• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.576-580
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• 1997

Lipoxygenase activity in Chinese cabbage was measured at various concentrations of brines. Lipoxygenase activity on linoleic acid substrate was determined by changing the rate of dissolved oxygen consumption. The inactivation of lipoxygenase by salting was increased when concentration of sodium chloride and soaking time were increased. About 60% of enzyme activity was reduced after submerging in 13% brine solution for 5 hr. The addition of calcium chloride (0.7%) reduced about $10{\sim}15%$ of lipoxygenase activity rather than without. Residual activity of lipoxygenase in Chinese cabbage submerged in 13% brine was 20% and about 60% of lipoxygenase was also inhibited by addition of garlic extract.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.808-812
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• 1998

Melania snail(Semisulcopira bensoni) is used as ingredient in Korean traditional soup and nutritional foods. Generally, lipoxygenase in several food products may produce off-flavors during their processing and storage. Therefore, the inactivation of lipoxygenase is required to make the better extracts from Melania sanil. Also, the quality on freshness of Melania snail may be evaluated by lipoxygenase activity. The lipoxygenae activity was the highest at 40~60% saturation among several concentrations in salting-ouot saturated solution of ammonium sulfate. The partial purification of lipoxygenase was successfully obtained by Sephacryl S-200 gel chromatography. The first peak among three peaks for protein determination showed the highest activity of lipoxygenase in 13~16 fractions among 100 fractions. The highest peak of lipoxygenase activity by ion exchange chromatography was shown at 0.1M NaCl. In the purification step, the specific activity was 20.8U/mg and activity yield was 19.8%. The optimum pH and temperature were pH6.0~8.0 and 3$0^{\circ}C$, respectively. Molecular weight of the lipoxygenase was estimated about 35kDa by SDS-PAGE.

• Korean Journal of Food Science and Technology
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• v.13 no.1
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• pp.53-56
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• 1981

Several tests were conducted to study lipoxygenase activity and off-flavor developement in frozen sweet corn. Fresh corn contained about 60% of total lipoxygenase activity in the germ section. When non-blanched frozen sweet corn was stored at $-10^{\circ}F$, it developed off-flavor and most significant changes in the flavor profile of off-flavored sweet corn was $4{\sim}5$ times higher hexanal peaks. The high hexanal peaks observed in the sterilized sweet corn with added lipoxygenase, alone and in combination with other enzymes, suggested the fact that high hexanal peaks in off-flavored sweet corn could be due to an oxidative reaction of lionleic acid (and other unsaturated fatty acids) catalyzed by lipoxygenase. Based on lipoxygenase activity and linoleic acid content in sweet corn, this reaction occur most heavily in the germ section of sweet corn. There was a significant relationship between flavor score of frozen stored corn-on-the-cob and hexanal peak in the germ section of corn-on-the-cob. This result indicated that hexanal peak could be used as an objective index of off-flavor development in frozen sweet corn.

• Korean Journal of Food Science and Technology
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• v.27 no.3
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• pp.290-293
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• 1995

This study was designed to investigate the effect of potato lipoxygenase on the change of dough chemical composition including lipid distribution, fatty acid composition, carotenoids content and color value in wheat flour dough. For the study, the potato lipoxygenase was added to wheat flour at a level of $6.5{\times}10\;unit/g$ flour. The addition of potato lipoxygenase to wheat flour dough was found to cause an increase in free lipid content, an effect apparently related to the decrease in linoleic acid content and increase in peroxide value. This phenomena might be due to the enzymatic oxidation of polyunsaturated fatty acid. Also, the bleaching effect of lipoxygenase was observed as the decrease in carotenoids content of wheat flour dough. In comparison of color value, it was shown that redness, yellowness and total color difference$({\delta}E)$ were lower by addition of lipoxygenase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.123-126
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• 2002

Lipoxygenase might be associated with seed deterioration by catalyzing the incorporation of molecular oxygen into fatty acids and generating free radicals. This study was performed to determine whether seed lipoxygenase activity would alter soybean seed longevity. In this study, germination percentage of lipoxygenase-lacking cultivar Jinpumkong2 (lx1lx1lx2lx2lx3lx3) was lower than that of Taekwangkong (Lx1Lx1Lx2Lx2Lx3Lx3). Segregation ratio for the three lipoxygenase isozymes of the F2-derived from the cross between Taekwangkong and Jinpumkong2 was fitted to 9 (Lx1Lx2Lx3) : 3 (Lx1Lx2lx3) : 3 (lxllx2Lx3) : 1 (lx1lx2lx3), suggesting the tight linkage between the Lx1 and Lx2 loci. Germination percentages varied widely but not differed among lipoxygenase isozyme types of F$_3$ seeds before and after accelerated aging. Seed coat of Jinpumkong2 was damaged severely following accelerated aging, whereas that of Taekwangkong was not. Thus, seed of lipoxygenase-lacking soybean cultivar, Jinpumkong2 showed greater deterioration compared with that of the normal Taekwangkong. However, the presence or absence of lipoxygenase activity had no effect on soybean germination.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.29-35
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• 2007

