• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1784-1791
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• 2016

Garlic was subjected to eight different cooking methods (raw, boiling, steaming, microwave cooking, deep-frying, oven-roasting, pan-frying, and pan-roasting) utilized for typical Korean cuisine. Garlic was analyzed for antioxidant activities and physicochemical properties to elucidate effects of cooking. Garlic cooked at higher temperatures showed significantly lower lightness and higher yellowness (P<0.001). In particular, deep-frying and pan-frying resulted in lowest lightness and soluble solid content, indicating that non-enzymatic browning reactions were more facilitated. Compared with raw garlic, all cooked garlic tended to have lower thiosulfinates, presumably due to decomposition into polysulfides and/or leaching into cooking water and oil. Microwave cooking retained organic acids, total reducing capacity, and flavonoids, which can be attributed to low microwave intensity and shorter cooking time under which heat-labile bioactive components might have undergone less decomposition. Cooking significantly increased metal-chelating activity (P<0.001). In addition, oven-roasting and pan-roasting enhanced total reducing capacity and flavonoid content, indicating that thermal treatments increased the extractability of bioactive components from garlic. However, boiling, deep-frying, and pan-frying, in which garlic is in contact directly with a hot cooking medium, reduced antioxidant activities. Deep-frying resulted in largest reduction in DPPH radical scavenging activity of garlic, which correlated well with reduction of total reducing capacity and flavonoid content. The results show that the antioxidant activity of garlic could be affected by cooking method, particularly heat intensity and/or direct contact of the cooking medium.

• Journal of Mushroom
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• v.16 no.2
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• pp.74-78
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• 2018

This study was carried out to establish a suitable method for liquid spawn production from Lentinula edodes. The optimum production of liquid spawn (OLS) was achieved using soybean meal medium (SMM) with 0.3% of 850 um oak powder and 10-day incubation period and 0.6 vvm aeration volume. OLS showed activities of laccase on ABTS agar plate and carboxymethyl cellulase (CM-cellulase) on CMC agar plate. In case of liquid spawn, fruiting-body development period was delayed approximately 1 day compared to that of sawdust spawn, however, the yield of 153 g per 1.2 kg polypropylene bag was similar to that of sawdust spawn.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.73-79
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• 2010

The Korea Polar Research Institute (KOPRI) has assembled a culture collection of cold-adapted bacterial strains from both the Arctic and Antarctic. To identify excellent protease-producers among the proteolytic bacterial collection (874 strains), 78 strains were selected in advance according to their relative activities and were subsequently re-examined for their extracellular protease activity on $0.1{\times}$ ZoBell plates supplemented with 1% skim milk at various temperatures. This rapid and direct screening method permitted the selection of a small group of 15 cold-adapted bacterial strains, belonging to either the genus Pseudoalteromonas (13 strains) or Flavobacterium (2 strains), that showed proteolytic activities at temperatures ranging between $5-15^{\circ}C$. The cold-active proteases from these strains were classified into four categories (serine protease, aspartic protease, cysteine protease, and metalloprotease) according to the extent of enzymatic inhibition by a class-specific protease inhibitor. Since highly active and/or cold-adapted proteases have the potential for industrial or commercial enzyme development, the protease-producing bacteria selected in this work will be studied as a valuable natural source of new proteases. Our results also highlight the relevance of the Antarctic for the isolation of protease-producing bacteria active at low temperatures.

• Research in Plant Disease
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• v.18 no.3
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• pp.186-193
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• 2012

Biotransformation is an eco-friendly and efficient method for enhancing the bioavailability of biopesticide. To increase the antifungal activity of the crude extract of Cynanchum wilfordii roots against barely powdery mildew, we performed biotransformation of wilfoside C1G using ${\beta}$-glucosidase (cellobiase from Aspergillus niger). The mixture (G sample) of partially purified wilfoside C1G and cynauricuoside A (K1G) was treated with ${\beta}$-glucosidase to remove a glucopyranosyl moiety. The enzyme completely converted C1G to C1N and K1G to K1N. Optimal conditions for enzymatic biotransformation of G sample were determined to be 10% ethanol, 1,555 ${\mu}U$ ${\beta}$-glucosidase/ml, pH 5, and $45^{\circ}C$. In in vivo experiment, the G sample transformed by ${\beta}$-glucosidase showed stronger antifungal activity against barley powdery mildew than the non-treated G sample. These results suggest that ${\beta}$-glucosidase biotransformation can be applied to increase the antifungal activity of the crude extract of C. wilfordii roots against powdery mildews.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.504-511
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• 2016

