• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.373-379
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• 1990

Lactic acid bacteria(LAB) were isolated from fermenting Kimchi and were cultivated in filter-sterilized Chinese cabbage juice individually or in combination. LAB isolated were Lactobacillus leichimannii, Lac. fermentum, in addition to the already known Leuconostoc mesenteroides, Lac. plantarum, lac. brevis and pediococcus pentosaceus. Lac. leichimannii, Lac. fermentum and Lac. sake, the early lactobacilli, were high in number exceeding $10^4cells/ml$ at 0 time and multiplied up to $10^9cells/ml$ altogether at the 3rd day of kimchi fermentation. When the representative LAB were cultivated singly in Chinese cabbage juice with or without 3.0% NaCl, one strain of Leu. mesenteroides and La. leichmannii were not different in acid producing ability while the other strain of Leu. mesenteroides and Lac. fermentum Lac. plantarum, produced less acid when NaCl was present. When the bacteria in combination were cultivated in Chinese cabbage juice with 3.0% NaCl, the presence of Leu. mesenteroides was essential to eliminate the lag phase in acid production with higher amounts of acid produced than without. The total number of lactobacilli in the mixture of kimchi ingredients was about $2.9{\times}10^4 cells/ml$ while the number of Lac. plantarum was 7.3 cells/ml. The number of Lac. plantarum in individual ingredients were normally in the range between $0.0{\sim}240cells/g$ except garlic sold in ready-to-use form with $9.0{\times}10^3 cells/g$.

• Korean Journal of Food Science and Technology
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• v.18 no.5
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• pp.376-381
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• 1986

A hypothesis that Korean home-made fermented soybean products are brown-pigmented in large part by contaminated bacteria is proposed. Twenty six strains of bacteria forming brown pigments in the presence of L-tyrosine were isolated from home-made soybean paste. They were characterized and all were identified as strains of Bacillus subtilis. The isolates produced dark brown to brownish black pigmentation on yeast extract-peptone-glucose agar (YPGA) supplemented with 0.1% L-tyrosine in 72 hours but not on YPGA. They also caused different depress of lighter pigmentation on potato dextrose agar and nutrient agar. When an arbitrarily chosen pigmenting isolate was cultivated in a liquid medium supplemented with L-tyrosine, it began to produce pigments only after cell growth stopped. The tyrosinase enzyme was extracted and the enzyme activity was measured by using L-tyrosine and 3-hydroxytyrosine (L-dopa) as substrates. The crude enzyme preparation porduced pigments at rates of $2.1\;{\times}\;10^{-3}\;and\;5.0\;{\times}\;10^{-3}$ optical density units/min measured at 490㎚ for tyrosine and dopa, respectively. Possible content of L-tyrosine in a soybean paste formula was calculated.

• Ocean and Polar Research
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• v.26 no.3
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• pp.439-451
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• 2004

Total solar irradiance (750), total UV irradiunce (TUV) and erythemal UV irradiance (EUV) measured at King Sejong station $(62.22^{\circ}S,\;58.78^{\circ}W)$ in west Antarctica have been used together with total ozone, cloud amount and snow cover to examine the effects of ozone, cloud and snow surface on these surface solar inadiunce over the period of 1998-2003. The data of three solar components for each scan were grouped by cloud amount, n in oktas $(0{\leq}n<3,\;3{\leq}n<4,\;4{\leq}n<5,\;5{\leq}n<6,\;6{\leq}n<7\;and\;7{\leq}n<8)$ and plotted against solar zenith angle (SZA) over the range of $45^{\circ}\;to\;75^{\circ}$. The radiation amplification factor (RAE) is used to quantify ozone effect on EUV. RAF of EUV decreases from 1.51 to 0.94 under clear skies but increases from 0.94 to 1.85 under cloudy skies as SZA increases, and decreases from 1.51 to 1.01 as cloud amount increases. The effects of cloud amount and snow surface on EUV are estimated as a function of SZA and cloud amount after normalization of the data to the reference total ozone of 300 DU. In order to analyse the transmission of solar radiation by cloud, regression analyses have been performed for the maximum values of solar irradiance on clear sky conditions $(0{\leq}n<3)$ and the mean values on cloudy conditions, respectively. The maximum regression values for the clear sky cases were taken to represent minimum aerosol conditions fur the site and thus appropriate for use as a normalization (reference) factor for the other regressions. The overall features for the transmission of the three solar components show a relatively high values around SZAs of $55^{\circ}\;and\;60^{\circ}$ under all sky conditions and cloud amounts $4{\leq}n<5$ and $5{\leq}n<6$. The transmission is, in general, the largest in TUV and the smallest in EUV among the three components of the solar irradiance. If the ground is covered with snow on partly cloudy days $(6{\leq}n<7)$, EUV increases by 20 to 26% compared to snow-free surface around SZA $60^{\circ}-65^{\circ}$, due to multiple reflections and scattering between the surface and the clouds. The relative difference between snow surface and snow-free surface slowly increases from 9% to 20% as total ozone increases from 100 DU to 400 DU under partly cloud conditions $(3{\leq}n<6)$ at SZA $60^{\circ}$. The snow effects on TUV and TSO are relatively high with 32% and 34%, respectively, under clear sky conditions, while the effects changes to 36% and 20% for TUV and TSO, respectively, as cloud amount increases.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.186-191
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• 1985

