• 한국식품과학회지
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• 제37권1호
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• pp.129-133
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• 2005

Minimally processed and refrigerated(MPR) 셀러드의 미생물학적 안전성 및 저장성 증대를 위하여 이산화염소와 citric acid 처리를 이용하여 실험한 결과 총 호기성 세균을 3.75 log cycle, 효모와 곰팡이는 3.47 log cycle, 대장균은 3.41 log cycle, Listeria 속은 3.38 log cycle 감소시켰다. 물로 세척한 경우는 샐러드의 미생물을 효과적으로 제거하지 못한 반면 화학적 처리구는 생육 미생물을 3.3-3.7 log cycle 감소시킴으로써 식품의 미생물학적 안전성을 보장해 주었다. 또한 샐러드 저장 중 효소적 갈변 원인인 polyphenoloxidase의 활성을 감소시켜 대구조에 비해서 49.73%의 감소를 보였다. 따라서 이산화염소와 citric acid를 이용한 화학적 처리는 MPR 샐러드의 위생학적 안전성을 보장해 주고 또한 갈변 효소의 활성을 억제함으로써 저장성을 증대시키고 유통기간 연장에 도움이 된다고 판단된다.

• Food Science and Biotechnology
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• 제16권6호
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• pp.1018-1022
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• 2007

Effect of aqueous chlorine dioxide treatment on the microbial growth and quality changes of strawberries during storage was examined. Strawberries were treated with 5, 10, and 50 ppm of chlorine dioxide solution, and stored at $4{\pm}1^{\circ}C$. Total aerobic bacteria in strawberries treated at 50 ppm of chlorine dioxide were increased from 1.40 to 2.10 log CFU/g after 7 days, while increasing in the control from 2.75 to 4.32 log CFU/g. Yeasts and molds in strawberries treated at 50 ppm of chlorine dioxide were increased from 1.10 to 1.97 log CFU/g after 7 days, while the control was increased from 2.55 to 4.50 log CFU/g. The pH and titratable acidity of strawberries were not significantly different among treatments. Sensory evaluation results showed that chlorine dioxide-treated strawberries had better sensory scores than the control. These results indicate that chlorine dioxide treatment could be useful in improving the microbial safety and qualities of strawberries during storage.

• Journal of Microbiology and Biotechnology
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• 제27권5호
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• pp.995-1004
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• 2017

Culture-dependent methods, such as heterotrophic plate counting (HPC), are usually applied to evaluate the bacteriological quality of hemodialysis water. However, these methods cannot detect the uncultured or viable but non-culturable (VBNC) bacteria, both of which may be quantitatively predominant throughout the hemodialysis water treatment system. Therefore, propidium monoazide (PMA)-qPCR associated with HPC was used together to profile the distribution of the total viable bacteria in such a system. Moreover, high-throughput sequencing of 16S rRNA gene amplicons was utilized to analyze the microbial community structure and diversity. The HPC results indicated that the total bacterial counts conformed to the standards, yet the bacteria amounts were abruptly enhanced after carbon filter treatment. Nevertheless, the bacterial counts detected by PMA-qPCR, with the highest levels of $2.14{\times}10^7copies/100ml$ in softener water, were much higher than the corresponding HPC results, which demonstrated the occurrence of numerous uncultured or VBNC bacteria among the entire system before reverse osmosis (RO). In addition, the microbial community structure was very different and the diversity was enhanced after the carbon filter. Although the diversity was minimized after RO treatment, pathogens such as Escherichia could still be detected in the RO effluent. In general, both the amounts of bacteria and the complexity of microbial community in the hemodialysis water treatment system revealed by molecular approaches were much higher than by traditional method. These results suggested the higher health risk potential for hemodialysis patients from the up-to-standard water. The treatment process could also be optimized, based on the results of this study.

