• Journal of the Korean Society of Tobacco Science
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• v.3 no.1
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• pp.20-24
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• 1981

This experiment was carried out to determine the relationships between maturity and content of the chemical components in flue-cured tobacco. The results were as follows : 1) Among the chemical components, the contents of total nitrogen, ammonia nitrogen, total alkaloids, nicotine, total volatile base, petroleum-ether extract, crude fiber, crude ash, water soluble ash, and chlorine decreased significantly, and those of total sugar, reducing sugar, and starch increased as leaf maturity progressed until the stage of ripeness, but, afterwards, a reverse tendency appeared. 2) There was a significant relationship between maturity and the contents of chemical components, such as total nitrogen, protein nitrogen, ammonia nitrogen, total volatile base, and the correlation coefficients of them were -0.743, -0.789, -0.797, and -0.642, respectively.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.93-99
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• 2020

A colorimetric paper sensor was used to detect volatile nitrogen-containing compounds emitted from spoiled salmon filets to determine their freshness. The sensing mechanism was based on acid-base reactions between acidic pH-indicating dyes and basic volatile ammonia and amines. A sensing layer was simply fabricated by drop-casting a dye solution of bromocresol green (BCG) on a polyvinylidene fluoride substrate, and its color-change response was enhanced by optimizing the amounts of additive chemicals, such as polyethylene glycol, p-toluene sulfonic acid, and graphene oxide in the dye solution. To avoid the adverse effects of water vapor, both faces of the sensing layer were enclosed by using a polyethylene terephthalate film and a gas-permeable microporous polytetrafluoroethylene sheet, respectively. When exposed to basic gas analytes, the paper-like sensor distinctly exhibited a color change from initially yellow, then to green, and finally to blue due to the deprotonation of BCG via the Brønsted acid-base reaction. The use of ammonia analyte as a test gas confirmed that the sensing performance of the optimized sensor was reversible and excellent (detection time of < 15 min, sensitive naked-eye detection at 0.25 ppm, good selectivity to common volatile organic gases, and good stability against thermal stress). Finally, the coloration intensity of the sensor was quantified as a function of the storage time of the salmon filet at 28℃ to evaluate its usefulness in monitoring of the food freshness with the measurement of the total viable count (TVC) of microorganisms in the food. The TVC value increased from 3.2 × 10⁵ to 3.1 × 10⁹ cfu/g in 28 h and then became stable, whereas the sensor response abruptly changed in the first 8 h and slightly increased thereafter. This result suggests that the colorimetric response could be used as an indicator for evaluating the degree of decay of salmon induced by microorganisms.

• Food Science of Animal Resources
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• v.22 no.2
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• pp.164-171
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• 2002

The purpose of this study was to evaluate inhibitory activity of a bacteriocin mixture from lactic acid bacteria(LAB) against foodborne pathogens. Each bacteriocin solutions were prepared by growing nine strains of bacteriocin producers in MRS broth for 18~24 h followed by centrifugation(8000$\times$g, 20 min, 4$^{\circ}C$). Bacteriocins were purified from ammonium sulfate precipitation and were resuspended in 50 mM phosphate buffer(pH 7.0). Nine bacteriocins were mixed together and then allowed to freeze at -2$0^{\circ}C$. The mixture of nine bacteriocins showed enhanced inhibitory activity compared to each of bacteriocins and inhibited the Gram negative pathogens including Escherichia coli 0157:H7, Klebsiella pneumoniae, Pseudomonas chlororaphis and Shigella sonnei. The mixture of bacteriocin solutions was significantly lower than controls when a freeze-dried bacteriocin mixture was added to frank sausage, Mozzarella cheese and pork loin. With addition of bacteriocin mixture, total mesophilic bacteria in pork loin were constant over storage period, whereas total mesophilic bacteria in Mozzarella cheese and frank sausang slightly increased. Total viable cells of control group increased during storage without bacteriocin treatment. Volatile base nitrogen content of pork loin during storage also increased significantly without bacteriocin treatment. The bacteriocin mixture was capable of inhibiting pathogenic and spoilage microorganisms and extending the shelf-life of cheese and meat products during storage.

• The Journal of Natural Sciences
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• v.7
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• pp.53-58
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• 1995

To elucidate the effect of egg white lysozyme from Ogol fowl on the preservation of milks, fishcurd and sausage, changes of pH, volatile base nitrogen content and viable cell count were investigated during the storage periods at $20^{\circ}C$, $30^{\circ}C$ and $37^{\circ}C$ after the addition of lysozyme in each foods. Volatile base nitrogen count of raw milk as marker of spoilage was lowest(63 mg%) in 0.05% lysozyme addition lot which was stored at $20^{\circ}C$ for 2 days, and its preservation effect by lysozyme at $30^{\circ}C$ was enhanced with addition of glycine(0.1%). Preservation effect by lysozyme in commercial milk at $37^{\circ}C$ and in fishcurd at $5^{\circ}C$ and $20^{\circ}C$ were also good, and when sausage was stored at $5^{\circ}C$ after treatment of lysozyme instead of sorbic acid, its preservation effect was acceptable.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.1
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• pp.102-109
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• 2014

Crab-like flavoring base (CFB) was made from a concentrated snow crab cooker effluent (SCCE) containing five food additives (proline, glycine, arginine, methionine, fructose) using reaction flavor technology (RFT). The volatile flavor compounds in CFB were compared between raw (SCCE) and control (without food additives) samples using solid phase microextraction (SPME) and gas chromatography with mass selective detector. A total of 74 compounds were detected in all samples (30 raw samples, 34 control samples, 55 CFB samples). A total of 22 nitrogen-containing compounds, including 19 pyrazines and 3 pyridines, were formed through RFT and increased 27 times compared to the control. Dimethyl trisulfide and dimethyl disulfide were predominant sulfur-containing compounds that increased through RFT, while aromatic compounds decreased through RFT. Seven compounds, tetramethylpyrazine, 2-ethyl-3,5,6-trimethylpyrazine, 2,3,5-trimethyl-6-(3-methylbutyl)pyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,5-dimethyl-3-(3-methylbutyl)pyrazine, 2-ethyl-3,6-dimethylpyrazine, and 2-decanone potentially have a role in CFB odor by Pearson's correlation analysis.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.3
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• pp.74-99
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• 2022

