• Journal of the Korean Dietetic Association
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• v.25 no.1
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• pp.1-16
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• 2019

This study examined the microbiological quality of daycare center meals. Six menu items from five daycare centers in Daegu included uncooked processed foods (seasoned cucumber and lettuce salad), post-preparation after cooking processed foods (rolled omelet and seasoned soybean sprout), and cooking processed foods (panbroiled beef with oyster sauce and seasoned pork roast). Microbiological analyses were performed for the aerobic plate counts (APC), coliforms, and Escherichia coli. The analyses were conducted in July and November 2017. The mean APC and coliform count of seasoned cucumber decreased significantly from 4.71 log colony forming units (CFU)/g and 2.50 log CFU/g in July to 4.07 log CFU/g and 1.78 log CFU/g in November, respectively (P<0.01 and P<0.001). The APC of panbroiled beef with oyster sauce and seasoned pork roast were significantly lower in July (1.84 and 1.79 log CFU/g) than in November (2.41 and 2.28 log CFU/g) (P<0.001). The coliform counts of panbroiled beef with oyster sauce and seasoned pork roast were significantly greater in November (2.11 and 1.62 log CFU/g) (P<0.001). E. coli was not detected. Among the foods prepared using the three preparation processes, the post-preparation after cooking processed foods had the lowest microbial quality. The APC and coliform counts of cooking processed foods were satisfactory in July, with an acceptable rating for pan-broiled beef with oyster sauce in November. Time-temperature control and the prevention of cross-contamination are essential during meal production for food safety, regardless of the season.

• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.10-17
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• 2023

Dairy products are extensively used as carriers of probiotic strains that have potential health benefits. Assessment of the viability of probiotic strains during manufacturing is important to ensure that products meet recommended levels. Hence, the method for accurately quantifying lactic acid bacteria (LAB) in probiotic or dairy products is required. The present study aims to examine the performance of de-Man Rogosa Sharpe (MRS), plate count agar with bromocresol purple (PCA with BCP), and glucose blood liver (BL) agars recommended in the Korea Food Code guidelines for counting LAB. Analysis of the performance of culture media containing 19 lactic acid bacterial species commonly encountered in probiotic and dairy products showed no statistically significant difference between 18 reference strains and three culture media (p > 0.01). Furthermore, the suitability of three culture media was verified for the quantitative assessment of LAB in 25 probiotic and dairy products. The number of LAB in three culture media was determined to be more than 10⁷ colony-forming unit (CFU)/ml for fermented milk products and 10⁸ CFU/ml for condensed fermented milk and probiotic products, indicating that they all satisfied the Korea Food Code guidelines. Moreover, there was no statistically significant difference in the amount of LAB counted in all three culture media, suggesting that they can be used to isolate or enumerate LAB in commercial products. Finally, three culture media will be useful for isolating and enumerating LAB from fermented foods as well as gut microflora.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.4
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• pp.39-46
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• 2017

This paper presents the fabrication of ceramic insulation layer on metallic heat spreading substrate, i.e. an insulated metal substrate, for planar type heater. Aluminum alloy substrate is preferred as a heat spreading panel due to its high thermal conductivity, machinability and the light weight for the planar type heater which is used at the thermal treatment process of semiconductor device and display component manufacturing. An insulating layer made of ceramic dielectric film that is stable at high temperature has to be coated on the metallic substrate to form a heating element circuit. Two technical issues are raised at the forming of ceramic insulation layer on the metallic substrate; one is delamination and crack between metal and ceramic interface due to their large differences in thermal expansion coefficient, and the other is electrical breakdown due to intrinsic weakness in dielectric or structural defects. In this work, to overcome those problem, selected metal oxide buffer layers were introduced between metal and ceramic layer for mechanical matching, enhancing the adhesion strength, and multi-coating method was applied to improve the film quality and the dielectric breakdown property.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.9
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• pp.1340-1349
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• 2017

