• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.151-160
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• 1998

The Leuconostoc paramesenteroides dominated at refrigeration temperature range was isolated from kimchi, and improved its growth properties by mutation for competitive growth against Lactobacillus plantarum at lower pH. It was found that the minimal pH for the wild type Leuconostoc paramesenteroides Pw growth was pH 4.5 adjusted with HCI and pH 5.0 adjusted with organic-mixture (lactic acid:acetic acid=1:2), respectively. The mutant P-100 could grow in pH 4.0, 4.5, respectively, in MRS broth. Two strains Pw and P-100 were added into kimchi as starter and compared the quality characteristics of kimchi. The total acceptability of Pw and P-100 inoculated kimchi were evaluated better than that of control kimchi (no starter added) by sensory test and extended the optimal pH range of kimchi up to about 2.2, 2.5 times, respectively. In kimchi added P-100, the succinic acid was more abundant than others and the total number of Lactobacillus plantarum was down about 2.5 times in contrast to control kimchi.

• The Journal of Korean Medicine
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• v.37 no.1
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• pp.21-33
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• 2016

This study aimed to investigate the stability and biological activities of BHSST decoction depending on the preservation temperature and periods. Methods: BHSST decoction was preserved at room temperatures (R/T, $23{\pm}1^{\circ}C$) or refrigeration ($4^{\circ}C$) for 0, 30, 60 and 90 days. To evaluate the stability of BHSST decoction, pH and sugar content were estimated. In addition, high-performance liquid chromatography (HPLC) analysis was performed to determine marker compounds of BHSST decoction. To evaluate anti-inflammatory effect, nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) productions were measured in LPS-stimulated RAW 264.7 macrophages. Antioxidant activity was examined using the assays for 3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) and 1-1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities. Results: There was no change in pH and sugar content depending on the preservation temperature and periods of BHSST decoction. Among the major components of BHSST, contents of liquiritin, baicalein and wogonin was reduced time-dependently both at R/T and $4^{\circ}C$. Inhibitory effects of BHSST decoction on NO and PGE2 productions were slightly decreased in a time-dependent manner by 90 days of preservation. In addition, BHSST decoction maintained ABTS and DPPH radical scavenging activities by 60 days while significantly reducing the activities in 90 days of preservation at R/T. By contrast, BHSST decoction had no significant change of ABTS and DPPH radical scavenging activities by 90 days at $4^{\circ}C$. Conclusions: Our results suggest that the stability and efficacy of BHSST decoction are maintained for 60 days at $4^{\circ}C$ rather than R/T.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.3
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• pp.185-190
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• 1987

In order to study the preservation effect of $-3^{\circ}C$ partial freezing method, tile growth and biochemical activity of microorganisms and the changes of K-value in mackerel press juice were investigated at $0^{\circ}C,\;-3^{\circ}C$ supercooling (liquid phase) and $-3^{\circ}C$ freezing (solid phase). The results obtained in this paper were follows : 1) The growth and biochemical activity of microorganisms were reduced at $-3^{\circ}C$ supercooling than $0^{\circ}C$ in spite of the small variation in temperature. 2) There were no growth and biochemical activity of microorganisms at $-3^{\circ}C$ freezing (solid phase). 3) The difference in the K-value between $-3^{\circ}C$ supercooling and $-3^{\circ}C$ freezing was remarkable in spite of the same temperature.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.208-223
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• 1994

