• Journal of the Korean Society of Food Culture
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• v.34 no.2
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• pp.224-232
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• 2019

This study evaluated the physicochemical and microbial quality characteristic of seasonal commercial kimchi for hygienic safety levels. The pH of seasonal commercial kimchi was 3.84-6.36 and the titratable acidity and salinity of the samples were 0.21-1.16 and 1.19-1.54%, respectively. The content of nitrate and nitrite in the commercial kimchi were lower in the spring and summer, which was affected by acidic condition of the kimchi depending on fermentation. Heavy metal contents in commercial kimchi are not an issue because they were detected only at very low levels. The total aerobic bacteria and coliforms counts ranged from 5.25 to 8.44 Log CFU/g and 0.00 to 5.08 Log CFU/g, respectively. The total aerobic bacteria and coliforms were detected more in summer than in the other seasons. E. coli was detected in three of the samples tested. Food-borne pathogens were not detected in any of the samples except for B. cereus. B. cereus was detected in the fall in more than 70% of samples. These results suggest that commercial kimchi distributed in the fall maintain the quality properties and the microbiological safety of kimchi compared to the other seasons. Therefore, further studies as an effective distribution system for the particular seasons will be needed to guarantee the hygienic safety levels of commercial kimchi required by the consumers.

• Journal of Dairy Science and Biotechnology
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• v.36 no.4
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• pp.208-219
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• 2018

Emergence of drug resistant strains of Salmonella enterica threatens milk processing and related dairy industries, thereby increasing the need for development of new anti-bacterials. Developments of antibacterial drugs are largely aimed to target the bacterial envelope, but screening their efficacy on bacterial envelope is laborious. This study presents a potential biosensor for envelope-specific stress in which a gfp reporter gene fused to spy gene encoding a periplasmic chaperone protein Spy (spheroplast protein y) that can sense envelope stress signals transduced by two major two-component signal transduction systems BaeSR and CpxAR in Salmonella enterica serovars Enteritidis and S. Gallinarum. Using spy-gfp operon fusions in S. Enterititis and S. Gallinarum, we found that spy transcription in both serovars was greatly induced when Salmonella cells were forming the spheroplast and were treated with ethanol or a membrane-disrupting antibiotic polymyxin B. These envelope stress-specific inductions of spy transcription were abrogated in mutant Salmonella lacking either BaeR or CpxR. Results illustrate that induction of Spy expression can be efficiently triggered by two-component signal transduction systems sensing envelope stress conditions, and thereby suggest that monitoring the spy transcription by spy-gfp operon fusions would be helpful to determine if developing antimicrobials can damage envelopes of S. Enteritidis and S. Gallinarum.

• Journal of Microbiology and Biotechnology
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• v.32 no.2
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• pp.187-194
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• 2022

Two α-ʟ-arabinofuranosidases (BfdABF1 and BfdABF3) and a β-ᴅ-xylosidase (BfdXYL2) genes were cloned from Bifidobacterium dentium ATCC 27679, and functionally expressed in E. coli BL21(DE3). BfdABF1 showed the highest activity in 50 mM sodium acetate buffer at pH 5.0 and 25℃. This exo-enzyme could hydrolyze p-nitrophenyl arabinofuranoside, arabino-oligosaccharides (AOS), arabinoxylo-oligosaccharides (AXOS) such as 3²-α-ʟ-arabinofuranosyl-xylobiose (A³X), and 2³-α-ʟ-arabinofuranosyl-xylotriose (A²XX), whereas hardly hydrolyzed polymeric substrates such as debranched arabinan and arabinoxylans. BfdABF1 is a typical exo-ABF with the higher specific activity on the oligomeric substrates than the polymers. It prefers to α-(1,2)-ʟ-arabinofuranosidic linkages compared to α-(1,3)-linkages. Especially, BfdABF1 could slowly hydrolyze 2³,3³-di-α-ʟ-arabinofuranosyl-xylotriose (A²⁺³XX). Meanwhile, BfdABF3 showed the highest activity in sodium acetate at pH 6.0 and 50℃, and it has the exclusively high activities on AXOS such as A³X and A²XX. BfdABF3 mainly catalyzes the removal of ʟ-arabinose side chains from various AXOS. BfdXYL2 exhibited the highest activity in sodium citrate at pH 5.0 and 55℃, and it specifically hydrolyzed p-nitrophenyl xylopyranoside and xylo-oligosaccharides (XOS). Also, BfdXYL2 could slowly hydrolyze AOS and AXOS such as A³X. Based on the detailed hydrolytic modes of action of three exo-hydrolases (BfdABF1, BfdABF3, and BfdXYL2) from Bf. dentium, their probable roles in the hemiceullose-utilization system of Bf. dentium are proposed in the present study. These intracellular exo-hydrolases can synergistically produce ʟ-arabinose and ᴅ-xylose from various AOS, XOS, and AXOS.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.49-58
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• 2010