Objective: This study aimed to evaluate the microbiological and cellular milk profile for the diagnosis of subclinical mastitis in female buffaloes and to assess risk factors for predisposition of the disease. Methods: Analyses were carried out by standard plate count (SPC), identification of species and antibiotic resistance, somatic cell count (SCC), electrical electrical conductivity of milk (ECM), and lactoferrin content in milk. Teat cups were swabbed to evaluate risk factors, observing hyperkeratosis, milking vacuum pressure and cleanliness of the site. Hence, 30 female buffaloes were randomly selected (15 from a group in early lactation and 15 in late lactation). Results: The most common bacteria in the microbiological examination were Staphylococcus spp., Streptococcus spp. and Corynebacterium sp. In the antibiotic sensitivity test, 10 (58.82%) of the 17 antibiotics tested were sensitive to all isolates, and resistant bacteria were Streptococcus uberis, Streptococcus dysgalactiae, Streptococcus haemolyticus, and Escherichia coli. It was observed that positive samples in the microbiological examination showed total bacterial count between $9.10{\times}10^3$ to $6.94{\times}10^6$ colony forming units/mL, SCC between 42,000 to 4,320,000 cells/mL and ECM ranging from 1.85 to 7.40 mS/cm. It was also found that the teat cups had high microbial counts indicating poor hygiene, and even faults in the cleanliness of the animals' waiting room were observed. It is concluded that values of SCC above 537,000 cells/mL and ECM above 3.0 mS/mL are indications of mammary gland infection for this herd; however, the association of these values with a microbiological analysis is necessary to more accurately evaluate the health status of mammary glands with subclinical mastitis. Conclusion: Through phenotypic characterization of bacteria involved in the samples, the genera Staphylococcus spp., Streptococcus spp., and Corynebacterimum bovis were the most prevalent in this study. Faults in environment and equipment hygienization are factors that are directly associated with mastitis.

• Composites Research
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• v.31 no.3
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• pp.88-93
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• 2018

In this study, damaged composite laminates were repaired by a stepped patch repair method using halloysite nanotube(HNT) and milled carbon(MC) reinforced composite materials with different amount of the particles. And the mechanical and structural effects of the particles on the interface between the damaged and repair surfaces were analyzed. At this time, after exposing them to a harsh environment of high temperature and humidity for a long time, the recovery rate of the material properties relative to the material forming the damaged plate was compared. As a result, at $70^{\circ}C$ high temperature distilled water, the hygroscopicity of the HNT/GFRP composites was significantly different from that of the MC/GFRP composites. Especially, 0.5, 1 wt. % HNT was added, the moisture absorption rate was the lowest and this was the factor that contributed to the mechanical strength increase. On the other hand, MC showed a high hygroscopic resistance only with a small amount, and the strength was different according to the action direction of the load, and the addition amount was also different.

• Journal of Periodontal and Implant Science
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• v.39 no.3
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• pp.303-310
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• 2009

Purpose: The aerosol generated by ultrasonic scaler can contain bacteria or virus which can penetrate into body through respiratory systems of dentists, dental hygienist or patients. The aim of this study is to evaluate the effect of chlorhexidine digluconate as preoperative mouthrinse or lavage for ultrasonic scaler on the reduction of viable organisms in aerosol produced during periodontal treatment using ultrasonic scaler. Methods: 30 patients with moderate chronic periodontitis were included and divided into 3 groups: Control (no preoperative mouthrinse and tap water as lavage), CHG (preoperative mouthrinse with 0.1% chlorhexidine digluconate and tap water as lavage), CHL (no preoperative mouthrinse and 0.1% chlorhexidine digluconate as lavage). Each patient received scaling or subgingival curettage for 30 min. In CHG group, mouthrinse with chlorhexidine digluconate was performed for 1 min. before treatment. Before, during and after scaling or subgingival curettage, air sampling was performed for 7 min. each (1000 L/7 min.) with trypticase-soy agar plate. Agar plates were incubated in $37^{\circ}C$ aerobically. The numbers of colony-forming units (CFU) were counted and compared. Results: The numbers of CFUs of the samples obtained during treatment were $97{\pm}14.0$ in control, $73.1{\pm}14.9$ in CHG group and $44.5{\pm}9.0$ in CHL group. The difference among the 3 groups was determined to be statistically significant (one-way ANOVA with Bonferroni's correction, p-value: 0.0003). In contrast, the numbers of CFU of samples obtained before and after treatment were not significantly different among the groups. Conclusions: Chlorhexidine digluconate used as preoperative mouthrinse or lavage for ultrasonic scaler can reduce the microorganisms in aerosol produced during periodontal treatment using ultrasonic scaler. Less number of microorganisms were detected when chlorhexidine was used as lavage for ultrasonic scaler.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.110-117
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• 2009

To characterize plant root-associated bacteria in wild plant family Solanaceae, Solanum nigrum L. plants were collected in Dokdo island. Forty four strains of nitrogen-fixing or spore-forming bacteria were isolated from rhizosphere of Solanum nigrum L. plants. Among these, 19 strains were able to produce auxin. Thirteen strains of these produced siderophore as determined by color reaction on CAS-blue plate, 8 strains were able to solubilize phosphate. The 16S rDNA genes of the isolated bacteria were amplified and sequenced. Model plants, pepper and tobacco, were established in order to evaluate the bacterial capacities eliciting growth promotion and induced systemic resistance. The plants treated with strain KUDC1009 were more resistant and capable of growth-promotion than control plants when challenged by either Xanthomonas axonopodis pv. vesicatoria or Erwinia carotovora sub. carotovora strain SCC1. Rhizobacteria isolated from Dokdo island can promote growth of wild type Solanum nigrum L. under much environmental stresses.

