살모넬라 균주들에서 열처리에 의한 항생제 내성 연구

김수진,방우석,김세훈 한국식품위생안전성학회 2024 한국식품위생안전성학회지 Vol.39 No.1

Salmonella spp. 11 strains에 대해 저온 열처리(50oC) 3, 6, 9분 후 MIC값을 측정하여 항생제 내성을 알아보았다. Chloramphenicol에 대해 대조군과 열처리한 strains 대부분 에서 감수성(S)이 있는 것으로 나타났고, 열처리한 strains 의 MIC값은 대조군과 비교하였을 때 유지되거나 감소하 였다. Ciprofloxacin에 대해 대조군과 열처리한 strains는 대 부분 감수성(S)이 있거나 중간(I)을 나타냈다. Tetracycline 은 모든 strains에서 감수성(S)이 있는 것으로 나타났으며, S. Gaminara BAA 711에 대해 열처리 후 MIC값이 증가 하였다. Gentamicin에 대해 대조군 strains들에서 감수성을 나타낸 strains가 3 strains, 중간을 나타낸 strains 2 strains, 내성을 가진 strains가 6 strains였으며, 이 중 S. Heidelberg ATCC 8326는 MIC값을 측정했을 때 대조군에서 MIC값 이 8 μg/mL로 MIC break point가 중간이었으나, 3분과 9 분 열처리 후 MIC값이 16 μg/mL로 증가하여 break point 가 내성을 나타냈다. 본 실험결과 Salmonella spp. 11 strains 에 대해서 저온 열처리 후 열내성 효과에 의한 항생제 내성을 알아봤을 때 ciprofloxacin에서 S. Montevideo BAA 710을 3, 6분 열처리한 경우, gentamicin에서 S. Enteritidis 109 D1을 3분 처리한 경우와 S. Heidelberg ATCC 8326 을 3, 9분 처리한 경우, tetracycline에서 S. Gaminara BAA 711을 6, 9분 처리한 경우 MIC값이 증가하였다. 후속 연 구를 통해 Salmonella spp. strains에 대해 열처리 후 열내 성 효과를 나타내는 병원성 유전자의 특성에 대한 지속적 인 연구가 필요하다. Salmonella is widely prevalent in various environments and often detected in poultry. In this study, we investigated the effect of heat treatment on heat resistance via measuring the minimum inhibitory concentration (MIC) values of antibiotics after 3, 6, and 9 min of acclimatization to mild heat treatment (50oC) against 11 strains of Salmonella spp. Most strains were susceptible to chloramphenicol and their MIC values were maintained or decreased after heat treatment compared to the control. Most control and heat-treated strains showed susceptibility or intermediate resistance to ciprofloxacin. All isolates were susceptible to tetracycline, with the MIC increasing after heat treatment for S. Gaminara BAA 711. In the control, three, two, and six strains were susceptible, intermediate resistance, and resistant to gentamicin, respectively. Among them, S. Heidelberg ATCC 8326 had an intermediate MIC breakpoint of 8 μg/mL in the control; however, after 3 and 9 min of heat treatment, the MIC value increased to 16 μg/mL, indicating it to be resistant. The results of this study revealed the changes in antibiotic resistance in some of the 11 strains after heat treatment. MIC values of ciprofloxacin increased when S. Montevideo BAA 710 was heat treated for 3 and 6 min. MIC values of gentamicin increased after 3 min of heat treatment for S. Enteritidis 109 D1 and after 3 and 9 minutes of heat treatment for S. Heidelberg ATCC 8326. The MIC value of tetracycline increased when S. Gaminara BAA 711 was heat treated for 6 and 9 min.

Fumaric acid와 mild heat의 병합 처리에 따른 시금치의 저장 중 미생물 제어 효과

손현정 ( Hyeon Jeong Son ),강지훈 ( Ji Hoon Kang ),오덕환 ( Deog Hwan Oh ),민세철 ( Sea Cheol Min ),송경빈 ( Kyung Bin Song ) 한국응용생명화학회 2016 Journal of Applied Biological Chemistry (J. Appl. Vol.59 No.1