• 한국환경과학회지
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• 제23권4호
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• pp.681-695
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• 2014

In a pilot-scale dyeing wastewater treatment using two-type fluidizing media, each thickness of biofilm was 15 and 30 ${\mu}m$, respectively. The numbers of protozoa inhabited in small-size (PEMT A) and big-size (PEMT B) media were $7.5{\times}10^4$ and $1.25{\times}10^5$ cells/ml, respectively, and dominant species were Entosiphon sulcatus var sulcatus in PEMT A and Chlamydomonas reinhardtii in PEMT B, respectively. Flask experiments using the two media revealed that the percentages of color removal were 25.8% in PEMT A and 27.1% in PEMT B after 72-h cultivation, indicating the necessity of bioaugmentation. Experiments for bioaugmentation effect on color removal were carried out in the pilot-scale treatment for 75 d by three-step operation under the control of wastewater loading rate and microbial input rate. Dye degradation occurred mainly in the second reaction tank, and the attachment of augmented dye-degrading microorganisms to media took at least 35 d. Final value of chromaticity in effluent was 227, meeting the required standard. Therefore bioaugmentation onto media was good for color treatment. In summary, thickness of biofilm formed on the media depended upon the size of media, resulting in different ecosystem inside the media. Hence, this affected microbial community and color treatment further. Accordingly, the reduction of operation cost is expected by efficient color-treatment process using bioaugmented media.

• Preventive Nutrition and Food Science
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• 제10권2호
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• pp.122-129
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• 2005

Chlorine dioxide $(ClO_2)$ treatment was evaluated for microbial growth inhibition and its effects on the quality of vacuum-packaged chicken breasts. Chicken breast samples were treated with 3, 50, and 100 ppm of $ClO_2$ solution, respectively. After $ClO_2$ treatment, chicken breast samples were individually vacuum-packaged and stored at $4^{\circ}C$, a typical storage temperature for meat and meat product, for 7 days. The vacuum-packaged chicken breasts treated with $ClO_2$ had significantly lower total bacteria, yeast and mold, total coliform, and Salmonella spp. were significantly reduced by $ClO_2$ treatment. $D_{10}-values$ of total bacteria count, yeast and mold, total coliform, and Salmonella spp. in vacuum-packaged chicken breasts was 93, 83, 85, and 50 ppm, respectively. The pH of vacuum-packaged chicken breasts decreased with increasing $ClO_2$ concentration. Thiobarbituric acid reacted substance (TBARS) values of vacuum-packaged chicken breasts increased during storage, regardless of $ClO_2$ concentration. $ClO_2$ treatment caused negligible changes in Hunter L, a, and b values in the vacuum-packaged chicken breasts. Sensory evaluation of the vacuum-packaged chicken breasts showed that there were no significant changes among the samples treated with various $ClO_2$ concentration. These results indicate that $ClO_2$ treatment could be useful in improving the microbial safety and quality of meat products.

• Preventive Nutrition and Food Science
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• 제12권3호
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• pp.181-184
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• 2007

Effect of aqueous chlorine dioxide ($ClO_{2}$) treatment on quality change of mackerel during storage was examined. Mackerel treated with 0, 5, 10, and 50 ppm of $ClO_{2}$ solution, respectively was stored at $4^{\circ}C$. $ClO_{2}$ treatment decreased populations of aerobic bacteria in mackerel during storage. The number of total aerobic bacteria of mackerel treated with 50 ppm $ClO_{2}$ increased from 2.45 to 3.44 log CFU/g after 9 days of storage, while that of the control increased from 3.47 to 4.72 log CFU/g. The pH values of mackerel increased during storage, with no significant changes among treatments. Volatile basic nitrogen values of mackerel were decreased by $ClO_{2}$ treatment. Quality of mackerel treated with $ClO_{2}$ was better than that of the control during storage based on sensory evaluation. These results indicate that aqueous $ClO_{2}$ treatment could be useful for improving the microbial safety and qualities of mackerel.

• Asian-Australasian Journal of Animal Sciences
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• 제19권1호
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• pp.109-112
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• 2006

The objective of this study was to evaluate the combined effects of lactoperoxidase system (LPS), thermal treatment and storage time on total microflora and psychrotrophs counts of the marinated broiler drumsticks. A marinade that contained acetic acid (1%) and salt (3%) with pH adjusted to 4 was developed as a standardized marinade. Drumsticks were marinated with various LPS levels, combined with thermal treatment (4 or $58^{\circ}C$ for 2 min), and then stored at $4^{\circ}C$ for 18 h. The microbial counts of the samples were measured after 0, 2, 4 and 7 days of storage for drumsticks held at $4^{\circ}C$. The results indicate that adding LPS at the level of 1 unit ($1{\mu}g/ml$ LP, 5.9 mM KSCN, and 2.5 mM $H_2O_2$) significantly (p<0.05) decreased the total microflora and psychrotrophs counts of the marinated broiler drumsticks. In addition, samples treated with a thermal treatment ($58^{\circ}C$ for 2 min) had significantly (p<0.05) lower microbial counts when compared with the control.

