• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.127-131
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• 2006

A study was carried out to produce antimicrobial peptides from zein treated with pretenses of six kinds. Among the pretenses of six kinds, zein hydrolysate treated with pepsin showed the highest antimicrobial activity. The zein hydrolysate with pepsin was fractionated with membrane filter (30,000 10,000 and 3,000 molecular weight cut-off) and antimicrobial activity was measured for each fractions. Antimicrobial activity appeared greatly in the fraction below 3,000 (molecular weight cut-off) . The fraction was re-fractionated by HPLC and substances of two peaks collected as a sample to measure antimicrobial activity. All of both peaks showed the antimicrobial activity but 1st peak exhibited a consistently higher antimicrobial activity than 2nd peak. Minimum inhibitory concentrations (MIC) were between 2.5 and 3.0 mg/mL. The peptide was heat-stable since antimicrobial activity was maintained after treated with heat for 20 min at $121^{\circ}C$. N-terminal amino acid sequence of peptide fractionated by HPLC was leucine, glutamic acid, proline, phenylalanine, aspartic acid and argenine. These results indicated that peptide isolated from zein hydrosate with pepsin can use as a natural preservative ingredient in food industry.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.495-500
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• 2013

This study was performed to identify safe natural food preservatives from medicinal herbs and to evaluate the antimicrobial effects of medicinal plants against microorganisms. Medicinal herbs were extracted 3 times with methanol at $45^{\circ}C$ for 3 h and fractionated with n-hexane. The antimicrobial effects of the fractions were determined by measuring the diameter of the inhibition zone by using an agar-well diffusion assay. The MIC of fractions for the inhibition of microorganisms was determined using a microplate reader. The antimicrobial effects of fractions were greater against gram positive bacteria than against gram negative bacteria, but the difference was not significant. The antimicrobial effects of fractions were concentration dependent. While these results have implications, the underlying mechanisms of microbial inactivation need to be further elucidated. The results showed the possibility of developing safer food preservatives.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.464-470
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• 1994

The biological activities of Humulus japonicus were extracted by water and methanol. Methanol was better solvent than water in the extraction for antimicrobial activities against six different species of bacteria and two yeasts. The methanol extract was systematically fractionated with various organic solvents which have different polarities. From the result of antimicrobial activities against six species of bacteria and two species of yeasts, methanol extract was superior to water extract. The methanol extract of Humulus japonicus showed antimicrobial activity against the all species of microorganisms tested except Escherichia coli . The butanol fraction of methanol extract showed antimicrobial effect on the all species tested. The minimal inhibition concentration(MIC) of the butanol fraction on the growth of microorganisms was ranged between $0.1{\sim}0.4%$. The water extract of Humulus japonicus did not show inhibition of the activity of trypsin but methanol extract showed inhibitory activity. The chloroform fraction of methanol extract showed comparatively higher trypsin inhibitory activity than other fractions. The concentration of 50% inhibition$(IC_{50})$ by chloroform fraction was 1.0 mg/ml. Enzyme-inhibitor complex formation was above 90% of the while for 20 min. It was revealed that methanol extract of Humulus japonicus inhibited peroxide production of lard and soybean oil as substrate by antioxidative test. The chloroform fraction of methanol extract had the highest activity. When 0.2% of chloroform fraction was added, induction period of soybean oil and lard were extended 15, 9 days, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.1
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• pp.7-13
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• 2011