Lactulose, a synthetic disaccharide, has received increasing interest because of its role as a prebiotic that can increase the proliferation of Bifidobacterium and Lactobacillus spp. and enhance the absorption of calcium and magnesium. While the industrial production of lactulose is still mainly achieved by the chemical isomerization of lactose in alkaline media, this process has drawbacks including the need to remove catalysts and by-products, as well as high energy requirements. Recently, the use of cellobiose 2-epimerase (CE) has been considered an interesting alternative for industrial lactulose production. In this study, to develop a process for enzymatic lactulose production using CE, we screened improved mutant enzymes ($CS-H^RC^E$) from a library generated by an error-prone PCR technique. The thermostability of one mutant was enhanced, conferring stability up to $75^{\circ}C$, and its lactulose conversion yield was increased by 1.3-fold compared with that of wild-type CE. Using a recombinant Escherichia coli strain harboring a CS35 $H^RC^E$-expressing plasmid, we prepared cell beads immobilized on a Ca-alginate substrate and optimized their reaction conditions. In a batch reaction with 200 g/l lactose solution and the immobilized cell beads, lactose was converted into lactulose with a conversion yield of 43% in 2 h. In a repeated 38-plex batch reaction, the immobilized cell beads were relatively stable, and 80% of the original enzyme activity was retained after 4 cycles. In conclusion, we developed a reasonable method for lactulose production by immobilizing cells expressing thermostable CE. Further development is required to apply this approach at an industrial scale.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.451-455
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• 1994

To detect naturally occurring bioactive compounds from unused marine resources, the screening for the 5-lipoxygenase(potato lipoxygenase-II) inhibitors in Asterina pectinifera, Halocynthia roretzi skin, Nototodarus sloani ink, Anthocidaris crassispina skin, Sargassum horneri, Agarum cribrosum, Odonthalia corymbifera and Desmarestia ligulata was carried out. Water, ether, acetone and methanol fractions extracted from Sargassum horneri had strong inhibitory effect on enzymatic lipid oxidation by potato lipoxygenase-II, and their $IC_{50}$ were 320, 18, 9.5 and $100\;{\mu}g/mL$, respectively. The $IC_{50}$ of ether fraction extracted from Asterina pectinifera and acetone fraction extracted from Nototodarus sloani ink were 29.5 and $34.3\;{\mu}g/mL$, and these extracts showed relatively excellent inhibitory activity. Nonpolar solvent (ether, acetone) extracts of tested marine organisms had more inhibitory effect against 5-lipoxygenase than the polar solvent(water) extracts.

• Microbiology and Biotechnology Letters
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• v.10 no.4
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• pp.267-273
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• 1982

Among 12 kinds of ginsenosides in ginseng saponin, ginsenoside-Rb$_1$was contained the most abundantly. But ginsenoside-Rd which is similar to ginsenoside-Rb$_1$in structure, was known to be superior to ginsenoside-Rb$_1$pharmaceutically. In order to convert ginsenoside-Rb$_1$into ginsenoside-Rd by microbial enzyme treatment, a Rhizopus sp. was selected among various strais of molds found in rotten ginseng roots. Enzyme was prepared from the extract of wheat bran koji culture by ammonium sulfate precipitation (1.0 sat'd) and succeeding ammonium sulfate fractionation method (0.6-0.9 sat'd). For the purpose of use as substrate, saponins were purified by the several purification steps from alcohol extract of red ginseng roots. We obtained the total saponin which was composed of 36.5% of ginsenoside Rb$_1$, 12.2% of ginsenoside-Rd and other ginsenosides. For increase of ginsenoside-Rb$_1$ component ratio, we also obtained further purified ginsenoside-Rb group saponin containing 54.5% of ginsenoside-Rb$_1$, 1.1% of ginsenoside- Rd and other ginsenosides from purified the total saponin. In the enzymatic reaction system including the total saponin or the ginsenoside-Rb group saponin, we confirmed the specific conversion of ginsenoside-Rb$_1$to ginsenoside-Rd proportionally and no change of any other ginsenoside patterns by thin layer chromatography and high performance liquid chromatography.