• Korean Journal of Food Science and Technology
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• v.9 no.2
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• pp.97-105
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• 1977

1) In order to obtain a microbial strain having a strong yeast cell wall lytic activity, about 156 isolates capable of forming clear zones on baker's yeast-peptone-bouillon agar plate were obtained from soil, mud and water samples and a strain K-42 with the highest lytic activity was identified as Bacillus circulans. 2) Effect of carbon sources on the lytic enzyme production by the K-42 strain was in the decreasing order of maltose>glucan>xylose>control in 2-day culture and of lactose>galactose>glucan>control in 3-day culture. Effect of inorganic nitrogen sources was in the decreasing order of ammonium acetate>sodium nitrate>control in 2-day culture and of ammonium chloride>ammonium oxalate>control in 3-day culture, whereas organic nitrogen sources except milk casein showed an increase in 2-day culture and a decrease in 3-day culture. Synergistic effect of carbon sources and nitrogen sources was not observed. 3) The enzyme production by the K-42 strain was greatly affected by pH change of the culture medium, thus a high lytic activity could be maintained by keeping the pH range of $7{\sim}8$ and adding carbon or nitrogen sources. 4) Optimum conditions for the lytic activity of the K-42 strain were obtained at $pH\;7{\sim}8$ and $60^{\circ}C$ and the extent of hydrolysis toward heated yeast cell wall was 65%.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.541-545
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• 2007

The potential to produce biogenic amines was investigated in microbial strains isolated from fermented soybean paste, cheonggukjang. The typical levels of 11 biogenic amines, including putrescine, histamine, and tryptamine, were analyzed in commercial cheonggukjang. The tyramine and histamine levels in the samples ranged from 4.2 to 483.1 mg $kg^{-1}$ and 0.2 to $70.3mg\;kg^{-l}$, respectively. A total of 4 microbial strains of Bacillus sp. were isolated from cheonggukjang. The Bacillus sp. were identified as B. amyloliquefaciens, B. subtilis, and B. licheniformis based on phenotypic characteristics, which included using the VITEK system. The screening plate method for detecting amino acid decarboxylase positive microorganisms was performed. The results fer amino decarboxylation were positive, and biogenic amine formation was evaluated by the confirmation of amine-forming capacity.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1530-1530
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• 2001

The objectives of this study were to develop models to predict quality parameters of Korean bee-honeys by visible and NIR spectroscopic technique. Two kinds of bee-honey fronl acacia and polyflower sources were tested in this study. The honeys were harvested in the spring of 2000 and stored in the storage facility at 20$^{\circ}C$ during experiments. Total of 394 samples of honey were analyzed. Reflectance spectra, moisture contents, ash, invert sugar, sucrose, F/G (fructose/glucose) ratio, HMF (hydroxymethyl furfural), and C12/C13 ratio of honeys were measured. The average values for the tested honeys were 19.9% of moisture contents, 0.12% of ash, 68.4% of invert sugar, 5.7% of sucrose, 1.27 of F/G(fructose/glucose) ratio, 14.4 mg/kg of HMF, and -19.1 of C12/C13 ratio. A spectrophotometer, equipped with a single-beam scanning monochromator (NIR Systems, Model 6500, USA) and a horizontal setup module, was used to collect reflectance data from honey. The reflectance spectra were measured in wavelength ranges of 400∼2,498 nm. with 2 nm of interval. Thirty-two repetitive scans were averaged, transformed to log(1/Reflectance), and then were stored in a microcomputer file, forming one spectrum per measurement. A sample cell and reflectance plate were made to hold honey samples constantly. Spectra of honey samples were divided into a calibration set and a validation set. The calibration set was used during model development, and the validation set was used to predict quality parameters from unknown spectra. The PLS(Partial Least Square) models were developed to predict the quality parameters of honeys. The first and the second derivatives of raw spectra were also used to develop the models with proper smoothing gap. The MSC (multiplicative scatter correction) and the SNV & Dtr.(standard normal variate and detranding) preprocessing were applied to all spectra to minimize sample-to-sample light scatter differences. The PLS models showed good relationships between predicted and measured quality parameters of honeys in the wavelength range of 1100∼2200 nm. However, the PLS analysis was not good enough to predict HMF of honeys.