• Culinary science and hospitality research
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• v.14 no.3
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• pp.136-142
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• 2008

This study was conducted to investigate the correlation of the physicochemical quality index(pH, acidity, reducing sugar content and lactic acid bacterial count) and sensory index(sourness) of Kakdugi during the fermentation at 5$^{\circ}C$, 10$^{\circ}C$ and 20$^{\circ}C$ respectively. Also, the relations between physicochemical quality index and overall acceptability were carried out. The pH range, based on the middle sour intensity point of 4.5, was 5.75 at 5$^{\circ}C$ fermentation, whereas that was 4.2 at 10$^{\circ}C$ and 20$^{\circ}C$ fermentation. The pH showing the highest overall acceptability decreased along with increased fermentation temperature. The reduced sugar content decreased rapidly up to 0.9% acidity, but after that, decreased slowly from more than 0.9% acidity at all fermentation temperatures. With increased fermentation temperature, the reduced sugar content showing the highest overall acceptability also showed the decreasing tendency. Change patterns of lactic acid bacterial count and sourness didn't coincided at 5$^{\circ}C$ fermentation, whereas those did at 10$^{\circ}C$ and 20$^{\circ}C$ fermentation. The indexes showing high significant correlations with sourness of Kakdugi fermented at 5$^{\circ}C$ were not pH and lactic acid bacterial count but acidity and reducing sugar content(p<0.05). The sourness of Kakdugi fermented at 10$^{\circ}C$ and 20$^{\circ}C$ showed high significant correlations with all of the physicochemical index(p<0.05).

• Microbiology and Biotechnology Letters
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• v.42 no.2
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• pp.121-130
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• 2014

Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis was adopted to explore rapid differentiation in the diversity and dynamics of bacteria in kimchi made in Korea and China for future application in kimchi origin discrimination. T-RFLP analysis supported the reproducible and rapid detection of major lactic acid bacteria known to be involved in kimchi fermentation. The taxonomic resolution level of this T-RFLP analysis was between the species and genus level, but was not specific enough for the detection of a bacterium found only in one origin, either Korea or China. The bacterial community structure successions in kimchi samples from Korea and China analyzed by T-RFLP analysis occurred with a similar pattern. Bacillus spp. which were not detected in the early microbial studies of kimchi were constantly detected until the late fermentation stage of kimchi in our T-RFLP analysis and their existence was proved by culture-based identification. Additionally, sporulation of Bacillus spp. during kimchi fermentation was discovered.

• Animal Bioscience
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• v.37 no.2_spc
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• pp.337-345
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• 2024

Ruminants possess a specialized four-compartment forestomach, consisting of the reticulum, rumen, omasum, and abomasum. The rumen, the primary fermentative chamber, harbours a dynamic ecosystem comprising bacteria, protozoa, fungi, archaea, and bacteriophages. These microorganisms engage in diverse ecological interactions within the rumen microbiome, primarily benefiting the host animal by deriving energy from plant material breakdown. These interactions encompass symbiosis, such as mutualism and commensalism, as well as parasitism, predation, and competition. These ecological interactions are dependent on many factors, including the production of diverse molecules, such as those involved in quorum sensing (QS). QS is a density-dependent signalling mechanism involving the release of autoinducer (AIs) compounds, when cell density increases AIs bind to receptors causing the altered expression of certain genes. These AIs are classified as mainly being N-acyl-homoserine lactones (AHL; commonly used by Gram-negative bacteria) or autoinducer-2 based systems (AI-2; used by Gram-positive and Gram-negative bacteria); although other less common AI systems exist. Most of our understanding of QS at a gene-level comes from pure culture in vitro studies using bacterial pathogens, with much being unknown on a commensal bacterial and ecosystem level, especially in the context of the rumen microbiome. A small number of studies have explored QS in the rumen using 'omic' technologies, revealing a prevalence of AI-2 QS systems among rumen bacteria. Nevertheless, the implications of these signalling systems on gene regulation, rumen ecology, and ruminant characteristics are largely uncharted territory. Metatranscriptome data tracking the colonization of perennial ryegrass by rumen microbes suggest that these chemicals may influence transitions in bacterial diversity during colonization. The likelihood of undiscovered chemicals within the rumen microbial arsenal is high, with the identified chemicals representing only the tip of the iceberg. A comprehensive grasp of rumen microbial chemical signalling is crucial for addressing the challenges of food security and climate targets.

