장이 경단의 품질특성에 미치는 영향을 검토하였다. 또한 경단제조후 보관온도와 시간경과에 따른 품질특성의 변화도 기계적인 측정을 통하여 살펴보았다.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.169-176
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• 2005

The decreasing pattern of underground temperature measured at 'Gonjiam cold storage cavern' during 7 years which was the first commercial scale underground food storage cavern in Korea was analyzed. The variation of energy consumption was discussed by comparing the consumed energy at the initial operation stage with that at later stage, when the temperature distribution reached a stabilized condition. The point to be considered at the design stage was also discussed by comparing the required refrigerator capacity at the initial operation stage with that at later stage. The extra energy to freeze the groundwater contained in pore space was discussed by analyzing the changing pattern of the rock temperature. The variation of measured rock temperature was compared with the estimated temperature using a numerical code, FLAC. The accuracy of the numerical estimation was discussed by comparing the heat flux measured by the operation time of the refrigerator with that estimated numerically.

• Journal of the Korean Society of Food Culture
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• v.19 no.2
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• pp.209-216
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• 2004

To investigate physico-chemical changes of mashed red repper and red pepper powder during frozen storage, we analyzed the quality of samples after mashing, mashing and blanching, mashing and addition of vitamin C, mashing and addition of NaCl. The most important quality factor of red pepper is red color. $\alpha$ value of red pepper powder of Pochungchun was 31.51. These results showed that those processing methods were effective to preserve red color. Capsanthin contents of mashed red pepper treated with vitamin C were decreased 1.8% after 180 days of frozen storage. This decrease was the least, showing that addition of vitamin C helped retaining capsanthin contents. Capsaicin and dihydrocapsaicin contents in Pochungchun powder ore decreased 11.9 and 18.3% during frozen storage respectively. These results showed that capsaicin was more stable than dihycrocapsaicin during frozen storage. Generally capsaicin and dihydrocapsaicin in the Pochungchun red pepper frozen-stored after mashing were less decreased than red pepper powder, and addition of vitamin C to the mashed red pepper was the most effective to retain capsicin and dihydrocapsaicin than others. The content of vitamin C in the red pepper frozen-stored after masking and blanching was 12.0 mg/100g, compared with 44.0 mg/100g in the sample stored after only mashing. This suggested that blanching process destroyed vitamin C in the mashed red pepper. Addition of salt in the mashed red pepper showed the same inclination. But, addition of vitamin C to the mashed red pepper was decreased 32.9% compared with 69.0% in the mashed red repper during frozen storage. Theser results indicated that addition of vitamin C could retain vitamin C in the mashed red lopper.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1438-1443
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• 2009

The effects of adding additives such as gum, emulsifier, and enzyme both individually and as mixtures to frozen rice bread dough on baking quality were examined. Rice flours containing 17% vital gluten, and gum/emulsifier/enzyme blends were mixed and stored in a freezer at $-20^{\circ}C$ for 4 weeks. The rice doughs were removed from the freezer, thawed, and then followed the rice baking procedure. The dough freezing and frozen storage resulted in decreased volume of rice bread. The addition of guar gum/sodium stearoyl lactylate (SSL)/fungal $\alpha$-amylase blend improved volume of the rice bread obtained from rice dough during frozen storage. An increase in firmness of crumb was observed in rice breads during 3 days of storage at $25^{\circ}C$. Compared to the control dough without additives, addition of guar gum/ SSL blend or guar gum/ SSL/ fungal $\alpha$-amylase blend into frozen dough significantly reduced the crumb firmness of rice bread, indicating a significant antistaling effect.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.624-631
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• 1996

Effect of fluctuation range and intervals of defrosting temperature on quality of frozen foods stored in a domestic refrigerator equipped with an automatic defrost system was evaluated. As defrost system was operated, temperatures of domestic refrigerators were elevated from $-18^{\circ}C\;to\;-5^{\circ}C\;and\;-15^{\circ}C$, and fluctuation intervals were l6 hrs and 30 hrs, respectively. Quality deterioration such as protein denaturation, vitamin loss, exudate production and changes in appearance of frozen foods was minimized by reducing temperature oscillation during storage. Considerable effects of thermal oscillation on ice crystal sizes were observed for frozen beef tissue and ice cream. TTI (time temperature indicator) system also proved that the temperature control of defrost system in domestic refrigerator can improve the quality of foods during storage.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.459-465
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• 2002

To obtain the basic data for commercial 10% salted egg yolk for mayonnaise preparation, 3 types of egg yolks [pasteurized egg yolk (Yolk A)-not salted, pasteurized before salting (Yolk B)-salted, and pasteurized after salting (Yolk C)-salted] were prepared, and the changes in quality characteristics of these egg yolks with frozen storage were tested. The results obtained were as follows; Yolk A gelatinized during frozen storage, thus could not used for mayonnaise preparation. The viscosity of the egg yolk increased $3{\sim}5$ times after salting. Viscosity of the salted egg yolk increased with frozen storage time. Viscosity of Yolk B was higher at $-20^{\circ}C$ than $-15^{\circ}C$. Viscosity of Yolk C, however, was higher at $-15^{\circ}C$ than $-20^{\circ}C$. Frozen storage of pasteurized salted egg yolk showed some effects on the emulsification capacity. The effect, however, was smaller than that of unpasteurized salted egg yolk. Microbes of salted egg yolk were decreased with frozen storage, but there was no difference between Yolk B and Yolk C. It was suggested that commercially pasteurized 10% salted egg yolk for mayonnaise preparation can be successfully stored for 12 months at the temperature of $-15{\sim}-20^{\circ}C$.