The objective of this study was to examine the combined effect of fumaric acid with mild heat on the inactivation of microorganisms on spinach. Spinach leaves were in℃ulated with Escherichia coli O157:H7 and Listeria mon℃ytogenes. Based on the results of single treatment of fumaric acid (0.1, 0.3, and 0.5%) or mild heat (40, 50, and 60℃) regarding the inactivation of the in℃ulated bacteria, the optimal condition for the combined treatment was suggested to be 0.5% fumaric acid and mild heat treatment at 50℃ for 5 min. The combined treatment of fumaric acid with mild heat caused 2.53 and 2.62 log reductions of the populations of L. mon℃ytogenes and E. coli O157:H7, respectively. In addition, during storage of fresh spinach at 4℃ for 12 d, the combined treatment reduced initially the populations of total aerobic bacteria by 2.77 log CFU/g compared with the control. In particular, after 12 d of storage, the population of total aerobic bacteria for the combined treatment sample was 4.84 log CFU/g, whereas the control sample had 6.66 log CFU/g. Color and vitamin C content of spinach samples were not altered significantly by the combined treatment during storage. These results indicate that the combined treatment of fumaric acid with mild heat is an effective method to control microorganisms on spinach during storage.

후춧가루에 인위접종된 Escherichia coli O157:H7, Salmonella Typhimurium에 대한 UV-C와mild heat의 살균 효과

곽승해,김진희,오세욱 한국식품위생안전성학회 2018 한국식품위생안전성학회지 Vol.33 No.6

The reduction effect of UV-C irradiation and mild heat treatment was examined against Escherichia coli O157:H7 and Salmonella Typhimurium on black pepper powder. E. coli O157:H7 (ATCC 35150) and S. Typhimurium (ATCC 19585) were inoculated onto black pepper powder at approximately 〖10〗^7and 〖10〗^6CFU/g, respectively. E. coli O157:H7 and S. Typhimurium were treated with UV-C and mild heat at 60℃. A UV-C intensity (2.32 W/cm2 ) was used for 10 min to 70 min at 60℃. After UV-C and heat treatment at 60℃ , microbial analysis and color change of black pepper powder was conducted. E. coli O157:H7 and S. Typhimurium were reduced by a level of 1.89 and 2.24 log CFU/g, respectively, when treated with UV-C alone for 70 min. And E. coli O157:H7 and S. Typhimurium were reduced by 2.22, 5.10 log CFU/g, respectively, when treated with mild heat treatment at 60℃alone for 70 min. But when combined with UV-C and mild heat, it showed higher level of reduction were by 2.46, 5.70 log CFU/g.S. Typhimurium was more easily reduced than E. coli O157:H7. Color values were not significantly (p> 0.05) different in all treated samples. Therefore, these results suggest that the combined treatment with UV-C and mild heat was effective to inactivate the food pathogens in black pepper powder and can be used as a food industrial microbial intervention method.

Inactivation of foodborne pathogens in powdered red pepper (Capsicum annuum L.) using combined UV-C irradiation and mild heat treatment

Cheon, H.L.,Shin, J.Y.,Park, K.H.,Chung, M.S.,Kang, D.H. Butterworths ; Taylor Francis ; Elsevier Science 2015 Food Control Vol.50 No.-

This study was performed to investigate the effectiveness of combined ultraviolet (UV-C) irradiation and mild heating as an alternative to conventional inactivation of foodborne pathogens, including Escherichia coli O157:H7 and Salmonella Typhimurium on powdered red pepper. A cocktail of three strains of E. coli O157:H7 ATCC 35150, ATCC 43889, ATCC 43890) and S. Typhimurium (ATCC 19585, ATCC 43971, DT 104) was inoculated onto powdered red pepper and then treated with UV-C irradiation and mild heat. A constant UV intensity (3.40 mW/cm<SUP>2</SUP>) of the emitting lamps was applied to samples for 5, and 10 min at 25, 35, 45, 55, and 65 <SUP>o</SUP>C, respectively. Also, quality change of powdered red pepper was measured in order to identify the efficiency of combined treatment. The reduction levels of E. coli O157:H7 and S. Typhimurium on powdered red pepper when treated with UV-C irradiation alone at 20.4 kJ/m<SUP>2</SUP> for 10 min was 0.22 and 0.29 log CFU/g, respectively. While, combined treatment with mild heating at 65 <SUP>o</SUP>C reduced the surviving numbers of each pathogens by 2.88 and 3.06 log CFU/g, respectively. Although the inactivation efficiency was influenced less by the UV-C radiation dose, the synergistic effect was observed with increasing temperature and UV-C radiation dose. CIE color value and extractable color value were not significantly (P > 0.05) different between non-treated and combination treated samples. The moisture and capsaicinoids contents showed significant (P < 0.05) differences when treated at 65 <SUP>o</SUP>C because of sample drying during heat treatment. Therefore, these results suggest that UV-C irradiation combined with mild heating can be utilized by the food industry in order to effectively inactivate E. coli O157:H7 and S. Typhimurium without incurring quality deterioration of powdered red pepper.