The purpose of this study was to evaluate the efficiency of diffusive(or passive) sampler in measuring airbone organic solvents. Diffusive samplers are generally simple in construction and do not require power for operation. The efficiency of the diffusive samplers has not sufficiently been investigated in Korea. Three types of samplers were studied in this study. The sampling and analytical results by passive samplers were compared with results by charcoal tube method recommended by NIOSH(National Institute for Occupational Safty and Health). The following characteristics are identified and studied as critical to the performance passive monitors; recovery, reverse diffusion, storage stability, accuracy and precision, face velocity and humidity, n-Hexane, TCE(trichloroethylene) and toluene were used as test vapors. A dynamic vapor exposure system consisting of organic vapor generator and sampling chamber for evaluating diffusive samplers are made. The results of the study are summarized as follows. 1. NIOSH recommands that the overall accuracy of a sampling method in the range of 0.5 to 2.0 times the occupational health standard should be ${\pm}25$ percent for 95 percent confidence level. Among three types of diffusive samplers, sampler A has permeation membrane and samplers Band C have diffusive areas, samplers A and B met the criterion that overall accuracy for 95% confidence level of the samplers were within ${\pm}25$ percent of the reference value. Sampler C had overall accuracy ${\pm}9.6%$ and ${\pm}11.8%$ in hexane and TCE, respectively. The concentration of toluene was overestimated in sampler C with overall accuracy of ${\pm}43.9%$. 2. The desorption efficiencies of diffusive samplers were 96-107%. 3. There was no significant sampe loss during four weeks of storage both with and without refrigeration. 4. There was no significant reverse diffusion, when the samplers were exposure to clean air for 2 hours after sampling for 2 hours at the level of 2 TLY. 5. In case of 8 hours sampling, relative differences(RD) of concentrations between charcoal tube method and diffusive method were 15-39%, 13-46%, and 4-35% for sampler A, B and C, respectively. The performance was poor in 8 hours sampling for multiple substance monitors. 6. At high velocity(100 cm/sec), samplers B and C overestimated the concentrations of organic vapors, and sampler A with permeation membrance gave better results. 7. At 80% relative humidity, samplers showed no siginificant effect. Low humidity also did not affect the diffusive samplers.

• Journal of Nutrition and Health
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• v.12 no.1
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• pp.51-58
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• 1979

It is a general trend everywhere that the uses of vegetable oils are increasing due to the fact that they are effective in curing and preventing symptoms of high blood pressure and various heart failure conditions. At the same time the concept that oxidative rancidity is caused by the oxidation of unsaturated fatty acid moieties whose subsequent decomposition gives rise to various undesirable, sometimes toxic compounds is now well accepted. Linolenic acid (C, 18:3) is one of highly unsaturated and readily oxidizable fatty acid. The content of this essential polyunsaturated fatty acid in perilla seed oil (PSO) was found to be as high as 48% while only 1.5% in sesame seed oil (SSO). In this experiment the oxidative stability of PSO was compared with that of SSO. The experimental test group were as follows: A) Stored at different temperatures, namely $4^{\circ}C,\;30^{\circ}C,$ and $60^{\circ}C,$ B) Stored at room temperature $(20{\pm}5^{\circ}C)$ ; a. protected from sunlight and air, b. exposed to air without sunlight c. exposed to sunlight but protected front air, d. completely exposed to both air and sunlight. The following results were obtained; 1) It was found to be most stable against oxidation to store both PSO and SSO under the low temperature $(4^{\circ}C)$ condition. According to P.V. measurements it was found to be safe to keep both oils up to $30^{\circ}C$ for at least 8 weeks. When exposed to air, sunlight and high temperature $(60^{\circ}C)$, P.V. of PSO reached there peak values, which were much higher than those of SSO. This explains much of its instability as compared to SSO against oxidation. 2) The effect of high temperature $(60^{\circ}C)$ on A.V. was found to be more striking than those of all the other storage conditions. The condition of refrigeration was most effective in keeping A.V. low for both oils as was the case in P.V. 3) For both oils, I.V. decreased throughout the experimental period (8 weeks). The range of decrement was larger for PSO than SSO. 4) There was no significant change in the compositions of fatty acids of SSO caused by various experimental storage conditions. But for PSO the compositions of stearic, oleic and linoleic acid were decreased, whereas linolenic acid was increased proportionally.