This study was conducted to investigate the antimicrobial activity of Ginkgo biloba L. leaves, seed and outer seedcoat against bacteria. Antimicrobial effects of Ginkgo biloba L. leaves (GBL), seed (GBS) and outer seedcoat (GBO) were examined by paper disc method and optical density method to determine minimum inhibition concentration (MIC), and observed by scanning electron microscope (SEM) to figure out the morphological change on the surface when Ginkgo biloba leaves extract was treated. The extracts of GBL, GBS and GBO were extracted by solvents such as methanol, ethanol, water. The methanol extract of GBL and GBO showed the highest antimicrobial activity against Bacillus cereus, Bacillus subtilis, Klebsiella pneumoniae, Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus, Yersinia enterocolitica except Escherichia coli and thus was further fractionated. The MICs of the chloroform fraction of GBL methanol extract were $125{\mu}g$/mL against B. subtilis, and L. monocytogenes; GBO methanol extract were $62.5{\mu}g$/mL against B. cereus and $125{\mu}g$/mL against B. subtilis, and L. monocytogenes. The microorganisms were treated with chloroform extracts ($2000{\mu}g$/mL) of GBL and GBO methanol extracts. It was observed by scanning electron microscope (SEM). The cells were expanded and a part of cell wall was completely destructed by GBL and GBO. Thus Ginkgo biloba L. leaves and outer seedcoat could be further developed into a natural antimicrobial agent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.951-957
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• 2009

In this study, antibacterial activity of extruded ginseng extract by 60 and 80% Et-OH were investigated by agar diffusion assay against two bacteria causing dental caries (Streptococcus mutans and Lactobacillus casei). Extrusion conditions were 20% moisture content $100^{\circ}C$ and $140^{\circ}C$ barrel temperature. The inhibition effect of 60% Et-OH ginseng extract was higher than 80% Et-OH ginseng extract. The minimum inhibitory concentration (MIC) of 80% Et-OH extruded ginseng extract at 140 and $100^{\circ}C$ barrel temperature against L.casei were 100 and 150 mg/mL respectively using broth assay method. The amount of glucosyltransferase (GTase) inhibitory content was the highest in extruded ginseng at $140^{\circ}C$ barrel temperature with 60% Et-OH. Moreover, n-hexane and n-butanol fraction ginseng extract had potential against tested bacteria. Our results demonstrated that antibacterial activities of extruded ginseng extract at $140^{\circ}C$ barrel temperature were more effective than Ex-$100^{\circ}C$, RG and WG.

• Journal of Food Hygiene and Safety
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• v.27 no.2
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• pp.109-116
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• 2012

The study indicated that antimicrobial activity about gram positive and gram negative bacteria of ginger-oleoresin(GO) extract with the condition of ethanol and supercritical fluid extractions. As the concentration of extraction increases, the clear zone of GO ethanol extract also increased dependently. This led the antimicrobial activity of gram positive bacteria to take bigger place than gram negative bacteria especially in Listeria monocytogenes. There was a high antimicrobial activity in E-III treatment where the ratio of the ginger powder extract to ethanol extraction was 1:6. It was quite effective to treat the antimicrobial activity of GO ethanol extract under $80^{\circ}C$ and there was not big difference in the intervals which were the extraction time - 1 to 7 hours. The antimicrobial activity of supercritical fluid extract seemed to take the biggest place in Listeria monocytogenes. From the supercritical fluid extract, it was shown the strong ability of antimicrobial activity in the condition with 100 bar $35^{\circ}C$, 250 bar $35^{\circ}C$ and 250 bar $65^{\circ}C$. Furthermore, according to the case of solvent extract, there was not any significant difference in the antimicrobial activity with condition of extraction. However, there was significant antimicrobial activity in E-III treatment of 100 bar and 500 bar of extraction pressure, and $35^{\circ}C$ and $65^{\circ}C$ of extraction temperature.

