• Journal of Nutrition and Health
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• 제50권2호
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• pp.133-141
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• 2017

Purpose: The objective of this study was to examine the association of temperature-fluctuation with freshness quality in various foods. Methods: We investigated the effects of storage conditions on antioxidant activities of cherries and romaine lettuce during storage at $0.7{\pm}0.6^{\circ}C$, $1.2{\pm}1.4^{\circ}C$, and $1.6{\pm}2.8^{\circ}C$. Cherries and romaine lettuce were stored for a period of 9 days and 7 days, respectively. We also analyzed the effects of storage conditions on fresh quality of beef and salmon during storage at $-0.3{\pm}0.8^{\circ}C$, $-0.6{\pm}2.3^{\circ}C$, and $-1.5{\pm}4.4^{\circ}C$. Both of them were stored for a period of 14 days. Results: The amount of water loss was highest in beef, and the microbial count was also the highest at $-1.5{\pm}4.4^{\circ}C$. In the case of salmon, there was no difference in water loss according to storage, and TBA value was significantly increased at $-1.5{\pm}4.4^{\circ}C$. Moisture retention was the highest at $0.7{\pm}0.6^{\circ}C$ in both romaine lettuce and cherry samples. The contents of polyphenol and flavonoid were significantly higher in cherries, and content of polyphenols in romaine lettuce was significantly higher at $0.7{\pm}0.6^{\circ}C$ (p < 0.05). DPPH activity decreased in the order of $0.7{\pm}0.6^{\circ}C$ > $1.2{\pm}1.4^{\circ}C$ > $1.6{\pm}2.8^{\circ}C$ over 7 days. Conclusion: The results indicate that temperature-fluctuation may affect qualities of foods stored in a refrigerator.

• Journal of Bio-Environment Control
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• 제23권1호
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• pp.39-42
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• 2014

The objective of this study was to estimate cardinal temperatures for germination of lettuce (Lactuca sativar L.) using bilinear, parabolic, and beta distribution functions. Seeds of lettuce were germinated in a growth chamber at 7 constant temperatures: 10, 14, 16, 20, 24, 28, and $32^{\circ}C$. Four replicates of 100 seeds were placed on two layers of filter paper in a 9 cm petri-dish. Radicle emergence of 1 mm was scored as germination. The time course of germination was modeled using a logistic function. These minimum, optimum, and maximum temperatures were estimated by regression of the inverse of time to 50% germination rate against the temperature gradient. In bilinear function, minimum, optimum, and maximum temperatures were $7.9^{\circ}C$, $23.3^{\circ}C$, and $28.0^{\circ}C$, respectively. In parabolic function, minimum, optimum, and maximum temperatures were $9.7^{\circ}C$, $19.5^{\circ}C$, and $29.4^{\circ}C$, respectively. In beta distribution function, minimum, optimum, and maximum temperatures were $3.7^{\circ}C$, $20.7^{\circ}C$ and $32.0^{\circ}C$, respectively. Minimum, optimum, and maximum ranges of temperatures were $3.7{\sim}9.7^{\circ}C$, $19.5{\sim}23.3^{\circ}C$, and $28.0{\sim}32.0^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• 제35권1호
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• pp.23-32
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• 1998

Al2O3/Al composites were produced by immersing the sintered silica preform in molten aluminum which contained magnesium as impurity. Three distinct regions existed in the penetration behavior of molten me-tal with changing the reaction temperature. These regions are denoted as low temperature regime(75$0^{\circ}C$-85$0^{\circ}C$) intermediate regime(90$0^{\circ}C$-95$0^{\circ}C$) and high temperature regime(100$0^{\circ}C$$\leq$) In the low temperature regime the penetration speed of molten aluminum increased with increasing reaction temperature whereas it decreased in the intermediate regime due to the phase transition of alumina formed by displacement reac-tion. In the high temperature regime the penetration speed of molten aluminum was the highest at 100$0^{\circ}C$ which was 3.6 mm/hr But above 105$0^{\circ}C$ molten aluminum did not penetrate into the silica preform because of the formation of a dense spinel layer at the preform surface by magnesium in molten Al.