• The Korean Journal of Food And Nutrition
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• v.25 no.2
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• pp.291-298
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• 2012

One of the main microorganisms causing diarrheal diseases is Campylobacter jejuni. Purslane or Portulaca oleracea is an edible plant containing polyphenols that has been widely used as a folk remedy for treatment of diarrhea for a long time. This study was performed to investigate the antimicrobial activity of fermented P. oleracea extracts made with probiotics and plant-origin lactic acid bacteria(PLAB) isolated from P. oleracea against C. jejuni. Lactobacillus rhamnosus, L. acidophilus, L. bulgaricus, L. delbrueckii, L. plantarum, Leuconostoc mesenteroides and Bifidobacterium longum were applied to P. oleracea to make a fermentation broth of purslane. Leuconostoc mesenteroides and the lactic acid bacteria isolated from P. oleracea grew best in the fermentation broth of P. oleracea extracts when the broth was combined with 2% yeast extract, 1% peptone, and 0.05 to 1% potassium phosphate. The number of viable cells in the fermentation broth containing purslane extracts after 48 hours increased to $1{\times}10^{12}\;CFU/m{\ell}$ and remained at $1.3{\times}10^{10}\;CFU/m{\ell}$ after refrigeration for 2 weeks. The pH and acidity of purslane-fermented broth after 48 hours of fermentation was 3.7 and 3.14, respectively, which show that the fermentation broth was within the range of the general standards of fermented dairy products. The antimicrobial activity of the fermented P. oleracea extracts was determined using the liquid culture method. The 10 $mg/m{\ell}$ concentration of the fermented P. oleracea extract made with Leuconostoc mesenteroides and the lactic acid bacteria isolated from purslane showed the strongest antimicrobial activity against C. jejuni. The fermentation broth of purslane with the probiotics retarded the growth of C. jejuni for 48 hours at $42^{\circ}C$.

• Food Science and Preservation
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• v.24 no.5
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• pp.593-599
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• 2017

The objective of this study was to investigate the effect of superheated steam (SHS) and high hydrostatic pressure (HHP) techniques on the improvement of the quality of Bulgogi product during manufacturing process. Bulgogi product was treated with four different cooking/treatment process: conventional cooking (CC), SHS cooking (SHS), CC and then HHP cooking (CC-HHP), and SHS and HHP cooking (SHS-HHP) samples. SHS treated product increased moisture content, and decreased crude protein. Additionally, hardness, gumminess and shear force values were significantly different among the samples (p<0.05). In safety experiment after 14 days of storage at refrigeration temperature indicated that the bacterial population was lower in the case of SHS-HHP as compared to CC-HHP. Changes in texture during the storage periods at $10^{\circ}C$ for SHS-HHP was lowest values with compared to the initial, while shear force values for both tended to decrease with increasing storage period. The TBA and VBN values for SHS-HHP increased to 0.48 ($5^{\circ}C$)-1.68 ($10^{\circ}C$) mg MD/kg and 25.14 ($5^{\circ}C$)-45.14 ($10^{\circ}C$) mg%, respectively after 15 days of storage. Overall, it was found that the combination of SHS and HHP reduced microbial growth, thus leading to improved product quality and sanitation.

• Journal of Food Hygiene and Safety
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• v.23 no.3
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• pp.227-232
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• 2008

The purpose of this study was to investigate the antibacterial effect of films on shelf-life and microbiological Safety of pork meat. Effects of antimicrobial films against total aerobic bacteria, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, Staphylococcus aureus in pork meat were evaluated during storage of 14 days at $5^{\circ}C,\;10^{\circ}C\;and\;15^{\circ}C$. Antimicrobial films were developed with addition of a natural substance, wasabi extracts(Wasabia japonica). At $5^{\circ}C$ storage, growth of total aerobic bacteria, E. coli O157:H7, L. monocytogenes were inhibited higher than at 10 and $15^{\circ}C$. Especially, the numbers of S. Typhimurium and S. aureus were increased gradually at $5^{\circ}C$ even in the control sample, and it takes more than 14 days to increase in every sample upto 6 $log_{10}cfu/g$. The higher antimicrobial effects of the films were observed at storage of $5^{\circ}C$ than at $10^{\circ}C$ and $15^{\circ}C$. There was a limit of a single treatment of antimicrobial film to prolong shelf-life of pork meat. The synergistic effect of antimicrobial film were observed with addition of refrigeration at $5^{\circ}C$.

