• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1135-1139
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• 1997

Major factors inhibiting nonenzymatic browning in stored ginger paste were investigated using aqueous model systems with temperature, water activity, pH and sulfur compounds. Browning index and total gingerols were measured during storage. The rate of nonenzymatic browning reactions showed a strong depencence on temperature and pH and a negligible influence on water activity. It was also reduced by the addition of 0.04% N-actyl-L-cysteine(NAcCys), effectively. Activation energies for aqueous ginger model systems with and without 0.04% NAcCys were 29.0 and 25.8kcal/mole, respectively.

• Toxicological Research
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• v.13 no.3
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• pp.223-228
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• 1997

Quinones have been reported to undergo nonenzymatic reaction with thiols to generate reactive oxygens. It is therefore possible that the nonenzymatic reaction of quinones with thiols in plasma could lead to potentJared cellular toxicity or disease. When 1 mM menadione was added in plasma under pH 11.2, 7.4 and 5.0, the increase in oxygen consumption rate was the order of pH 11.2 > pH 7.4 > pH 5.0. In addition, oxygen consumption rates under plasma anticoagulated with trisodium citrate solution (pH 7.85) was significantly higher than those with acid-citrate-dextrose solution (pH 6.87). SOD and catalase reduced the rate of oxygen consumption induced by menadione in plasma. Taken together, these results suggest that the menadione-induced increased oxygen consumption was due to nonenzymatic reaction of menadione with thiols in the plasma. The presence of plasma has an additive effect on the increased oxygen consumption rates induced by the menadione treatments on our model tissue, platelets, as compared between washed platelet (WP) and platelet rich plasma (PRP). Cytotoxicity, as determined by LDH release, are well correlated with the oxygen consumption rates observed in each system and strongly suggest that menadione-induced cytotoxicity can be increased with the presence of blood plasma.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.305-309
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• 1998

The superoxide dismutase (SOD) activity of seven Bifidobacterium spp. strains was examined by an indirect SOD assay method. Some Bifidobacterium spp. showed significant levels of SOD activity. However, we could not observe any significant differences between anaerobic and aerobic cultures. Furthermore, although several Bifidobacterium spp. exhibited some degree of tolerance to paraquat which produces superoxide radicals, the apparent SOD activity of these strains was not correlated with their resistance to paraquat. In addition, when we added increasing amounts of manganese or iron to MRS medium which had been prepared without either of the metal ions, the apparent SOD activity of cell free extracts (CFEs) was increased with increasing concentration of both metal ions. To our surprise, the heat-denatured CFEs also showed nearly identical correlative patterns. Based on these results, the apparent SOD activity was likely due to a nonenzymatic dismutation. These results strongly suggest that high concentration of divalent metal ions ($Mn^{2+}$, $Fe^{2+}$) in MRS medium result in nonenzymatic dismutation which can lead to false positive SOD activities in Bifidobacerium spp.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.433-439
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• 1996

Major components affecting nonenzymatic browning in stored ginger paste were investigated using five synthetic model solutions.　The model systems were stored at $40^{\circ}C$ for 30 days and analyzed for browning, in addition the contents of sugars, organic acids, ascorbic acids, amino acids and gingerols were determined. Among the chemical components, fructose, asparagine and ascorbic acid were the main contributors to the browning development of ginger paste, while gingerol compounds were browning inhibitors.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.721-722
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• 2013

• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.425-429
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• 1989

Functional relationships of carotenoid destruction and nonenzymatic browning during red pepper drying were established by the dynamic test using the moisture-temperature-quality history curve in actual drying experiments. The dependence of the rate constants on temperature and moisture content was established and analysed assuming that carotenoid destruction and nonenzymatic browning are the first order and the zero order reaction, respectively. Carotenoid destruction rate constant was high at high moisture and high temperature, and had a minimum value at some intermediate moisture content. As dependence of rate constant on temperature, activation energy of carotenoid decolorization ranged from 7.7 to 27.4 kcal/mol, showing higher value at higher moisture content. Nonenzymatic browning showed higher rate at higher temperature and higher moisture content. Activation energy of browning was in the range of 7.5-20.2 kcal/mol with higher value at higher moisture level.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.147-153
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• 2008