• Journal of Nutrition and Health
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• v.41 no.5
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• pp.428-438
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• 2008

Choline is important for normal membrane function, acetylcholine synthesis and methyl group metabolism. In this study, 185 food items customarily eaten by Koreans were selected from the data of the 2001 Korean National Health and Nutrition Survey and analyzed on the total choline content of the foods using enzymatic method of choline oxidase. Foods with high choline concentration (mg/100 g) were listed in sequence of quail egg (476.04 mg), dried squid (452.42 mg), beef liver (427.16 mg), pork liver (424.92 mg), tuna canned in oil (414.44 mg), boiled and dried anchovy (381.30 mg), dried Alaskan pollack (378.88 mg), chicken egg (309.88 mg), chicken liver (259.38 mg), soybean (238.62 mg), French bread with garlic (193.18 mg) and barley (183.73 mg). From this result, it is shown that dried fishes, prepared fishes, livers, eggs, pulses and cereals might be categorized as high choline food. Citron tea and green tea showed low choline content below 1 mg. Vegetables and fruits were also categorized into low choline food. No choline was detected in red pepper powder, beer, soju, soybean oil and corn oil out of foods analyzed in this study. Further study is required for analytic procedure of the foods of which results are inconsistent with USDA's data such as rice and wheat flour.

• Korean Journal of Psychosomatic Medicine
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• v.9 no.2
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• pp.194-202
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• 2001

Objectives : Many studies have shown an association between serum lipid concentrations and psychologic characteristics. However, conflicting results have also been reported. This study was designed to find the relationship between serum lipid levels(cholesterol and triglycerides) and psychologic characteristics(impulsiveness, aggressiveness, depressiveness) in adolescents. Methods : Serum cholesterol concentration, serum triglycerides concentration, complete blood count, electrolytes, liver function test, and blood sugar level were measured by overnight fasting blood sampling and urinalysis was also conducted in 407 high school students. Impulsiveness level was measured by Barratt Impulsiveness Scale(BIS). Aggressiveness level was measured by Buss-Durkee Hostility Inventory(BDHI). Depressiveness level was measured by Beck Depression Inventory(BDI). Serum cholesterol was measured by standard enzymatic assay and serum triglycerides was measured by Boehringer Mannheim method. Results : 1) Low cholesterol group(<15 percentile) were found to have significantly higher BIS score than high cholesterol group(>85 percentile) in female. Female low cholesterol group were also found to have significantly higher motor impulsivity score, a subscale of BIS, than high cholesterol group. 2) High triglycerides group(>85 percentile) were found to have significantly higher BDI score than low triglycerides group(<15 percentile) in male and female separately. Especially, male high triglycerides group were also found to have significantly higher BIS and motor impulsivity score than low triglycerides group. Conclusion : These results support the previous hypothesis that serum lipid levels(cholesterol and triglycerides) affect human psychologic characteristics.

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.588-596
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• 2018

An endo-${\beta}$-1,4-glucanase gene, cel9K, was cloned using the shot-gun method from Paenibacillus sp. X4, which was isolated from alpine soil. The gene was 2,994 bp in length, encoding a protein of 997 amino acid residues with a predicted signal peptide composed of 32 amino acid residues. Cel9K was a multimodular enzyme, and the molecular mass and theoretical pI of the mature Cel9K were 103.5 kDa and 4.81, respectively. Cel9K contains the GGxxDAGD, PHHR, GAxxGG, YxDDI, and EVxxDYN motifs found in most glycoside hydrolase family 9 (GH9) members. The protein sequence showed the highest similarity (88%) with the cellulase of Bacillus sp. BP23 in comparison with the enzymes with reported properties. The enzyme was purified by chromatography using HiTrap Q, CHT-II, and HiTrap Butyl HP. Using SDS-PAGE/activity staining, the molecular mass of Cel9K was estimated to be 93 kDa, which is a truncated form produced by the proteolytic cleavage of its C-terminus. Cel9K was optimally active at pH 5.5 and $50^{\circ}C$ and showed a half-life of 59.2 min at $50^{\circ}C$. The CMCase activity was increased to more than 150% in the presence of 2 mM $Na^+$, $K^+$, and $Ba^{2+}$, but decreased significantly to less than 50% by $Mn^{2+}$ and $Co^{2+}$. The addition of Cel9K to a commercial enzyme set (Celluclast 1.5L + Novozym 188) increased the saccharification of the pretreated reed and rice straw powders by 30.4% and 15.9%, respectively. The results suggest that Cel9K can be used to enhance the enzymatic conversion of lignocellulosic biomass to reducing sugars as an additive.