• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.615-623
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• 2000

The brine Korea cabbage (BKC) with various ingredients was stored at 5$^{\circ}C$ and 15$^{\circ}C$ for 13 days to examine the changes in pH, total acidity, ascorbic, and cholrophylls. Decrease in pH and increase in total acidity in the BKC stored at 15$^{\circ}C$ were greater than in the BKC stored at 5$^{\circ}C$, indicating these changes are closely related to the storage temperature. The effect of ingredints was various; garlic, red pepper powder, and fermented anchovy juice accelerated the decrease in pH and increase in total acidity; mustard powder and leaf mustard suppressed their changes and freen onion and ginger had no effect. At both temperatures, ascorbic acid was remained at high level in the BKC with leaf mustard, but it was maintained at lowest level in the BKC with ferented anchovy juice. Degradation od chlorophylls was slow in the BKC with leaf mustard, which maintained the high level os ascorbic acid during storage. Meanwhilr the degradation of chlorophylls or production of pheophytin and pheophorbide was cinsistent with the production of acid. These results suggset that degradation of chlorophylls in a BKC was positively correlated with ascorbic acid content and the acid produced during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.655-662
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• 2000

Electron beam (EB) irradiation was applied to study microbial decontamination effects for kochujang powder by determining their microbiological and physicochemical qualities over gamma ray (GR) irradiation. The samples showed a high microbial population, such as 105~106 CFU/g of total aerobic bacteria, negative of yeasts & molds and coliforms. Total bacterial counts were decreased by 1~2 log cycles with EB irradiation at 5~7.5 kGy, and 10 kGy irradiation was enough to improve the microbiological quality by reducing populations to below 104CFU/g, which was similar to gamma energy. Such doses were effective for controlling the microbial growth in stored samples during storage for 4 months at room temperature. Decimal reduction doses (D10 value) on initial bacterial populations were 2.88~3.02 kGy in EB and 3.57~3.59 kGy in GR, which were influenced by initial populations and energy types applied. Based upon the above results, 7.5~10 kGy irradiation caused negligible changes in Hunter's color, capsaicin, fatty acid composition and organoleptic qualities. Considering the quality changes resulting from subsequent storage, such as a decrease in capsanthin content and an increase in TBA value in the samples, it is recommendable to irradiate kochujang powder at 7.5~10 kGy when used for food processing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.965-970
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• 2003

This study has been performed to develope a method for the simultaneous determination of 1,4-dioxane (DOX), epichlorohydrin (EPC), propylene chlorohydrin (PCH), ethylene chlorohydrin (ECH) and 1,3-dichloro-2-pro-panol (DCP) in polysorbates, chloline chloride, choline bitartrate, modified starch and spices by purge and trapgas chromatography. Experimental design was used to select a suitable trap by measuring the limit of detection (LOD) and to investigate the effect of temperature and salt of extraction, and the percentage of recovery in various matrix. The LOD of DOX, EPC, PCH, ECH and DCP were 1.38$\mu\textrm{g}$, 0.23$\mu\textrm{g}$, 3.30$\mu\textrm{g}$, 3.97$\mu\textrm{g}$, 20.43$\mu\textrm{g}$ respectively, by means of using Vorcarb 3000 trap with 5$0^{\circ}C$ sample sparger. Excluding EPC, the recoveries of target compounds were above 90% in all matrix. Target compounds in polysorbates (17), choline chloride (5), choline bitartrate (5), modified starch (8) and spices (25) were not detected. But 2.5 ppm of DOX was detected in Tween 80.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.754-760
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• 2006

This study was conducted to examine the quality characteristics of canned kimchi prepared by minimal thermal processing. Korean cabbage kimchi was fermented at $20^{\circ}C$ for several days up to acidity $0.5{\pm}0.1%$, was packaged in cylindrical can of 115 mL and pasteurized at low temperature. Thermal processing times based on $F_{60}$ value at geometrical center of the can were determined as 23.1, 17.7 and 12.7 min at 65, 70 and $80^{\circ}C$, respectively. The quality changes of the processed kimchi were measured during storage at $20^{\circ}C$. The pH of pasteurized kimchi was higher than that of unpasteurized control. The number of lactic acid bacteria was reduced to about $10^{2}{\sim}10^{3}$ (CFU/mL). The pasteurized kimchi product showed better texture and color values compared to the control, while resulting in the lower carotenoid and ascorbic acid contents. Kimchi preparation by minimal thermal processing had a positive effect for reduction of sour taste and sour flavor in sensory quality, but gave adverse effect in acceptability because of off-taste and off-flavor.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.6
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• pp.768-773
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• 2006