Stress Tolerance of Bifidobacterium infantis ATCC 27920 to Mild-heat Adaptation

Seoku Kang,Younghoon Kim,Inshick Cho,Ja-Heon Kang,Ilbyung Chung,Kwang-Hyun Kim,Sejong Oh 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.1

Two-dimensional gel electrophoresis (2-DE) was employed to assess the thermo-tolerance characteristics of Bifidobacterium infantis ATCC 27920 to mild heat adaptation. When exposed to various heat levels, pH, and hydrogen peroxide (H₂O₂) stress conditions, B. infantis ATCC 27920 exhibited high level of stress resistance. Under mild-heat treatment (46℃), no significant change in viability level was observed after 2 hr. Interestingly, improved viability was observed in mild-heat adapted (46℃ for 1 hr) cultures exposed to 55℃, in comparison to control experiments. Viability was not affected by pH, bile, and H₂O₂ stress conditions. 2-DE analysis revealed those mild-heat adaptation up-regulated 4 proteins and down-regulated 3 proteins. Among these protein spots, isopropylmalate dehydratase (leuD), glycosyltransferase (glgA), and ribosomal protein L5 (rplE) were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS).

압연 클래드된 Ti/Mild steel/Ti 재의 계면확산층과 접합력에 미치는 후열처리온도의 영향

이상목 ( Sang Mok Lee ),김수민 ( Su Min Kim ),위세나 ( Se Na We ),배동현 ( Dong Hyun Bae ),이근안 ( Geun An Lee ),이종섭 ( Jong Sup Lee ),김용배 ( Yong Bae Kim ),배동수 ( Dong Su Bae ) 대한금속재료학회 ( 구 대한금속학회 ) 2012 대한금속·재료학회지 Vol.50 No.4

The aim of this study is to investigate the effect of post heat treatment on bonding properties of roll cladded Ti/MS/Ti materials. First grade Ti sheets and SPCC mild steel sheets were prepared and then Ti/MS/Ti clad materials were fabricated by a cold rolling and post heat treatment process. Microstructure and point analysis of the Ti/MS interfaces were performed using the SEM and EDX Analyser. Diffusion bonding was observed at the interfaces of Ti/MS. The thickness of the diffusion layer increased with post heat treatment temperature and the diffusion layer was verified as having (ε+ζ)+(ζ+β-Ti) intermetallic compounds at 700℃ and an (ζ+β-Ti) intermetallic compound at 800℃, respectively. The micro Knoop hardness of mild steel decreased with post heat treatment temperature; however, those of Ti decreased at a range of 500~600 ℃ and showed a uniform value until 800℃ and then increased rapidly up to 900℃. The micro Knoop hardness value of the diffusion layer increased up to 700℃ and then saturated with post heat treatment. A T-type peel test was used to estimate the bonding forces of Ti/Mild steel interfaces. The bonding forces decreased up to 800℃ and then increased slightly with post heat treatment. The optimized temperature ranges for post heat treatment were 500~600℃ to obtain the proper formability for an additional plastic deformation process.

카프릴산 및 미열의 병용 처리를 통한 신선채소 내 병원성 대장균 O157:H7 저감화 기술 개발

이소은,오현진,김봉선,백지현,정민우,배재우 한국식품과학회 2024 한국식품과학회지 Vol.56 No.1

This study aimed to examine the bactericidal effects of caprylic acid (CA) with mild heat on Escherichia coli O157:H7. The combined treatment showed better antimicrobial effects than individual treatments in an in vitro test. When green onion, onion, red chili pepper, Korean zucchini were treated with CA in combination with mild heat (50oC), it showed enhanced antimicrobial effects compared with CA alone. In addition, CA (20 to 30 mM) and 50oC mild heat treatment did not affect the chromaticity of all fresh produce except zucchini, which was apparently distinguishable with naked eyes. Importantly, no significant decrease in the hardness of fresh produce was observed after the combined treatment, which showed that the freshness of fresh produce was maintained. Taken together, these results indicated that a combined treatment with low CA concentration (20 to 30 mM) with mild heat (50oC) can effectively control E. coli O157:H7 in fresh produce.