The objectives of this study were to investigate the microbial contamination levels on food service in university and to provide the information of microbial contamination to improve food safety. A total of 288 samples were collected during summer and winter season between 2006 and 2008 from 4 food services located in the university in Western Gyeongnam and were used to detect sanitary indicator bacteria [aerobic plate count (APC), coliform, and Escherichia coli] and pathogenic bacteria (Staphylococcus aureus, Salmonella spp.). As a result, APC and coliform for hand and kitchen utensils which are used often by the employee were detected at high levels of 1.1~5.5 and 1.3~5.3 log CFU/($100\;cm^2$, hand), respectively. The contamination levels of APC and coliform in cooked foods and drinking water were 0.8~6.4 and 1.3~5.0 log CFU/(g, mL), respectively. Especially, the cooked foods showed the highest contamination for APC (2.1~6.4 log CFU/g) and coliform (1.0~5.0 log CFU/g). We think the reason that the cooked foods may be contaminated with APC and coliform on cooking process by using employee's hand and kitchen utensils. Moreover, S. aureus for hand and kitchen utensils was detected at levels of 2.8~3.0 and 2.0~2.3 log CFU/(g, hand), but Salmonella spp. was not detected. According to the above results, contamination levels of the samples were mostly decreased irrespective of summer and winter season. The results obtained indicated that it is necessary to periodic monitoring for microorganism contamination and education about personal and environmental hygiene to employee for ensuring food safety of food service in university.

• Korean Journal of Poultry Science
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• v.32 no.1
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• pp.15-21
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• 2005

This Study was conducted to investigate the effects of microbial phytase in low phosphirus and calcium level diet on the performance and nutrient digestibility in laying hens. One hundred ninety two, 50 wks old, ISA brown commerical layers were used for 12 weeks feeding trial after 7-d adjustment period. Four dietary treatments included CON(control; Co.), P2 ($0.06\%$ Natuphos, BASF) and P3 ($0.06\%$ PHOSMAX, GENOFOCUS). Ca and available P concentrations of P1, P2 and P3 were 90 and $50\%$ of NRC recommecdations to accentuate difference in response to phytase availability. In whole period, egg production was not affected by treatments. At 12 weeks, egg weight was significantly increased in adding phytase treatments (P<0.05). Egg shell thickness was increased in P1, P2 and P3 treatments compared with control (P<0.05) at 9 weeks. Ca concentration of serum tended to decrease in P1 treatment without significant difference (P>0.05). Ca and P concentrations of tibia were higher in layers fed dietary phyrase than those fed control diet without significant difference (P>0.05). Digestibilities of DM, N and ash were improved in P1 treatment compared with P2 and P3 treatments (P<0.05). Ca and P digestibilities were the highest in P2 treatment (P>0.05), but was not significant difference between control and P1 treatments.