• Journal of Aquaculture
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• v.14 no.3
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• pp.157-163
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• 2001

The antibacterial effect of fish diet soaked in the extract of Salvia miltiorriza was tested to determine its levels of antibacterial activity, minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). The extract showed strong activity against gram positive bacteria, but was weak against gram negative bacteria. Concentration levels of 13.4~40.3 and 67.2~403.0 $\mu\textrm{g}$/ml were determined as the MIC and MBC, respectively. However, levels above 403.0 $\mu\textrm{g}$/ml was neither bacteriostatic nor bactericidal against Edwardsiella tarta, a gram negative strain. The fish diet, soaked in the extract of Salvia miltiorriza, inhibited the growth of all strains of Streptococcus genus and Vibrio anguillarum. The relationship formula between weight of fish diet and Salvia miltiorriza extract absorbed into the fish diet was Y＝2.4953X＋3.3276 ($R^2$= 0.9999). The antibacterial activity of the fish diet, soaked in the extract, was stable from 10 to 35$^{\circ}C$ during the storage period of 28 days.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.338-342
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• 2002

Antimicrobial activity of yellow pigment produced by Monascus anka Y7 (Y7) was studied. The crude yellow pigment of Y7 showed antimicrobial activity against some bacteria and yeasts. The diameter of inhibition zone against gram-positive bacteria was a little smaller t]fan that of gram-negative bacteria to the crude yellow pigment. Especially, E2 fraction obtained from the crude yellow pigment by TLC method showed high anti-microbial activity against E. coli.. The fraction had bright yellow pigment, showing fluorescent light and having the maximum absorption at 373 nm. Citrinin, a mycotoxin which had been characterized as an antimicrobial substance from a Monascus strain, was not detected in the E2 fraction and in the crude yellow pigment by the results of TLC and HPLC. This indicates that the antimicrobial activity of Y7 pigments did not any relationship with citrinin. Yellow degree (b/a of Hunters color value) of Y7 pigment was much higher than that of other natural colorants such as annatto, gardenia yellow and carthamus yellow. But the colors of all of the yellow pigments were similar by panels. Thus, the yellow pigment of Y7 could be used as a useful alternative colorant for food industry, having the advantage of antimicrobial activity.

• Korean Journal of Plant Resources
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• v.12 no.4
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• pp.260-268
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• 1999

Crude extract of Coptis japonica root-stem was evaluated for antifungal activity against Phytophthora capsici, Fusarium oxysporum, Colletotrichum dematium, Colletotrichum truncatum, Botrytis cinerea, Botryosphaeria dothidea and Alternaria porri, and antifungal active compound from the extract was identified. In addition, the usefulness of the extract for some plants disease control was investigated. Crude extract of C. japonica root-stem exhibited antifungal activity against P. capsici, F. oxysporum, C. dematium, B. cinerea, B. dothidea and A. porri. Antifungal activity of the substance isolated from C. japonica root-stem was similar to a standard chemical berberine-Cl. Red-pepper fruit rot, sesame stem rot and welsh-onion alternaria leaf spot were effectively controlled by the crude extract of C. japonica root-stem. Phytotoxicity was not observed in the red-pepper and welsh-onion leaves and red-pepper and strawberry fruits with exogenous foliage application of the crude extract. Seeds germination and radicle growth of red-pepper and sesame were inhibited by the crude extract of C. japonica root-stem. 4.24g of yellowish compound per 100g of C. japonica root-stem was obtained. The compound was identified as berberine-Cl by HPLC.

• Journal of Food Hygiene and Safety
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• v.15 no.4
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• pp.277-281
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• 2000

Agar, one of the most abundant marine products has not been utilized extensively because of low level of processing technology in Korea. This research was carried out to improve the utilization of agar and consequent increase in profit. Antibacterial activity of agarooligosaccharides were evaluated against bacteria causing putrefaction and flood poisoning. Addition of 0.4% agarooligosaccharides showed antibacterial activity toward Staphylococcus aureus and Escherichia coli O157:H7; furthermore, autoclave treatment of agarooligosaccharides solution enhanced the antibacterial activity. Agarooligosaccharides showed high stability against the pH change. Addition of amino acid(alanine, lysine, glycine, phenylalanine) in agarooligosaccharides solution enhanced antibacterial activity in E. coli O157:H7, Streptococcus mutans and Staphylococcus aureus.