The effect of gamma irradiation on the physicochemical properties of chicken meat and its sensory quality were investigated during 41 days of storage at 3 to $4^{\circ}C$ following irradiation of 5 to 10 kGy. Immediately after irradiation, the water holding capacity of chicken meat decreased slightly with the increase of irradiation dose, whereas during storage, the water holding capacity of irradiated groups was superior to that of the nonirradiated ones. With increasing the irradiation dose and storage time, the TBA values of irradiated groups were higher than those of nonirradiated ones. The volatile basic nitrogen content of nonirradiated group markedly increased over 20mg% by microbial spoilage from the 10th day of storage, however, the irradiated groups of over 8 kGy showed only the 16 to 18mg% until 41 days of storage. The irradiated groups had a slight irradiation-odour that dissipated during up to 3 days of storage, and also they showed a slight pink discoloration in the carcasses and this tendency was much more pronounced with increasing irradiation dose. The nonirradiated group gave off an off-odour due to the spoilage around 5 to 7 days of storage and showed a change in meat appearance, while the irradiated groups of over 5 kGy maintained a fresh state during the 25 to 30 days of storage.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.170-174
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• 1985

This study was intended to develop a sanitary and economic storage method using gamma irradiation for chicken. The samples, which were irradiated with doses of 0, 5, 8 and 10 kGy and stored at 3 to $4^{\circ}C$ for 41 days, were subjected to an investigation of the sterilizing effect on microorganisms. In the number of microorganisms contaminated, psychrotrophiles, mesophiles and thermophiles were $7.8{\times}10^5,\;3.6{\times}10^5$ and $1.1{\times}10^3$ per gram of the samples, respectively, and yeast & mold and coliform group were $3.0{\times}10^3$ and $2.1{\times}10^3$ per gram of the samples, respectively. Also, other enteric bacilli were isolated up to 90% out of total test groups on a selective medium(S-S agar). The number of total bacteria was reduced by over 2 to 4log cycles with an irradiation of 5 kGy to 10 kGy, and an irradiation treatment of over 5 kGy was shown to be effective for the radurization of yeast & mold, coliform group and other enteric bacilli. Thus, it was possible to extend the microbiological self-life of chicken for about 2 to 7 weeks compared with the control.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.188-191
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• 1991

A study was carried out to investigate the control effect of sodium and potassium phosphates, sodium citrate and three different salts mixtures on kimchi fermentation when they were added into half-fermented kimchi in the concentration range of $0.001{\sim}0.01\;M$. The salts mixtures added were sodium phosphates mixture(CA-A), addition of $NaNO_2$, Ca-EDTA and BHA to CA-A(CA-B) and substitution of BHA with sodium citrate in CA-B. The results showed that sodium phosphates and sodium citrate significantly inhibited the kimchi fermentation while potassium phosphate had little effect. The order of control effect was $Na_3PO_4-Na_2HPO_4-sodium\;citrate-NaH_2PO_4-K_2HPO_4-KH_2PO_4$. Among the salts mixtures, CA-A showed the most reducing effect in the fermentation rate followed by CA-C and CA-A. The mixture of CA-C could extend the time of holding pH $4.2{\sim}4.4$ by approximately 6 times at $4{\sim}25^{\circ}C$ when it was compared to control. The microbial growth study of total and Leuconostoc mesenteroides also showed a very significant decrease in their numbers.