• Journal of agriculture & life science
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• v.46 no.3
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• pp.97-108
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• 2012

Physical, chemical and biological hazards of strawberry farms at the cultivation stage were analyzed to establish the GAP(Good Agricultural Practice) system. Samples were collected from the plants, cultivation environments(water, soil and air), and personal hygiene (hand, glove, and clothes) of three strawberry farms(A, B, and C) and were tested to analyze physical, chemical (heavy metals and pesticide residues), and biological(sanitary indications and foodborne pathogens) hazards. Physical hazards such as insects and pieces of metal and glass were found in the strawberry farms and can be potential bow for strawberry products. Heavy metal and pesticide residue as chemical hazards were detected at levels lower than the regulation limit. In case of biological hazards, total bacteria and coliform were detected at the levels of 1.6~7.3 and 1.3~5.6 log CFU/g, leaf, mL, hand or $100cm^2$. However, Escherichia coli was not detected in all samples. Bacillus cereus and Staphylococuus aureus were detected at levels of ${\leq}$ 1.1~6.1 log CFU and 4.7~5.4 log CFU/g, mL, hand or $100cm^2$, whereas Listeria monocytogenes, E. coli O157 and Salmonella spp. were not detected in all samples. This study demonstrates that various harzards were in strawberry farms at the growing stage. Therefore proper management such as GAP is needed to prevent the occurrence of food poisoning associated with the hazards revealed in this study.

• Food Science and Preservation
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• v.17 no.5
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• pp.586-594
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• 2010

We evaluated changes in the microbiological quality and safety of food items (vegetables, seaweed, and processed food) supplied to elementary school food services to evaluate the distribution/delivery system. Pretreated vegetables, seaweed, and processed food were delivered to schools in refrigerated (${\leq}10^{\circ}C$) vans that made several delivery stops before arriving at the schools. During the distribution stage, total plate and coliforms counts were: bellflower roots $7.6{\times}10^5-6.7{\times}10^6$ and $5.8{\times}10^4-5.2{\times}10^5$ CFU/g; blanched bracken $4.5{\times}10^3-2.1{\times}10^5$, $5.0{\times}10^3-1{\times}10^4$ CFU/g; onion $1.2{\times}10^4-1.4{\times}10^4$, $5.0{\times}10$ CFU/g; soybean sprouts $9.6{\times}10^4-6.3{\times}10^7$ and $1.1{\times}10^3-1.2{\times}10^7$ CFU/g; soybean curd < $10-9.7{\times}10^5$ and < $10-2.3{\times}10^5$ CFU/g; and starch jelly < $10-3.8{\times}10^3$ and <10 CFU/g. Bacillus cereus < $10-4.1{\times}10^2$ CFU/g, Escherichia coli $1.0{\times}10-2.0{\times}10$ CFU/g, and Staphylococcus aureus $1.3{\times}10^2-4.1{\times}10^2$ CFU/g were detected on peeled bellflower, whereas B. cereus < $10-4.1{\times}10^2$ CFU/g, Listeria monocytogenes $1.0{\times}10-4.5{\times}10^2$ CFU/g, and S. aureus $1.8{\times}10^2-4.5{\times}10^2$ CFU/g, were detected on soybean sprouts. Most food items were double-wrapped in vinyl and placed in corrugated cardboard boxes prior to delivery, but the boxes, when placed in vans, were not segregated from other food items being delivered to schools and other destinations.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.178-184
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• 2011

In this study, the antibacterial, antioxidative and inhibitory effects of Allium cepa peel extracts on tyrosinase and elastase were investigated. MIC values of the ethyl acetate fraction of Allium cepa peel on especially, S. aureus among the skin resident flora (Staphylococcus aureus, S. aureus; Propionibacterium acnes, P. acnes; Pityrosporum ovale, P. ovale; Escherichia coli, E. coli) were 0.06%. The aglycone fraction showed more excellent free radical (1,1-diphenyl-2-picrylhydrazyl radical, DPPH) scavenging activity ($FSC_{50}=5.05{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of the ethyl acetate fraction and aglycone fraction in the luminol-dependent $Fe^{3+}-EDTA/H_2O_2$ system were 0.05 and $0.03{\mu}g/mL$, respectively. The cellular protective effect of the aglycone fraction on the rose-bengal sensitized photohemolysis of human erythrocytes exhibited more prominent (${\tau}_{50}$, 480 min at $25{\mu}g/mL$). The inhibitory effects ($IC_{50}$) of the ethyl acetate fraction and aglycone fraction on tyrosinase were 9.16 and $8.68{\mu}g/mL$, the inhibitory effect ($IC_{50}$) of the aglycone fraction on elastase was $14.12{\mu}g/mL$ The transepidermal water loss of the cream containing 0.1% ethyl acetate fraction was decreased from $8.3g/m^2h$ in control to $6.8g/m^2h$ in the subjects applied with cream containing the ethyl acetate fraction. These results indicate that extract/fractions of Allium cepa peel can function as antioxidant in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS, and possibly as antiaging agents. Allium cepa peel extract could be used as a new cosmeceutical for whitening and anti-wrinkle products.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.2
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• pp.159-169
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• 2009

