• Food Science and Biotechnology
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• v.18 no.3
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• pp.732-738
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• 2009

An acidic polygalacturonase (PG) from Aspergillus kawachii was produced by solid state fermentation employing a polyurethane foam support. The conditions used for the production of acidic PG were particle size of support (0.6 or 500 $mm^3$) and fermentation time. From the factors studied, the particle size had important influence on enzyme production. The best conditions for acidic PG production were $0.6\;mm^3$ particle size, 18 hr at $30^{\circ}C$ and initial pH of 5.0. In addition, pectin was extracted from citrus pomaces (grapefruit, lime, and tangerine) by acidic PG at $50^{\circ}C$ for 24 hr with citric acid solution. Infrared spectroscopy showed that lime pomace had more high-methoxylated (65%) endogenous pectin than was obtained than from grapefruit or tangerine pomaces. The enzymatically extracted pectin yield in dry basis (d.b.) for grapefruit and lime pectins were 6.95 and 4.25%, respectively. The citric acid solution alone also contributed to pectin extraction from citrus pomaces (7-9%, d.b.). Limited pectin extraction by acidic PG from tangerine pomace was most likely due to the presence of low-methoxylated endogenous pectin. The enzymatic method for pectin extraction using acidic PG from A. kawachii is a promising technique for releasing highly polymerized pectic substances from high-methoxylated lime or grapefruit pomaces.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.132-138
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• 1998

This study was conducted to evaluate the storage stability of danmooji(salted radish) treated with high hydrostatic pressure $(300{\sim}686\;MPa)\;and\;heat\;(55^{\circ}C)$. Danmooji pressurized at 500 MPa and 686 MPa for 5 min showed $4{\sim}6log-cycle$ reductions in total microorganism, while danmooji heated at $55^{\circ}C\;for\;2\;hr\;showed\;3{\sim}5log-cycle$ reductions. However, danmooji pressurized at 300 MPa for 5 min showed a 2 log-cycle reduction, indicating that pressurization at lower than 300 MPa is insufficient for sterilization. After pressurized at 300 MPa, 500 MPa and 686 MPa for 5 min, pectinesterase (PE) activity of danmooji was increased by approximately 35%, 76% and 64%, respectively; and polygalacturonase (PG) activity of danmooji was increased by 109%. 163% and 120%, respectively. After heated at $55^{\circ}C$ for 2 hr, PE and PG activities of danmooji were increased by 18% and 200%, respectively. This indicates that PE in danmooji was more activated bypressure than heat, while PG was mostly activated by heat. Pressurized and heat-treated danmooji had higher hardness than control and maintained its hardness during storage at $30^{\circ}C$.

• Food Science and Preservation
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• v.16 no.6
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• pp.804-809
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• 2009

Recently, many Koreans have started to consume aged kimchi fermented long-term at low temperatures. In the present study, the effect of low temperature ($5^{\circ}C$) on pH, titratable acidity (TA), organic acid level, viable microbial cell count, amino acid concentration, and polygalacturonase activity (PG) during long-term fermentation (46 weeks) of kimchi, were evaluated. After 10 weeks of fermentation, kimchi had a pH of 4.1 and a TA of 1.0%, respectively after 46 weeks fermentation, these values were 3.9 and 1.3%, respectively. Lactic acid, the ratio of lactic acid to acetic acid, and the ratio of Lactobacillus species/Leuconostoc species in kimchi increased as fermentation progressed from 10 weeks to 46 weeks. However, total viable cell counts of aerobic bacteria, yeasts, Lactobacillus species, and Leuconostoc species, free amino acid levels, and PG decreased as the fermentation period was extended from 10 weeks to 46 weeks.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.149-153
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• 1989

Polygalacturonase(PG) and pectinesterase(PE) were extracted from Chinese cabbage and physicochemical properties of the enzymes were characterized. The preheating conditions for maximum retention of Kimchi texture were also studied. The activity of PE was highest at $50^{\circ}C$ and at 0.02M $CaCl_2$ but decreased in 0.2M $CaCl_2$, PG exhibited maximum activity at $65^{\circ}C$ with 0.3mM $CaCl_2$ but was inhibited by $CaCl_2$ at 0.5mM. Both of the enzymes, however, exhibited the maximum activity with 0.25M NaCl. Optimum preheating treatment was determined for minimum PG activity and maximum PE activity. Thus a maximum crispness and firmness was obtained with preheating in 0.05M $CaCl_2$ solution at $50^{\circ}C$ for 1.5hr results indicated that PE activity and calcium ion were very effective in preserving firmness.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.596-601
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• 1998

Effects of high hydrostatic pressure on microorganisms, pectin enzymes and texture of dongchimi (pickled radish roots) were investigated. Dongchimi was pressurized at $200{\sim}686\;MPa$ for 5 min when its pH reached to 4.0. Total aerobes, initial concentration of $4.05{\times}10^8\;CFU/mL$, were completely inactivated by high hydrostatic pressure at 600 MPa. Lactic acid bacteria, yeasts and molds, initial concentration of $3.25{\times}10^8\;CFU/mL\;and\;3.55{\times}10^4\;CFU/mL$, respectively, were completely inactivated by high hydrostatic pressure at 400 MPa. Leuconostoc mesenteroides appeared to be the most barotolerant lactic acid bacteria because it was the sole bacteria survived at 380 MPa. Pectinesterase (PE) and polygalacturonase (PG) activities increased after high hydrostatic pressure treatment. Residual PE activity was 193 after pressurization at 500 MPa, and residual PG activity was 191 after pressurization at 686 MPa when the initial enzyme activity of control was set to 100. The hardness of pressurized dongchimi was higher than control.