• Applied Biological Chemistry
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• v.13 no.3
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• pp.207-218
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• 1970

Studies were carried out to develope the most economical and practical methods of packaging and preservation of kimchi, so commercialization of kimchi manufacture could proceed rapidly. The results obtained may be summarized as following. (1) It is generally established that the acceptable range of lactic acid content of kimchi is between 0.4% and 0.75%. Based on sensory evaluation, kimchi having lactic acid content below 0.4% and above 0.75% was not edible, and the time of optimum taste corresponded to the vicinity of 0.5% of lactic acid content. For the refrigeration storage with or without preservatives, the packaging kimchi in plastic film must be done at the lactic acid content of 0.45%, for lactic acid fermentation will continue slowly after the packaging. However, for the heat sterilized kimchi the packaging should be done at the 0.5% of lactic acid content for the best because lactic acid fermentation is completely stopped after the packaging. (2) Polyethylene, polypropylene, and polycello were chosen as suitable packaging materials. Polyethylene is cheapest among them but kimchi packaged in this film was damaged frequently in handling process and gave off kimchi flavor. On the other hand polypropylene also gave off kimchi flavor, but its higher mechanical strength gave better protection to kimchi and it had superior display effect due to the transparancy. Therefore polypropylene made much better packaging material. Polycello proved to be the best packaging material from the standpoint of physical characteristics but its price is higher than that of other plastic films. To be effective, the thickness of plastic films for packaging kimchi must exceed 0.08mm. (3) Keeping property of kimchi appeared to be excellent by means of freezing. However, by the time the frozen kimchi was thawed out at room temperature, moisture loss due to drip was extensive, rendering the kimchi too stringy. (4) Preservation of kimchi at refrigerated temperatures proved to be the best method and under the refrigerated condition the kimchi remained fresh as long as 3 months. The best results were obtained when kimchi was held at $0^{\circ}C$. (5) In general, preservatives alone were not too elective in preserving kimchi. Among them potassium sorbate appeared to be most effective with the four fold extension of self-life at $20^{\circ}C$ and two fold extension at $30^{\circ}C$. (6) In heat sterilization the thickness of packaged kimchi product had a geat effect upon the rate of heat penetration. When the thickness ranged from 1.5 to 1.8cm, the kimchi in such package could be sterilized at $65^{\circ}C$ for 20 minutes. Kimchi so heat treated could be kept at room temperature as long as one month without apparent changes in quality. (7) Among combination methods, preservation at refrigerated and heat sterilization could be favorably combined. When kimchi was stored at $4^{\circ}C$ after being sterilized at $65^{\circ}C$ for 20 minutes, it was possible to preserve the kimchi for more than 4 months.

• Journal of Bio-Environment Control
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• v.26 no.4
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• pp.317-323
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• 2017

In this study, the heating performance and the energy saving effect of the heat pump system using hot waste water(waste heat) of the thermal power plant discharged from a thermal power plant to the sea were analyzed. The greenhouse area was $5,280m^2$ and scale of the heat pump system was 120 RT(Refrigeration Ton), which was divided into 30 RT, 40 RT and 50 RT. The heat pump system consisted of the roll type heat exchangers, hot waste water transfer pipes, heat pumps(30, 40, 50 RT), a heat storage tank and fan coil units. The roll type heat exchangers was made of PE(Poly Ethylene) pipes in consideration of low cost and durability against corrosion, because hot waste water(sea water) is highly corrosive. And the heating period was 5 months from October to February. During the heating performance test(12 hours), the inlet water temperature of evaporator was changed from $32^{\circ}C$ to $26^{\circ}C$, and heat absorption of he evaporator was changed from 175 kW to 120 kW. The inlet water temperature of the condenser rose linearly from $15^{\circ}C$ to $50^{\circ}C$, and the heat release of condenser was reduced by 40 kW from 200 kW to 160 kW. And the power consumption of the heat pump system increased from 30 kW to 42 kW. When the inlet water temperature of condenser was $15^{\circ}C$, the heating COP(Coefficient Of Performance) was over 7.0. When it was $30^{\circ}C$, it dropped to 5.0, and when it was above $40^{\circ}C$, it decreased to less than 4.0. It was analyzed that the reduction of heating energy cost was 87% when compared to the duty free diesel that the carbon dioxide emission reduction effect was 62% by recycling the waste heat of the thermal power plant as a heat source of the heat pump system.