• Korean Journal of Food Science and Technology
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• v.18 no.4
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• pp.306-312
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• 1986

Color changes of a mixture of 0.8 M glucose, fructose or sucrose and 0.8 M glycine were evaluated by Hunter 'L', 'a', 'b' values during Maillard reaction at the temperature range of $70^{\circ}-100^{\circ}C$. The results suggested the reaction to be devided into three stages. In initial reaction the 'L' and 'a' values decreased slowely, and 'b' rapidly increased to maximum, which were followed by a rapid decrease in 'L' and 'b' and rapid increase in 'a' values at intermediate stage. At final reaction period the both 'L' and 'b' were slowed down in their reduction rate while 'a' decreased rapidly from its maximum point. All of the Hunter values were reached to nea. zero. Linear equations, which can be used for prediction of cole. change in Maillared reaction, of $1/\sqrt{(L_t-L_{\circ})^2\;+\;(a_t-a_{\circ})^2\;+\;(b_t-b_{\circ})^2}\;=\;a(1/t)\;+\;b$ for Hunter values and $1/\sqrt{X\;+\;Y\;+Z}\;=\;a(1/t)\;+\;b$ for CIE tristimulus values were found to have a very high correlation coefficient. Relationships between 'L' and 'a', 'L' and 'b' and 'a' and 'b' were also graphcally compared.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.123-128
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• 1991

Addition of two different salt mixtures of sodium phosphates, Ca-EDTA, $NaNO_2$ and sodium citrate were investigated for their effects on relative viscosity, textrue, sensory properties of kimchi and solids contents of kimchi and kimchi liquid during fermentation at $4{\sim}3.5^{\circ}C$. The salt mixtures were added into half fermented kimchi with the concentration range of $0.001{\sim}0.01\;M$. The results showed that higher values in viscosity of kimchi liquids were obtained for those fermented at low temperature and with salts mixtures added. The hardness of Chinese cabbage was gernerally increased until pH 4.0 reached and then decreased thereafter for those fermented without salts mixture. However the salts added kimchi showed no decrease and a slightly harder texture measured at the late stage of fermentation. Soluble solids concentration steadly decreased in kimchi liquids for those salts mixture added while those without salts mixture were initially increased followed by slow decrease. Comparison of sensory properties showed that the degree of changes was reduced when salt mixture was added. Higher scores in fresh-sourness and acidic taste, hardness and chewiness in texture and lower moldy odor were obtained when the data was compared for those kimchi having the pH range of $4.0{\sim}4.2$.

• Applied Biological Chemistry
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• v.24 no.1
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• pp.21-28
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• 1981

Brewing method and quality of 15 samples of traditional Kochuzang in Junrabook-do area were investigated. Average combination ratio of glutinous rice: Meju (soybean Koji): red pepper powder was 2 : 0.7 : 1.1. In order to improve the taste of Kochuzang, some amount of natural soysauce was added in the Kochuzang at early stage of fermentation. Average content of sodium chloride was 7.32%; amino nitrogen, 123.3%; total sugar, 31.9%; reducing sugar, 19.4%; ethyl alcohol, 1.13% and the activity of acid protease was 0.07; liquefying amylase, 9.67 and saccharogenic amylase was 15.82. Five samples were selected as excellent Kochuzang through sensory evaluation. These samples were similarly strong in hot and sweet taste with alcoholic flavor, glossy surface and brownish red color.

• Korean Journal of Food Science and Technology
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• v.21 no.6
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• pp.838-844
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• 1989

The physicochemical and organoleptic properties of Korean pickled cucumbers were studies for their changes during fermentation. The Korean pickled cucumbers were prepared by salting in 5-15% NaCl solution and fermented for 7-10 days. The results showed that the increase of salt concentration in cucumber had a linear relationship with logarithmic value of brining time. The higher NaCl concentration in salt solution resulted a rapid salt penetration into cucumber while the rate of changes in pH, the total acidity and turbidity were reduced. The color of cucumber surface were changed from green to yellow-green color as the fermentation progressed. The hardness of cucumber decreased repidly after one day of fermentation, followed by a little decreased until it reached to pH 3.2. A little increase in pH and decrease in total acidity were measured thereafter. The evaluation of sensory quality showed that the acidic and fresh cucumber-like-flayer decreased and yeast-moldy increased as the fermentation progressed. The sensory changes were more evident for lower salt concentration of NaCl solution. The softness of cucumber became to be significant from 4th day of fermentation in 5% salt solution.