• Korean Journal Plant Pathology
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• v.13 no.4
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• pp.225-231
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• 1997

Activities of polygalacturonase, laccase, and intra- and extra-cellular $\beta$-glucosidase produced by 20 Botrytis cinerea isolates in liquid culture media containing cucumber cell was as a carbon source were measured and their relationships to the pathogenicity were analyzed. No significant correlations between these enzyme activities and the pathogenicity of B. cinerea were found. Mycelial growth rate on Bayendamm media, however, was higthly correlated with the pathogenicity (r=0.522) anong these isolates. Immuno-blot analysis of the culture filtrate using antibody against against exo-polygalacturonase revealed that only one band with molecular weight of 66 kDa was detected amone 34 tested isolates. It appears that these enzymes may not be primary factors in dermining the pathogenicity of B. cinerea.

• The Korean Journal of Mycology
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• v.18 no.1
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• pp.7-12
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• 1990

Isolates of Penicillium expansum with reduced pathogenicity were arbitrarily selected among benomyl-resistant isolates in order to investigate relationship of their pectolytic enzyme acitivity with pathogenicity. In artificial medium, strongly pathogenic isolate $S_1$ and weakly pathogenic isolate $R_2$ produced considerable amonts of endo-polymethylgalacturonase, endo-polygalacturonase, pectin methyl-trans-eliminase, and polygalacturonate-trans-eliminase. No marked difference in enzyme activities was observed between two isolates. In apple medium, the activities of endo-polymethylgalacturonase and endo-polygalacturonase of isolate $S_1$ were over 6 times higher than those of isolate $R_2$. But pectin methyl-trans-eliminase and polygalacturonate-trans-­eliminase did not show a great difference. Activities of endo-polymethylgalacturonase and endo­polygalacturonase precipitated at 80-95% saturation of ammonium sulfate were highest, and addition of these enzyme solutions increased pathogenicity of weakly pathogenic isolates $R_{1-4}$.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.332-337
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• 2003

Enzyme kinetics data play a vital role in the design of reactors and control of processes. In the present study, kinetic studies on pectinases were carried out. Partially purified polymethylgalacturonase (PMG) and polygalacturonase (PG) were the two pectinases studied. The plot of initial rate vs. initial substrate concentration did not follow the conventional Michaelis-Menten kinetics, but substrate inhibition was observed. For PMG, maximum rate was attained at an initial pectin concentration of 3 g/l, whereas maximum rate was attained when the initial substrate concentration of 2.5 g/l of polygalacturonic acid for PG I and PG II. The kinetic data were fitted to five different kinetic models to explain the substrate inhibition effect. Among the five models tested, the combined mechanism of protective diffusion limitation of both high and inhibitory substrate concentrations (semi-empirical model) explained the inhibition data with 96-99% confidence interval.

• Korean journal of food and cookery science
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• v.7 no.4
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• pp.1-7
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• 1991

The object of this study was to investigate the enzyme system in kimchi during fermentation. The results were as follows; 1. Pectinesterase (PE) activity initially increased, following a decrease in kimchi juice but progressively decreased in kimchi solid. 2. Polygalacturonase(PG) activity in kimchi juice initially increased following a decrease near to absence and then increased again. PG activity in kimchi solid, initially decreased following a increase. 3. Peroxidase (POD) activity in kimchi juice initially increased, following a decrease and that in kimchi solid progressively decreased. 4. The activity of ascorbic acid oxidase(AAO) in kimchi juice slightly decreased, following a increase but decreased again. The activity of AAO in kimchi solid, progressively decreased. The cause for the slight increase of the activities of enzymes in kimchi juice after kimchi making was thought to be the extracting effects from kimchi solid. The disappearance of all enzyme activities in fermentation was due to the decrease of pH and the inactivation of enzymes owing to prolongation of fermentation. The cause of increase of PG activity in late fermentation, may be the proliferation of aerobic organisms.

• Journal of the Korean Home Economics Association
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• v.34 no.4
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• pp.403-414
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• 1996

The softening of the femented vegetables and the fruits was resulted from the degradation of pectin substances, cellulose, hemicellulose by polygalacturonase(PG), pectinesterase(PE), Cx-cellulase, $\beta$-galctosidase. The conversion of insoluble pectin to soluble pectin in cell wall-middle lamella was a major factor in the changes of firmness. Ca2+ was substantially increased firmness. However, Ca2+ could be removed from cell wall by chelating agents such as oxalic acid and citric acid. And Ca2+ was replaced with Na+ by ion exchange reaction. Ca2+ deficient tissue was vulnerable to attack by PG. Preheating treatment and Ca2+ addition is most effective in inhibiting the vegetable food softening and in increasing middle lamella-cell wall regidity, which PE activation by preheating treatment and Ca2+ addition could created more anionic carboxyl groups for cationic materials binding such as Ca2+ and chitosan and for polypectategel formation. Excessive demethylation by PE was associated with loosening of middle lamella cell wall components and softening.