Improvement of the selectivity of nonenzymatic glucose based on mesoporous platinum ($H_1$-ePt) by using A.C. impedance is reported. The idea of the present work is based on the novel effect of the mesoporous electrode that the apparent exchange current due to glucose oxidation remarkably grows although the reaction kinetics on the surface is still sluggish. It is expected that the enlarged apparent exchange current on the mesoporous electrode can raise the sensitivity of admittance in A.C. impedance to glucose concentration. At a low frequency, A.C. impedance could become more powerful. The admittance at 0.01 Hz is even more sensitive to glucose than to ascorbic acid while amperometry exhibits the inverse order of sensitivity. This is the unique behavior that is neither observed by A.C. impedance on flat platinum electrode nor obtained by amperometry. The study shows how the combination of A.C. impedance and nano-structured surface can be applied to the detection of sluggish reaction such as electrochemical oxidation of glucose.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.3
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• pp.169-176
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• 1988

In order to obtain the objective indices which can assess the quality and the shelf-life of dried squid, nonenzymatic browning, carbonyl value, trimethyl amine (TMA) and trimethyl amine oxide (TMAO) decrease and panel test were determined in dried squid at various water activity levels. When the data of nonenzymatic browning fit a zero order equation, $r^2$ value were more than 0.92 except aw 0.52 for 0.8241. Through variance analysis for the data of browning extent and TMAO decrease, the confidence limits of regression equation were $99\%$ and their limit values of shelf-life were shown 0.45390 O. D./g. solid and 190.322 g/g respectively. In case of TMAO, $r^2$ value was calculated more than 0.95. Linear regression equation for the correlation between browning data and average panel score was Y=0.6138-0.053X and its $r^2$ value was 0.9285. Also in TMAO decrease, the equation was InY=2.0314+0.08269x and $r^2$ value was 0.7854. The shelf-life, evaluated by nonenzymatic browning, TMAO decrease and panel test, was 110-170 days at aw 0.45-0.76 except aw 0.15.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1140-1146
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• 1997

Storage stability of ginger paste product was investigated from the standpoint of the inhibition of nonenzymatic browning and loss of gingerol contents. For the experimentations, control, 0.04% of N-acetyl-L-cysteine in ginger paste(NAcCys), and combination treatment of NAcCys, 0.92 of water activity and 6.30 of pH in ginger paste (mixed treatment) were stored at 3$0^{\circ}C$ for 40 days and analyzed for browning and gingerol contents. In addition the changes in sugars, organic acids, ascorbic acids, amino acids, and sensory quality were determined. The results revealed that the mixed treatment agent was effective in preventing both nonenzymatic browning and loss of gingerol contents. The inhibition by combination treatment might be resulted from the control of radical formations by sulfhydryl groups of NAcCys and the increase of diffusion resistance in lower water activity. Browning development and total gingerol contents were found to be correlated to some physicochemical characteristics of ginger paste; that is, browning development to amino acid and color value in sensory evaluation, and total gingerol contents to flavor in sensory evaluation.

• The Korean Journal of Food And Nutrition
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• v.32 no.5
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• pp.417-424
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• 2019

The purpose of this study was to observe the effects of the polysaccharide (GLP) obtained from the liquid cultured Ganoderma lucidum on the lipidperoxidation in a rat liver microsome and hepatotoxicity in the primary cultured rat hepatocytes. It is well known that the polysaccharide of Ganoderma lucidum exhibits hepatoprotective activity, antitumor activity etc., which many suggest a relationship to lipidperoxidation. The effect of GLP on $CCl_4-$ and galactosamineintoxicated cytotoxicity in the primary cultured rat hepatocytes were reduced the GPT value. In order to the estimate the effects of anti-lipidperoxidation of the polysaccharide, enzymatic and nonenzymatic reaction assays were performed, in vitro, in the rat liver microsome. An enzymatic lipidperoxidation reaction by $ADP+FeCl_3+NADPH$ and $CCl_4+NADPH$, GLP (1 mg/mL) inhibited 77.4% and 39.4%, respectively, and the nonenzymatic reaction displayed a 97.4% strongly inhibition. In the enzymatic and nonenzymatic inducers treated with GLP, the formation of malondialdehyde (MDA) progressively decreased by raising the GLP concentration. These results suggest that the anti-lipidperoxidation and radical scavenging activity of GLP may play an important part in the liver protection action.