• Journal of the Korean Society of Food Science and Nutrition
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• 제31권1호
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• pp.45-49
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• 2002

This study was conducted to enhance the value of chamnamul (Pimpinella brachycarpa (Komarov) $N_{AKAI}$) as an useful food resource. Hunter L, a, b values (lightness, redness, yellowness) of chamnamul leaf were 33.28$\pm$1.94, -10.98$\pm$0.74, 14.05$\pm$1.29 and shearing force was 2745.2g. Contents of tannin and dietary fiber were 100.9 mg%, 24.0% (freeze drying base). The minerals identified in chamnamul were Ca 7.85 g/kg, K 76.31 g/kg, Mg 4.78g/kg, Fe 0.35g/kg, Na 2.35 g/kg. Chamnamul kimchi was packed in polyethylene film (200g) and fermented at 2$0^{\circ}C$ and 4$^{\circ}C$. In color changes kimchi fermented at 2$0^{\circ}C$ showed more increase in Hunter L, a, b values than kimchi fermented at 4$^{\circ}C$. The pH of kimchi decreased and acidity increased with storage time at both temperature. Ascorbic acid contents decreased sharply with storage time. Loss of ascorbic acid contents was about 81.9% in kimchi fermented at 2$0^{\circ}C$ after 5 days, and kimchi fermented 4$^{\circ}C$ lost 77.3% of ascorbic acid after 30 days. Also reducing sugar contents decreased with storage time at 2$0^{\circ}C$ and 4$^{\circ}C$. The results of sensory evaluation showed that optimum ripening time of chamnamul kimchi was 1~3 days at 2$0^{\circ}C$ and more than 20 days at 4$^{\circ}C$.>.

• The Korean Journal of Malacology
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• 제16권1_2호
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• pp.17-20
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• 2000

Effect of predation of starfish Asterias amurensis and Asterina pectinifera under different water temperature in the recirculating seawater vessel was conducted at the invertebrate culture laboratory of Yosu National University from February 1 to February 25, 2000. The highest activity of Asterias amurensis and Asterina pectinifera according to water temperature was obtained at 14$\^{C}$ and 22$\^{C}$. The average individual numbers of Anadara broughtonii predated by Asterias amurensis and Asterina pectinifera were 2.20 and 1.60 at 6$\^{C}$ , 3.60 and 2.00 at 10$\^{C}$, 7.20 and 2.50 at 14$\^{C}$, 3.40 and 6.80 at 22$\^{C}$, 0.80 and 3.90 at 26$\^{C}$, respectively.

• Journal of Food Hygiene and Safety
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• 제3권1호
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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.

• Korean Journal of Agricultural Science
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• 제22권1호
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• pp.49-53
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• 1995

The tea red spider mite has recently outbroken as the major pest of tea at tea plantation area in southern part of Korea. This study was carried out to investigate some development of the tea red spider mite. The results were summarized as follows: 1. The body length and width of adult female and male were 0.40mm and 0.22mm, and 0.31mm and 0.20mm, respectively. 2. Durations of immature stage of females were 24.8 days at $16^{\circ}C$, 17.0 days at $20^{\circ}C$, 11.0 days at $24^{\circ}C$, 8.2 days at $28^{\circ}C$, and 6.7 days at $32^{\circ}C$. 3. The average longevities of female of the tea red spider mite were 31.5 days at $16^{\circ}C$, 13.4 days at $20^{\circ}C$, 8.4 days at $24^{\circ}C$, 7.8 days at $28^{\circ}C$, and 5.8 days at $32^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• 제24권5호
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• pp.752-757
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• 1995

The effect of fermentation temperature on the changes of pH, acidity, salt content, color and vitamin C of mustard leaf kimchi during various storage days was investigated. The conditions of fermentation temperature were set at $4^{\circ}C$ (sample A) and $20^{\circ}C$ (sample B), and $4^{\circ}C$ after keeping at $20^{\circ}C$ for 12 hours(sample C) and $20^{\circ}C$ for 36 hours(sample D). As the fermentation proceeded, pH of sample stored at low temperature(sample A) was drop ped gradually from initial pH of 5.24 but there was great pH drop in the sample stored at high temperature(sample B, D). The salt content of the sample B at high temperature increased remarkably, and then the values showed D > A > C. The Humter values of L and a increased at the optimum ripening period, the higher the initial fermentation temperature(B) and the later the initial fermentation time at $20^{\circ}C$ those values, then decreased. The Hunter value of b constantly increased until day of 108. As fermentation time passed, the content of total vitamin C decreased to the range of 9.0mg% to 14.0mg% up to 24 days of fermentation, and at the optimum ripening period, it increased to the range of 14.0mg% to 22.0mg%, and at the fermentation period(until day 108), it decreased gradually.