Effect of gamma irradiation on the microbiological and physicochemical characteristics of vacuum-packaged sugar-treated corns was examined to improve taste and shelf-life during storage at room or low temperature. When the vacuum-packaged sugar-treated corns were stored at $25^{\circ}C$ for 7 months, total counts and yeast and molds in the control increased approximately 2.4 and 3.5 log CFU/g, respectively but complete inactivation was observed for irradiated corns at 3 and 5 kGy. Similar results were observed at $15^{\circ}C\;and\;4^{\circ}C$ storage. There were no significant differences in hardness between irradiated sugar-treated waxy corns and control group before storage, but the hardness in control significantly increased during the storage, compared to those of irradiated corns. Also, changes in sugar content were not significant between the irradiated sugar-treated waxy corns and control during storage. Sensory evaluation for steamed-waxy corns showed that total sensory scores were higher in irradiated corns than in control, which were increased with irradiation doses. It was considered that maintaining good quality and increasing shelf-life of irradiated vacuum-packaged sugar treated corns could be possible at $15^{\circ}C$ storage for long-term period.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.4
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• pp.397-402
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• 1984

As a basic research for inhibition of enzymatic browning of apple wine, polyphenol oxidase (EC 1.10.3.1) from apple (Jonathan) was extracted, partially purified, and some properties of the enzyme and changes o( active bands by heat treatment were investigated. Optimum conditions for the enzyme reaction were pH6.5 and temperature of $30^{\circ}C$, and o-diphenol was the main substrate for the enzyme. Approximately 35% and 15% of initia lpolyphenol oxidase activity remained after heating at $60^{\circ}C$ and $70^{\circ}C$ for 1 hour, respectively. About 0.5mM of the inhibitor such as sodium metabisulfite, cysteine and ascorbic acid was required for effective inhibition of the enzyme reaction. However, EDTA was found to be a very poor inhibitor. Ethanol did not affect the enzyme activity. The number of active bands of polyphenol oxidase from apple(Jonathan) was found to be four, but two bands and one band were observed after heating at $60^{\circ}C$ and $70^{\circ}C$ for 1 hour, respectively, which showed a significant difference in thermal stability among active bands.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.139-144
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• 2006

Chestnut trees have been severely damaged by the various cankers in Korea. Field surveys for elucidating the relationships between disease occurrence and environmental factors, i.e., tree age, temperature, rainfall precipitation, direction, degree of slope, chemical properties of soils, and so on, were carried out in the chestnut tree plantations located at Gyeongnam, Jeonnam, Chungnam, and Gyeonggi-Do Province. Totally, one thousand and one hundred thirty seven trees from 36 experiment plots were investigated. Trees infected by at least one of the canker fungi were estimated up to 66%. The most severely infested area was Sunchon in Jeonnam Province with the rate of 80%, while the most lightly infested area was Kongju in Chungnam Province with 39%. Disease occurrence was found to be highly correlated with tree age. The disease occurred most frequently on trees ranged from 7 to 12 years old, while it was relatively low on trees below 5 years old or above 25 years old. Canker positions on the tree formed by the pathogenic fungi were most often at 1.6-2.0m above the ground. Over five hundreds bark samples from the canker area on the tree were collected and the pathogenic fungi were isolated. The most commonly isolated fungus was identified as Cryphonectria parasitica, the chestnut blight fungus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.4
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• pp.32-39
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• 1986

A strain of Aspergillus niger CAD 1 which produces considerable amount of beta-galactosidase was selected from extracellular beta-galctaosidase producing fungi isolated from soil. Optimal conditions for the enzyme from Aspergillus niger CAD 1 were the growth in wheat bran supplemented with 0.5% skim milk powder at $30^{\circ}C$ for 72 hrs. The crude enzyme was purified 1,387 fold through DEAE-cellulosc and Sephadex G-100 chromatographr and its recovery was 6.2%, The optimal pH and temperature for the purified enzyme were pH 4.5 ana $45^{\circ}C$, respectively. The Km and Vmax on ONPG were $3.57{\times}10^3M$ and 33.0 unit/mg protein, whereas those on lacose were $83.3{\times}10^3M$and 15.33 unit/mg protein, respectively, The activation energy for the enzyme was 9,900 cal/mol and the enzyme had no metal ion requirement for its activity and stability. The hydrolysis of lactose in skim milk, 4.8% lactose solution and acidic whey were 65%, 70% and 78% after 10 hrs incubation at $45^{\circ}C$, when 182 units of the enzyme were used 50ml of the substrate solutions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.4
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• pp.40-46
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• 1986

The beta-galactosidase of Aspergillus niger CAD 1 described in previous report was immobilized to cellulose triacetate. The optimal conditions for immobilization of the enzyme were obtained when 13%(v/v) of the soluble enzyme (349 unit/ml) was entrapped in fiber prepared from 10%(w/v) cellulose triacetate in methylene chloride. The optimal temperature and pH for the activity of the immobilized enzyme were $45^{\circ}C$ and 4.5, respectively, which stowed the same values as those of the soluble enzyme. It was found that Km of the immobilized enzyme for lacotse exhibited high value compared with that of the soluble enzyme. The immobilized enzyme showed good storage stability, reusability, and also hydrolysis of lactose when introduced into skim milk and acidic whey.