• The Korean Journal of Food And Nutrition
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• v.20 no.4
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• pp.363-368
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• 2007

Traditional kochujang samples were collected from the folk village in Sunchang to find the major microbial composition and correlation between the taste and the microbial properties. Among the 29 samples, 17 samples showed Bacillus licheniformis as dominant strain with 11 samples Bacillus subtilis and 1 sample Staphylococcus pasteuri. Subdominant strain of 17 samples was Bacillus licheniformis with 12 samples Bacillus subtilis. Dominant strain numbers varied in rage of $6.60{\sim}8.38$ logCFU/g with subdominant strain number $5.90{\sim}7.86$ logCFU/g and total microbial number $6.64{\sim}8.56$ logCFU/g respectively. Bacterial type number varied in range of $6{\sim}18$ with the average 10.5 types. Fungi were found only in 2 samples and identified all to be Aspergillus oryzae. Yeasts were found in 25 samples. The dominant yeast strain of 23 samples was identified to be Zygosaccharomyces pseudorouxii and that of 2 samples Zygosaccharomyces rouxii. Yeast type variety showed that only single type was found in 15 samples, 2 types in 8 samples, 3 types in 1 sample and 4 types in 1 sample. Fungal number was 3.90 and 4.08 logCFU/g and yeast numbers varied in range of $3.90{\sim}6.43$ logCFU/g. The sensory scores of kochujang showed positive correlation with type numbers, but no significant correlation with the other microbial properties like total bacterial number, dominant bacterial number, subdominant bacterial number and dominant yeast number.

• Food Science of Animal Resources
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• v.35 no.1
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• pp.143-148
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• 2015

Yogurt powder is fermented milk processed in the form of dry yogurt, and has advantages such as stability, storability, convenience, and portability. China and Vietnam are important export target countries because of the increased demand for dairy products. Therefore, we surveyed dairy product standardization in order to establish an export strategy. Lactic acid bacteria counts are unregulated in Korea and Vietnam. In China, lactic acid bacteria counts are regulated at $1{\times}10^6$ colonyforming units (CFU)/mL and detected at $6.24{\pm}0.33\;Log\;CFU/mL$. All three countries have regulated standards for total bacterial counts. In China, total bacterial counts of milk powder are regulated to n=5, c=2, m=50,000, M=200,000 and detected at $6.02{\pm}0.12\;Log\;CFU/mL$, exceeding the acceptable level. Lactic acid bacterial counts appeared to exceed total bacterial counts. Coliform group counts, Staphylococcus aureus, Listeria monocytogenes, and Salmonella species were not detected. Acidity is not regulated in Korea and Vietnam. In China, acidity was regulated to over $70^{\circ}T$ and detected $352.38{\pm}10.24^{\circ}T$. pH is unregulated in all three countries. pH was compared to that of general fermented milk, which is 4.2, and that of the sample was $4.28{\pm}0.01$. Aflatoxin levels are not regulated in Korea and China. In Vietnam, aflatoxin level is regulated at 0.05 ppb. Therefore, all ingredients of the yogurt powder met the safety standards. This data obtained in this study can be used as the basic data in assessing the export quality of yogurt powder.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.262-267
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• 2014

To analyze the presence of microbes in organic farm produce, green chillies, lettuce, tomatoes, apples, pears, and rice were collected at 47 production sites with organic and conventional produce. Total average bacterial counts of 4.07 log CFU/g in organic green chillies, 3.71 log CFU/g in conventional green chillies, and 6.76- 6.90 log CFU/g in the both lettuce were detected. Mean bacterial counts of 4.48 log CFU/g and 2.84 log CFU/g were detected in organic and conventional pear produce, respectively. Differences in bacterial counts in tomatoes, apples, and rice in organic and conventional produce were less pronounced. Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and Staphylococcus aureus were not detected in any produce sample. However, Bacillus cereus was detected with average counts of 1.04 log CFU/g in 11/47 (23%) conventional produce samples and 1.97 log CFU/g in 6/47 (13%) organic produce samples. Therefore, organic and conventional produce showed similar microbial prevalence patterns, and comparable safety in terms of pathogen contamination.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.209-221
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• 2019