In this study, the antibacterial activity, antioxidative effects, inhibitory effects on tyrosinase, inhibitory effects on elastase, and components of Quercus acutissima Carruth leaf extracts were investigated. MIC values of ethyl acetate fraction from Q. acutissima Carruth leaf on P. acnes, S. aureus, P. ovale, and E. coli were 0.13 %, 0.25 %, 0.13 % and 0.25 %, respectively. The results showed that the antibacterial activity of the ethyl acetate fraction was the highest in the S. aureus, P. acnes, and P. ovale. The free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$) of extract/fractions of Q. acutissima Carruth. leaf was in the order: 50 % ethanol extract (12.13 ${\mu}g/mL$) < ethyl acetate fraction (7.07 ${\mu}g/mL$) < deglycosylated flavonoid aglycone fraction (6.20 ${\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of some Q. acutissima Carruth leaf extracts on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The order of ROS scavenging activity was 50 % ethanol extract ($OSC_{50}$, 1.81 ${\mu}g/mL$) < ethyl acetate fraction (1.70 ${\mu}g/mL$) < deglycosylated flavonoid aglycone fraction (0.70 ${\mu}g/mL$). Deglycosylated flavonoid aglycone fraction showed the most prominent scavenging activity. The protective effects of extract/fractions of Q. acutissima Carruth leaf on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The Q. acutissima Carruth leaf extracts suppressed photohemolysis in a concentration dependent manner, particularly deglycosylated flavonoid aglycone fraction exhibited the most prominent celluar protective effect (${\tau}50$, 220.00 min at 25 ${\mu}g/mL$). Aglycone fractions obtained from the deglycosylation reaction of ethyl acetate fraction among the Q. acutissima Carruth leaf extracts, showed 3 bands (QA 1, QA2 and QA3) on TLC. TLC chromatogram of ethyl acetate fraction of Q. Carruth. leaf extract revealed 4 bands (QA 1 ${\sim}$ QA 4), Among them, kaempferol (QA 1), quercetin (QA 2), and gallic acid (QA 3) were identified. The inhibitory effect ($IC_{50}$) of aglycone fraction on tyrosinase was 65.7 ${\mu}g/mL$. The inhibitory effect ($IC_{50}$) of aglycone fraction on elastase was 24.50 ${\mu}g/mL$. These results indicate that extract/fractions of Q. acutissima Carruth. can functionized as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS. Extract/fractions of Q. acutissima Corruth can be applicable to new functional cosmetics for antioxidant, antiaging, antibacterial activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.139-147
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• 2021

Livestock manure is used as an organic fertilizer to replace chemical fertilizers after sufficient fermentation in an aerobic bioreactor. On the other hand, liquid manure disposal problems occur repeatedly because soil spraying is restricted during the summer when the crops are growing. To use liquid fertilizer (LF) as an additional nutrient source for crops, it is necessary to reduce the amount of suspended solids (SS) in the liquid fertilizer and secure stability problems against pathogenic microorganisms. This study examined the effects of the simultaneous SS removal and E.coli sterilization in the LF using the microbubble (MB) generator (FeMgO catalyst insertion). The remaining SS were further removed using the integrated microbubble and microfilter system. During the floating process in the MB device, the SS were removed by 57.9%, and the coliform group was not detected (16,200→0 MPN/100 mL). By optimizing the HRT of the integrated system, the removal efficiency of the SS was improved by 92.9% under the 0.1h of HRT condition. After checking the properties of the treated LF, 64.5%, 70.1%, 54.9%, and 51.5% of the TCOD, SCOD, PO4-P, and TN, respectively, were removed. The treated effluent from such an integrated system has a lower SS content than that of the existing LF and does not contain coliforms; therefore, it can be used directly as an additional fertilizer.