• Korean Journal of Animal Reproduction
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• 제11권3호
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• pp.161-169
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• 1987

This experiment was carried out to investigate the optimal cooling rate and the plunging temperature into liquid nitrogen of the 8-cell hamster embryos. The female hamsters were induced to superovulate by intraperitoneal injection of 30 i.u. PMSG. Embryos were flushed from oviduct and uterine horn. Embryos were frozen and incubated with a modified Dulbecco's phosphate buffered saline, and equilibrated with 1.5M-dimethyl sulfoxide by a 3-step procedure. The cooling rate of samples was 1$^{\circ}C$/min from room temperature to -5$^{\circ}C$ and the samples were seeded at -5$^{\circ}C$. The plunging temperatures into liquid nitrogen were -20, -25, -30, -35, -40, -45, -50 and -55$^{\circ}C$ at 0.3$^{\circ}C$/min, 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. This mean numbers of ovulation points and recovered embryos were 59.4 and 48.4 appearing 81.6% recovery rate. The percentage of 8-cell embryos in recovered embryos was 68.2. The survival rates of embryos plunged at -45$^{\circ}C$ were 73.5% at 0.3$^{\circ}C$/min, 44.8% at 0.5$^{\circ}C$/min and 30.3% at 1$^{\circ}C$/min cooling rates, respectively. The survival rates at 0.3$^{\circ}C$/min were significantly high. Under the condition of 0.3$^{\circ}C$/min cooling rate, the survival rates of embryos according to the plunging temperature were 70.0% and 73.5% at -40 and -45$^{\circ}C$, and those were higher than other plunging temperatures. Under the condition of 0.5$^{\circ}C$/min and 1$^{\circ}C$/min cooling rates, the survival rates according to the plunging temperatures were lower than the cooling rate of 0.3$^{\circ}C$/min, showing the similar tendency at all the plunging temperatures. In conclusion, 8-cell hamster embryos showed the best survival rates at 0.3$^{\circ}C$/min cooling rate and -45$^{\circ}C$ plunging temperature.

• Food Science and Preservation
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• 제20권2호
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• pp.141-150
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• 2013

For the investigation of the quality loss of mulberry during distribution, the deterioration rate, microorganism growth, and sensory quality of mulberry kept at 20, 10 and $0^{\circ}C$, respectively, were investigated. Based on the results, the optimum temperature for extending the freshness of mulberry was examined in the temperature range of -1.5 to $1.5^{\circ}C$. The level of mold in the mulberry kept at 20 and $10^{\circ}C$, respectively, was much higher than that kept at $0^{\circ}C$. The quality of the mulberry deteriorated seriously after two days at $20^{\circ}C$, after six days at $10^{\circ}C$, and after 12 days at $0^{\circ}C$. The marketability of mulberry as determined via sensory evaluation was much more prolonged by decreasing the keeping temperature from 20 to $0^{\circ}C$. To extend the freshness of mulberry using these results, the optimum temperature was evaluated at the range of -1.5 to $1.5^{\circ}C$ for 25 days. During storage, the changes in the color and pH of the berry were not significantly different by storage temperature, but the microbial levels and deterioration rate increased in the order of 1.5, 0, and $-1.5^{\circ}C$. In particular, the firmness of the mulberry decreased rapidly at $1.5^{\circ}C$, showing a significant difference from the others. The titratable acidity and sugar contents decreased gradually at all the applied temperatures. The anthocyanin content decreased sharply at $1.5^{\circ}C$ but gently changed at $-1.5^{\circ}C$. Through the sensory results of this study, it was adjudged that the marketability of mulberry could be maintained about 0.7 times at $1.5^{\circ}C$ and 1.3 times at $-1.5^{\circ}C$ compared with the marketability at $0^{\circ}C$, respectively.