In this study, the changes in microbial communities of lamb meat packaged in the air (plastic tray, PT) and in a vacuum pouch (VAC) were assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) during the storage at $4^{\circ}C$. For the PT lamb, the total viable count (TVC) was $10^7CFU/g$ on Day 5, and the dominated bacteria were Pseudomonas fragi, P. fluorescens, and Acinetobacter spp. For the VAC lamb, the TVC was $10^7CFU/g$ on Day 9, and the dominated bacteria were lactic acid bacteria, including Carnobacterium divergens, C. maltaromaticum, and Lactococcus piscium. One strain of Pseudomonas spp. also appeared in VAC lamb. The relative abundance of Enterobacteriaceae in VAC lamb was higher than that PT lamb, indicating a more important role of Enterobacteriaceae in spoilage for VAC lamb than that of PT lamb. The microbial compositions changed faster in the lamb stored in a PT than that stored in a VAC, and microbial community compositions of the late storage period were largely different from those of the early storage period for both the conditions. The findings of this study may guide improve the lamb hygiene and prolong the shelf life of the lamb.

• Journal of Microbiology and Biotechnology
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• v.18 no.10
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• pp.1678-1682
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• 2008

To investigate lactic acid bacterial population in Korean traditional rice wines, biotyping was performed using cell morphology and whole-cell protein pattern analysis by SDS-PAGE, and then the isolates were identified by 16S rRNA sequencing analysis. Based on the morphological characteristics, 103 LAB isolates were detected in wine samples, characterized by whole-cell protein pattern analysis, and they were then divided into 18 patterns. By 16S rRNA gene sequencing, the isolates were identified as Lactobacillus paracasei, Lb. arizonensis, Lb. plantarum, Lb. harbinensis, Lb. parabuchneri, Lb. brevis, and Lb. hilgardii when listed by their frequency of occurrence. It was found that the difference in bacterial diversity between rice and grape wines depends on the raw materials, especially the com position of starch and glucose.

• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1653-1659
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• 2015

Epothilone, which is produced by the myxobacterium Sorangium cellulosum, contributes significant value in medicinal development. However, under submerged culture conditions, S. cellulosum will accumulate to form bacterial clumps, which hinder nutrient and metabolite transportation. Therefore, the production of epothilone by liquid fermentation is limited. In this study, diatomite-based porous ceramics were made from diatomite, paraffin, and poremaking agent (saw dust). Appropriate methods to modify the porous ceramics were also identified. After optimizing the preparation and modification conditions, we determined the optimal prescription to prepare high-performance porous ceramics. The structure of porous ceramics can provide a solid surface area where S. cellulosum can grow and metabolize to prevent the formation of bacterial clumps. S. cellulosum cells that do not form clumps will change their erratic metabolic behavior under submerged culture conditions. As a result, the unstable production of epothilone by this strain can be changed in the fermentation process, and the purpose of increasing epothilone production can be achieved. After 8 days of fermentation under optimized conditions, the epothilone yield reached 90.2 mg/l, which was increased four times compared with the fermentation without porous ceramics.

• The Korean Journal of Food And Nutrition
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• v.32 no.6
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• pp.701-710
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• 2019

This study investigated the effect of apios powder on the quality characteristics of sausages. The results were as follows: pH values of the sausages were not significantly different among the samples. The amount of moisture content in the sausages decreased with increasing amount of apios powder. Increase in apios powder increased the lightness (L) value but decreased redness (a) and yellowness (b) values. Increase in apios powder increased the hardness and chewiness of sausage but decreased the adhesiveness. Apios powder had no significant effect on gumminess and springiness of the sausages among all samples. Total phenolic compound content and DPPH radical scavenging activity of apios powder added sausage significantly increased with increasing apios powder. Total bacterial counts of apios powder added sausage increased in all the samples as storage period passes and after 4 weeks of storage, the more adding ratio of apios powder was increased, the total bacterial count decreased. In view of above results, apios powder was considered to be food material suitable not only for functionality but also for developing sausage product of which preservation property is improved. From the results, 100% apios powder can be used to make optimum level for production of sausage.