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1195-1206
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• 2020

Beringraja pulchra, Cham-hong-eo in Korean, is a mottled skate which is belonging to the cartilaginous fish. Although this species is economically valuable in South Korea as an alkaline-fermented food, there are few microbial studies on such fermentation. Here, we analyzed microbial changes and pH before, during, and after fermentation and examined the effect of inoculation by a skin microbiota mixture on the skate fermentation (control vs. treatment). To analyze microbial community, the V4 regions of bacterial 16S rRNA genes from the skates were amplified, sequenced and analyzed. During the skate fermentation, pH and total number of marine bacteria increased in both groups, while microbial diversity decreased after fermentation. Pseudomonas, which was predominant in the initial skate, declined by fermentation (Day 0: 11.39 ± 5.52%; Day 20: 0.61 ± 0.9%), while the abundance of Pseudoalteromonas increased dramatically (Day 0: 1.42 ± 0.41%; Day 20: 64.92 ± 24.15%). From our co-occurrence analysis, the Pseudoalteromonas was positively correlated with Aerococcaceae (r = 0.638) and Moraxella (r = 0.474), which also increased with fermentation, and negatively correlated with Pseudomonas (r = -0.847) during fermentation. There are no critically significant differences between control and treatment. These results revealed that the alkaline fermentation of skates dramatically changed the microbiota, but the initial inoculation by a skin microbiota mixture didn't show critical changes in the final microbial community. Our results extended understanding of microbial interactions and provided the new insights of microbial changes during alkaline fermentation.

• 한국식품저장유통학회지
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• 제18권1호
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• pp.98-102
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• 2011

본 연구에서는 이산화염소수를 이용한 계사 내 깔짚의 미생물 수 저감화를 통한 깔짚의 미생물학적 안전성 확보를 위하여 연구를 수행하였다. 사용하기 전의 깔짚에는 coliform, E. coli, Listeria spp., yeasts and molds 및 total aerobic bacteria가 높은 수준으로 검출되었으며 사용기간이 늘어남에 따라 미생물 수가 증가하였다. 500 ppm 이산화염소수를 이용한 살균처리에서는 coliform, E. coli, Listeria spp., yeasts and molds, total aerobic bacteria 및 Salmonella spp.의 균수가 모든 깔짚 시료에서 처리횟수에 따라 유의적으로 감소하였다. 사용하지 않은 깔짚에서는 coliform, E. coli, Listeria spp., yeasts and molds 및 total aerobic bacteria 수가 각각 4.47, 1.29, 1.23, 3.24 및 5.2 log CFU/g로 감소하였고, 1주 및 5주 사용한 깔짚의 경우도 모든 미생물 수가 현저하게 감소하였다. 따라서 본 연구 결과, 이산화염소수를 이용한 계사 내 깔짚의 미생물 수 저감화 방법이 도계된 계육의 미생물학적 안전성을 향상시키기 위한 방법으로 적합하다고 판단된다.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.324-329
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• 2004

Oxygen diffuses through the cation-specific membrane, reducing the coulomb yield of the fuel cell. In the present study, attempts were made to enhance current generation from the fuel cell by lowering the oxygen diffusion, including the uses of ferricyanide as a cathode mediator and of a platinum-coated graphite electrode. Ferricyanide did not act as a mediator as expected, but as an oxidant in the cathode compartment of the microbial fuel cell. The microbial fuel cell with platinum-coated graphite cathode generated a maximum current 3-4 times higher than the control fuel cell with graphite cathode, and the critical oxygen concentration of the former was 2.0 mg $1^{-1}$, whilst that of the latter was 6.6 mg $1^{-1}$. Based on these results, it was concluded that inexpensive electrodes are adequate for the construction of an economically feasible microbial fuel cell with better performance as a novel wastewater treatment process.