Analysis of <i>Staphylococcus aureus</i> cell viability, sublethal injury and death induced by synergistic combination of ultrasound and mild heat

Li, Jiao,Suo, Yuanjie,Liao, Xinyu,Ahn, Juhee,Liu, Donghong,Chen, Shiguo,Ye, Xingqian,Ding, Tian Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>This study was designed to investigate the combined effects of ultrasound and mild heat on the viability of <I>S. aureus</I> in association with the cell membrane integrity and intracellular enzyme activity. Cells were treated by ultrasound under 55°C for 3, 5, 7, 10, and 15min. The dynamic changes of <I>S. aureus</I> cell viability, sublethal injury and death were evaluated using flow cytometric assay. Microscopies were applied to identify the morphological appearance, ultrastructure and topography of <I>S. aureus</I>. The results showed the membrane damage was synchronous with esterase inhibition during the exposure to sonication, leading to the immediate lethal effect. On the other hand, bacteria under the mild heat at 55°C were inactivated via a sublethal injury process. The different lethal modes were observed between sonication and mild heat treatments, which could synergistically inactivate <I>S. aureus</I>. The antibacterial value of thermo-sonication was greater than the sum of the individual treatments. The thermo-sonication combination synergistically reduced the number of sublethal cells and also resulted in severe cell damage.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The lethal modes induced by ultrasound and mild heat were different. </LI> <LI> Two sterilization techniques were synergistic in cell inactivation. </LI> <LI> Cell viability, sublethal injury and death were distinguished by flow cytometry. </LI> <LI> Thermo-sonication treatment reduced the number of sublethal cells. </LI> <LI> Microscopies revealed <I>S. aureus</I> morphological changes and bactericidal effect. </LI> </UL> </P>

Inactivation effect of UV-C and mild heat treatment against Salmonella Typhimurium and Escherichia coli O157:H7 on black pepper powder

김미정,김진희,오세욱 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.2

In this study, UV-C and mild heat treatmentswere used alone or in combination for the inactivation ofSalmonella Typhimurium and Escherichia coli O157:H7on the black pepper powder. The treated pepper powderwas analyzed microbiologically, and the physicochemicalproperties of the pepper powder were examined. UV-Ccombined with heat treatment at 60 C most effectivelyinactivated the pathogens. However, heat treatment at60 C produced many injured cells and greatly reducedmoisture content of the pepper powder. UV-C combinedwith heat treatment at 45 C showed significantly(p\0.05) similar inactivation results as that with heattreatment at 60 C after 18 min. In addition, the combinedtreatment minimized the moisture loss and color change ofthe pepper powder compared to heat treatment at 60 C. Thus, UV-C and heat treatment at 45 C can effectivelyinactivate pathogens while maintaining the quality of blackpepper powder.

Development of hydrophobicity and selective separation of hazardous chlorinated plastics by mild heat treatment after PAC coating and froth flotation

Thanh Truc, Nguyen Thi,Lee, Chi-Hyeon,Lee, Byeong-Kyu,Mallampati, Srinivasa Reddy Elsevier 2017 Journal of hazardous materials Vol.321 No.-

<P><B>Abstract</B></P> <P>Polyvinyl chloride (PVC) containing chlorine can release highly toxic materials and persistent organic pollutants if improperly disposed of. The combined technique of powder activated carbon (PAC) coating and mild heat treatment has been found to selectively change the surface hydrophobicity of PVC, enhancing its wettability and thereby promoting its separation from heavy plastic mixtures included polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS) and acrylonitrile butadiene styrene (ABS) by means of froth flotation. The combined treatments helped to rearrange the surface components and make PVC more hydrophobic, while the remaining plastics became more hydrophilic. After the treatments at 150°C for 80s the contact angle of the PVC was greatly increased from 90.5 to 97.9°. The SEM and AFM reveal that the surface morphology and roughness changes on the PVC surface. XPS and FT-IR results further confirmed an increase of hydrophobic functional groups on the PVC surface. At the optimized froth flotation and subsequent mixing at 150rpm, 100% of PVC was recovered from the remaining plastic mixture with 93.8% purity. The combined technique can provide a simple and effective method for the selective separation of PVC from heavy plastics mixtures to facilitate easy industrial recycling.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PAC coating and mild heat treatment were combined for selective wetting of PVC. </LI> <LI> The combined treatment rearranged the PVC surface and increased its hydrophobicity. </LI> <LI> Optimized froth flotation was crucial for selective separation of the treated PVC. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>