Surface ozone is produced by photochemical reactions of nitrogen oxides(NOx) and volatile organic compounds(VOCs) emitted from vehicles and industrial sites, adversely affecting vegetation and the human body. In South Korea, ozone is monitored in real-time at stations(i.e., point measurements), but it is difficult to monitor and analyze its continuous spatial distribution. In this study, surface ozone concentrations were interpolated to have a spatial resolution of 1.5km every hour using the stacking ensemble technique, followed by a 5-fold cross-validation. Base models for the stacking ensemble were cokriging, multi-linear regression(MLR), random forest(RF), and support vector regression(SVR), while MLR was used as the meta model, having all base model results as additional input variables. The results showed that the stacking ensemble model yielded the better performance than the individual base models, resulting in an averaged R of 0.76 and RMSE of 0.0065ppm during the study period of 2020. The surface ozone concentration distribution generated by the stacking ensemble model had a wider range with a spatial pattern similar with terrain and urbanization variables, compared to those by the base models. Not only should the proposed model be capable of producing the hourly spatial distribution of ozone, but it should also be highly applicable for calculating the daily maximum 8-hour ozone concentrations.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.3
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• pp.165-171
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• 2020

Maintaining steady and low temperature during distribution process is a key technique to inhibit microbial growth, one of the most important factors in determining the shelf life. It is possible to provide high-quality fresh products to consumers only when precise and adequate temperature control is guaranteed throughout the entire distribution process for fresh seafood. This study investigated the shelf-life of packaged fresh flounder (Paralichthys Olivaceus) in order to learn the feasibility of super-chilled distribution of fresh seafood. To estimate the shelf life, weight, number of bacteria such as E. coli, pH, sensory test and volatile basic nitrogen were investigated. As a result of the study, the difference in shelf life of 6 days at the super-chilling temperature (0±1℃) and 1 day at the general refrigeration temperature (8±2℃) (based on volatile base nitrogen) showed the market possibility of super-chilling distribution. Through additional empirical studies such as packaging methods and economic feasibility, it is expected to promote commercialization of super-chilling containers and packaging system developed in the future and secure customer reliability.

• Journal of the Korean Society of Tobacco Science
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• v.18 no.1
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• pp.49-53
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• 1996

This experiment was carried out to study the effect of oxygen on chemical composition and physical properties of tobacco leaves during flue-curing. The results obtained were as follows: Starch content decreased and sucrose content increased with increasing oxygen supply during curing. Glucose and fructose of the cured leaves showed high content at the 5-10% oxygen supply. Amino-N and nitrate-N increased with increasing oxygen supply. Total nitrogen and NH4-N showed the lowest value at the 5-10% and 10-15% oxygen supply in the cutters and leaf, respectively. Chlorophyll and chlorogenic acid increased, and total volatile base decreased with increasing oxygen supply. The activity of α-amylase increased at the latter period of flue-curing, and the maximum activity point were delayed 12 hours with increasing oxygen supply. Shatter index of cured leaves decreased with increasing oxygen supply. It was desirable to supply oxygen during flue-curing for the improvement of chemical and physical properties such as starch, total sugar, chlorogenic acid, and shatter index of cured leaves.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.68-76
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• 2019

In this study, we propose a squid jeotgal, Korean fermented seafood, supplement with different soy isoflavones supplements, followed by fermentation for different time intervals at $4^{\circ}C$ to increase the antioxidant activity and improve the food value. In the first month, fermented jeotgals with at lowconcentration ($2mg\;g^{-1}$) of added soy isoflavones showed a significant increase in the activity of up to 55%, whereas, at high concentration ($10mg\;g^{-1}$), the activity almost doubled compared to that of the sample without isoflavones. Moreover, the squid enriched with isoflavones also exhibited significantly decreased total volatile base nitrogen, thiobarbituric acid reactive substances, and biogenic amines, indicative of higher inhibition of the formation of these substances. The changes in the microbial profile were also evaluated. This use of soy isoflavanones as an additive could aid in improving the nutritional value of fermented seafood to reduce the incidence of age-related and chronic disorders.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.101-108
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• 2016

We investigated changes in the physiochemical quality of sailfin sandfish sauces fermented with two kojis during long-term storage at room temperature. Four fish sauces, including a control, were prepared by salt-fermentation with soybean koji (S-koji) or rice koji (R-koji) after autolysis. During storage, for 12 months, the color and levels of amino acids, total volatile base nitrogen (T-VBN) and organic acids but not moisture, salt or total nitrogen levels or pH differed markedly according to fish sauce type. The total nitrogen level was highest in S-koji, but there was no difference in the rate of increase in amino acid levels among the four fish sauces during storage. The T-VBN, of autolysis and S-koji were significantly higher than those of the control and R-koji during the entire storage period (P<0.05). The initial organic acid level did not differ among the four fish sauces, whereas it was notably higher in R-koji than in the other sauces at the end of storage. Hunter L, a and b values decreased in all fish sauces with increasing storage time. In conclusion, soybean koji may enhance the levels of nitrogen compounds as well as T-VBN in fish sauce, while rice koji reduced the formation of excess T-VBN and increased organic acid levels during storage at room temperature.