• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.729-733
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• 2006

Small yellowish brown crystals were found in some concentrated oyster extracts which prepared by heating with the drip and washed water of boiled oyster in oyster processing factories. We collected those crystals by filtering the oyster extracts and analysed X ray diffraction (XRD), scanning electron microscopy (SEM) and minerals by ICP. Those were composed of moisture (8.1%), organic materials (21.6%) and inorganic materials (70.2%). Those major inorganic materials were determined as Ca (53.8%) and P (43.8%), from the ICP and elucidated those crystal as brushite $(CaHPO_4{\cdot}2H_2O)$ by XRD and SEM. Organic materials contained crude protein (33.7%) consisting of 7 amino acids. It is presumed that brushite may be formed by the reaction of excess Ca with P in the oyster extracts during concentrating process under higher temperature.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.869-875
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• 1989

For the evaluation of storage stability of kiwifruit, the conditions of CA storage were based on the following gas compositions; 2% oxygen and 2, 4, 6% carbon dioxide, respectively. The results obtained from the experiment were as follows; The flesh softening was considerably reduced at the storage atmospheres of 4% $CO_2$ plus 2% $O_2$, and fruit firmness of 3.0kg was marked in this CA condition after storage for 180 days. The concentration of $CO_2$ affected clearly on the respiration rate and organic acid compositions of kiwifruit during CA storage. The respiration rate at the storage condition of 6% $CO_2$ was lower than those at 2 and 4% $CO_2$. Quinic and succinic acid contents were obviously increased in the kiwifruit stored at all the CA conditions studied. In comparision of the developed amounts of off-flavor substances, ethanol and acetaldehyde, depended upon the concentration of $CO_2$ in the CA conditions, the larger amount were produced in the storage condition of higher concentration of $CO_3$. From the results mentioned above, it could be concluded that the optimum atmosphere combination for CA storage of kiwifruit was 4% $CO_2$ plus 2% $O_2$.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.117-121
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• 2009

Soybean curd (SC) is prepared through the elimination of water-insoluble components and molding by pressing. However, whole soybean curd (WSC) is made without the elimination of water-insoluble components and pressing. Therefore, it was considered that the components contained in WSC might be different from those in SC and we compared their contents of various components, hardness, and morphological features for this study. Ash, dietary fiber, and niacin contents were significantly higher in WSC than in SC. In addition, the carbohydrate and vitamin $K_1$ contents of WSC tended to be higher than those in SC, whereas the hardness of WSC was lower than that of SC. Moreover, electron microscopic analysis showed that the morphological characteristic of WSC consisted of considerably more fine retiform tissues in comparison to SC. Based on their compared nutrition, functional, and quality characteristics, it was suggested that WSC might be superior to SC.

• Korean Journal of Food Science and Technology
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• v.47 no.4
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• pp.425-430
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• 2015

The objective of the study was to investigate the off-flavor generated from PET water bottles and their caps by using a mass spectrometry-based electronic nose. The ion fragment data obtained from the electronic nose were used for discriminant function analysis (DFA). In the case of increased concentrations of the contamination of water, the off-flavor pattern depended on the discriminant function second score instead of the discriminant function first score. To identify the cause of off-flavor in polyethylene terephthalate (PET) bottled water, the PET bottle and its cap were analyzed by DFA. The results showed that the cap generated more volatile compounds than the bottle or mineral water did. The substances causing the off-flavor were predicted to be 2,4-di-tert-butylphenol (2,4-DTBP), nonanal, and decanal when the main peak of the mass spectrum was compared with the major ion fragments of the electronic nose. Thus, using this method, we could determine whether the PET water bottle was contaminated and whether the off-flavor resulted from contamination of the bottle cap.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.109-119
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• 1989

To improve the storage method of Kimchi, optimum ripening Kimchi for an irradiation treatment(the time of around 0.3% in total acidity of Kimchi) was irradiated by doses of 1, 2, 3 kGy with Co-60 ${\gamma}-radiation$ and stored at $10^{\circ}C$. Total aerobic bacteria increased in the beginning of storage and then decrease slowly as the number of total lactic acid bacteria increased. Total lactic acid bacteria initially loaded by $10^8\;cells/ml$ in Kimchi shortly after irradiation reduced to $10^4-10^6\;cells/ml$ with 1-3 kGy doses and decreased gradually through the whole storage period. The initial load of yeast, $10^3\;cells/ml$, increased steadily during Kimchi storage and led to more than $10^4\;cells/ml$ after 30 days of storage. While it maintained tha the load in 2-3 kGy irradiated groups after 30 days of storage was less than that at the beginning of storage. pH, acidity and volatile acid in the nonirradiated group were 4.0, 0.7% and 0.06%, respectively at the 15th day after storage, but at the 30th day after storage, 2-3 kGy irradiated groups showed different values, 4.1, 0.58-0.63%, and 0.04-0.05%, respectively. The texture(firmness) of Kimchi reduced along with storage time, and 2 kGy irradiated group proved most favourable in its texture during storage. In the sensory evaluation of Kimchi, nonirradiated group was inedible after 15 days of storage, whereas 2-3 kGy irradiated groups could proling the storage-life of Kimchi over 2 times compared with the nonirradiated Kimchi, showing the good sensory quality even after 30 days of storage.

• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.71-76
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• 1986

Changes in pH, titratable acidity, some organic acids and brix of the strawberry stored at the different levels of $CO_2$, in air were measured. The changing trends in pH and the acidity of the strawberries were not clear among the storage treatments, and pH of the strawberries in all the treatments was increased(r=0.9615) by contrast to decrease in the acidity(r=-0.8483). Ascorbic acid content of the strawberries at control lot was higher than the contents of the CA stored for the initial 2 weeks after storage. This trend was reversed after that period and the strawberries in air with 30% $CO_2$, showed the highest retention rate, 28% of the initial content after 5 weeks. Among the analyzed organic acids, malic acid was gradually decreased in all the treatments during storage and the decreasing rates of the strawberries in air with 30% $CO_2$, was somewhat stupider than those in the others. Pyruvic acid was reduced in the control lot during storage but drastically increased in the strawberries stored at the CA storage conditions between the 2nd and the 3rd week after storage, and then it was decreased.

• Korean journal of food and cookery science
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• v.9 no.1
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• pp.52-56
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• 1993

This study was examined on the change of mineral contents (Calcium, Potassium, Magnesium Zinc, Iron, Sodium, Phosphorus) in Sam-gye-tang broth cooked by various cooker and boiling time. The results were as follows; 1) In cauldron, the contents of Calcium, Potassium, Magnesium Zinc Iron Sodium, Phosphorus were increased in proportion to boiling time. In pressure cooker, the contents of Calcium, Potassium, Magnesium, Zinc are increased according to boiling time but the contents of Iron, Sodium, Phosphorus were showed the maxium value at 120 minutes and were decreased since then. 2) Ca/P was 1:0.91 in raw materials of Sam-gye-tang. But the extracting rate of Ca/P of the broth cooked in cauldron was 1:3.58∼1:4.68 and 1:2.02∼l:3.96 in pressure cooker. This rate was quite different from the recommended one of 1:1∼l:1.5. 3) In the increasing rate of minerals according to boiling time, the increasing rate of Calcium was showed similar in cauldron and pressure cooker, but Potassium, Magnesium, Sodium, Phosphorus were showed the maximum increasing rate from 30 to 60 minutes in cauldron and pressue cooker. Zinc was showed the maximum increasing rate from 120 to 150 minutes in cauldron and from 30 to 60 minutes in pressure cooker.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.503-508
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• 1990

Stews were prepared by 2 processes and 4 treatments, and stored for 3 different storage periods. The two processes were beef cooked in a stew and stored in a polyethylene container at $5^{\circ}C(P1)$ and in a barrier bag at $0^{\circ}C(P2)$. The four treatments were beef cooked alone (T1), with onions (T2), with carrots (T3) and with onions and carrots (T4). Stews in P1 were stored for 0, 2 and 4 days and stews in P2 were stored for 0, 2 and 4weeks. Cooking decreased the cephalin content by 39%. the lecithin content by 21% and most of the prolipid fatty acid concentrations as well as the fatty aldehyde levels in the phospholipids of beef from stew. Process or storage did not significantly affect the level of either phospholipids. however cooking beef with carrots seemed to exhibit some protection against hydrolysis of cephalin. P1 stews had a higher TBA-value (p<0.05) than P2 stews, and the TBA-value of P1 stews increased linearly during 4 days storage. The TBA-value was not affected (p<0.05) by treatment for any of the stews and did not change significantly during 4 weeks storage in P2 stews.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.162-166
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• 2005

Two flavonoids, 7-O-methyl-3',4'-didehydroxy quercetin (MDQ) and quercetin, isolated from Chinese propolis, which is the generic name for the resinous substance collected by honeybees from various plant sources, were tested for their antioxidant activity and protective effect against radiation-induced DNA damage in mouse lymphocytes. In antioxidant test, both compounds provided a dose-dependent scavenging effect on DPPH radical and a dose-dependent inhibitory effect on lipid peroxidation in mouse liver. Quercetin showed stronger scavenging and inhibitory effect than MDQ, and it also provided strong inhibition on superoxide anion radical generated in xanthine-xanthine oxidase system, but there was no inhibitory ability for MDQ. In comet assay using single cell gel electrophoresis, MDQ and quercetin showed a protective effect against DNA damage caused by gamma irradiation. They reduced DNA damage to 54% (p<0.01) and 53% (p<0.01) at 25 $\mu$mol, respectively. These results suggest that free radical scavenging seems to be associated with their catechol form on the B ring, and radioprotection appears to be a likely mechanism of antioxidant activity by these flavonoids.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.372-376
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• 2009

Physicochemical changes in persimmon were examined during natural organic acid fermentation. Major organic acids in raw persimmon juices were lactic acid (980 mg%) and acetic acid (245 mg%). The content of acetic acid was continuously increased during the whole period of fermentation up to 3 years. Glucose was the dominant free sugar, but the content was decreased after 20 days of fermentation. Most of the glucose was converted to ethanol until 40 days after initiation of acid fermentation. L- and a values of Hunter's color in fermented persimmon juice, which was naturally exuded from persimmon fruit as fermentation continued, increased gradually, while b value decreased. Acetic acid (1584 mg%) was the most abundant organic acid followed by lactic acid (712 mg%) and citric acid (48 mg%) in a persimmon fruit juice after completion of 3 year fermentation. A minute amount of residual free sugars, mainly glucose, even after 3 years of fermentation may cause changes in quality characteristics while storage for edible use.