This study was conducted to investigate the germination rate, fat acidity and lipoxygenase activity of brown rice after storage of 6 and 12 weeks at high temperature ($35^{\circ}C$) with fifteen Korean and two Japanese rice varieties. Germination rate in rough rice and palatability value in cooked rice by rice taster were lower with longer storage period, while protein content, fat acidity, and lipoxygenase activity in brown rice were higher with longer storage period. Fat acidify was negatively correlated with germination rate. However fat acidity was positively correlated with lipoxygenase activity. Seventeen varieties were classified into two groups on the basis of germination rate, fat acidity and lipoxygenase activity after 12 weeks' storage at high temperature; Group I including eleven varieties of Odaebyeo, Sangmibyeo, Unkwangbyeo, Ilpumbyeo, Nampyeongbyeo, Ilmibyeo, Donganbyeo, Jungsanbyeo, Koshihikari, Hitomebore and Chucheongbyeo showed high germination rate, low fat acidity and low lipoxygenase activity, while Group II including six varieties of Sindongjinbyeo, Hoanbyeo, Gyehwabyeo, Daeyabyeo, Hopyeongbyeo, and Dongin 1 showed lower germination rate, high fat acidity and high lipoxygenase activity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.739-747
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• 1997

This study was performed to clarify various conditions on the test of lipoxygenase-l and to establish the application of new test method for varietal improvement of soybeans in order to decrease beany flavors. Potassium borate and Tris were used as buffer and O.1M potassium borate solution showed the best result for the lipoxygenase-l test. In the range of pH 8.5~9.0 of the buffer, 2mM linoleic acid as substrate was effective. For color development, 100$\mu$l of two solutions(KI and starch) were added to the half soybean seed, successively. The substrate solution included linoleic acid was stored safely for 10 days at 4$^{\circ}C$ in refrigerator and for 4 days at room temperature. The best result was as follows; the 1ml of substrate solution[0.1M potassium borate(pH 9.0), 0.1％ Tween-20, 2mM linoleic acid] was added to the chipped half soybean seed in l.5ml plastic tube, waited for 15 minutes, and 100$\mu$l of color development solutions(5％ saturated KI in 15％ acetic acid, 1％ starch) were added to the tube, successively. After 4 hours, the purple color was observed in the upper phase of the plastic tube in the presence of lipoxygenase-1 and milky color in absence of lipoxygenase-1. The purple color was stable from 4 to 24 hours. There was no interfering effect by lipoxygenase-2 and -3. The plastic tube should be placed in the tube stand without shaking during the lipoxygenase-l test.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.314-319
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• 1997

The objectives of this study were to examine the effect of storage time, temperature, pH, and NaCl concentration on hydroperoxide lyase and lipoxygenase activities, and to establish important informations to the production of typical cucumber flavor. Conditions affecting lipoxygenase and hydroperoxide lyase would be important for cucumber flavor production. Maximum activity was observed at pH 5.0 for hydroperoxide lyase and pH 5.5 for lipoxygenase. Both enzymes were relatively stable at $40\;to\;50^{\circ}C$ for 6days storage time. Maximum activity of both enzymes was observed with 0.2 M NaCl at pH 5.0. Activities were stimulated with concentrations of NaCl from 0.05 to 0.2 M. Hydroperoxide lyase and lipoxygenase activities were decreased at concentration of NaCl greater than 0.2 M.

• BMB Reports
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• v.33 no.2
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• pp.172-178
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• 2000

The lipoxygenase was purified 35 fold to homogeneity from the Korean red potato by an ammonium sulfate precipitation and DEAE-cellulose column chromatography. The simple purification method is useful for the preparation of pure lipoxygenase. The molecular weight of the enzyme was estimated to be 38,000 by SDS-polyacrylamide gel electrophoreses and Sepharose 6B column chromatography. The purified enzyme with 2 M $(NH_4)_2SO_4$ in a potassium phosphate buffer, pH 7.0, was very stable for 5 months at $-20^{\circ}C$. Because the purified lipoxygenase is very stable, it could be useful for the screening of a lipoxygenase inhibitor. The optimal pH and temperature for lipoxygenase purified from the red potato were found to be pH 9.0. and $30^{\circ}C$, respectively. The Km and Vmax values for linoleic acid of the lipoxygenase purified from the red potato were $48\;{\mu}M$ and $0.03\;{\mu}M$ per minute per milligram of protein, respectively. The enzyme was insensitive to the metal chelating agents tested (2 mM KCN, 1 and 10mM EDTA, and 1 mM $NaN_3$), but was inhibited by several divalent cations, such as $Cu^{++}$, $Co^{++}$ and $Ni^{++}$. The essential amino acids that were involved in the catalytic mechanism of the 5-lipoxygenase from the Korean red potato were determined by chemical modification studies. The catalytic activity of lipoxygenase from the red potato was seriously reduced after treatment with a diethylpyrocarbonate (DEPC) modifying histidine residue and Woodward's reagent (WRK) modifying aspartic/glutamic acid. The inactivation reaction of DEPC (WRK) processed in the form of pseudo-first-order kinetics. The double-logarithmic plot of the observed pseudo-first-order rate constant against the modifier concentration yielded a reaction order 2, indicating that two histidine residues (carboxylic acids) were essential for the lipoxygenase activity from the red potato. The linoleic acid protected the enzyme against inactivation by DEPC(WRK), revealing that histidine and carboxylic amino acids residues were present at the substrate binding site of the enzyme molecules.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.6
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• pp.833-838
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• 1993

A strain of Penicillium sp. extracellularly produced an inhibitory substance for lipoxygenase. These purification procedures were followed : ethanol treatment, chromatographies on Dowex 50W, Sephadex G-25, silica gel column and HPLC. The inhibitor was stable in pH range from 3.0 to 5.0 at $25^{\circ}C$, and a treatment at 10$0^{\circ}C$ for 2 hours didn't diminish its original activity. The purified inhibitor was charred at temperature near 22$0^{\circ}C$~23$0^{\circ}C$ and decomposed. Molecular weight of the inhibitor was estimated to be approximately 270 by Sephadex G-25 column chromatography. The inhibitor rapidly formed EI complex with lipoxygenase and inhibited enzyme activity.