• Korean Journal of Microbiology
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• v.28 no.1
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• pp.71-75
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• 1990

The isolates biodigrading crude oil were examined to characterize thier properties. Isolates which were identified as Acinetobacter lwoffii G1, Klebsiella pneumoniae L25, Pseudomonas maltophilia N246, Xanthomonas campestris M12, and Xanthomonas sp. M28. The optimum concentration of crude oil was 0.15% for the bacterial growth. X. campestris M12, Xanthomonas sp. M28, and K. penumoniae L25 showed the maximal growth at the concentration of 3.5% sodium chloride, indicating that they were derived from sea water. Among the isolates, X. campestris M12, Xanthomonas sp. M28 specially utilized hexadecane and octane, and P. maltophilia N246 utilized octane with optimum concentration of 0.2-0.3% as sole carbon source. The utilization of components of saturate fraction by K. pneumoniae L25 was examined by gas-liquid chromatography. The short-chain saturates are used before the long chain ones although they almost disappear within 8 days of incubation at $30^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.3
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• pp.435-446
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• 2012

The present study identified volatile flavor components of Hanwoo longissimus muscle and other Korean foods (Doenjang, Chungukjang, sesame oil) and their traits were compared in relation with flavor precursors that include fatty acids and protein degradation products. Hanwoo longissimus muscle was purchased from a commercial abattoir while the other foods were sampled from three separate households. The results showed totals of 68 ($9.94{\mu}g/g$), 60 ($15.75{\mu}g/g$), 49 ($107.61{\mu}g/ml$) and 50 ($7.20{\mu}g/g$) volatile components for Doenjang, Chungukjang, sesame oil and Hanwoo beef longissimus, respectively (p<0.05). Aldehydes were the most predominant components in beef, but alcohols, acids and esters, and pyrazines are probably the major contributors to the flavor characteristics of other foods. SDS-PAGE revealed that beef longissimus muscle and Doenjang showed higher protein degradation than other foods which could be likely related to chiller ageing and ripening process. The total polyunsaturated fatty acids were approximately 50, 60, 41 and 5% for Doenjang, Chungukjang, sesame oil and beef longissimus muscle, respectively. Based on the mechanism(s) of generation of the volatile compounds and the chemical composition of each food sample, differences and traits of volatile flavor components among the four food types are likely due to fatty acid profiles, proteolytic activity and processing conditions. Aroma intense compounds like pyrazines and sulfur-containing compounds were limited in cooked beef in the current experimental condition (i.e., relatively low heating temperature). This suggests that higher heating temperature as in the case of roasting is needed for the generation of high aroma notes in meat. Furthermore, proteolytic activity and stability of fatty acids during ageing have a great influence on the generation of flavor components in cooked beef.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.435-438
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• 2000

Crude oil-degrading microorganisms, Acinetobacter sp. A132, Pseudomonas aeruginosa F722, and Acinetobacter calcoaceticus OM1 were isolated from soil and sea. The optimal temperature of strain A132 and strain F722 on growth isolated from soil was $35^{\circ}C$ both, and also their growth were optimized at pH 8 and 9, respectively. The growth of the strains, A132 and F722, showed that crude oil of 2% (w/v) in culture broth in which crude oil was used as carbon and energy sources appeared to be an optimum. Optimal culture conditions of strain OM1 were different from those of the soil microorganisms except for temperature. The growth of strain OM1 was optimized at pH 7 and crude oil of 3.0% (w/v). The degradability to crude oil by strain A132 showed maximum $5.49g/\;l\;{\cdot}\;day$ under the conditions of $25^{\circ}C$, NaCl of 1.0% (w/v), and crude oil of 2.0% (w/v). The highest degradability of strain F722 to crude oil was $1.19g/\;l\;{\cdot}\;day$ under the culture conditions at $35^{\circ}C$, NaCl 1.0% (w/v), and crude oil of 2.0% (w/v). The degradation characteristics of kerosene $(nC_9-nC_{20})$ and diesel $(nC_9-nC_{28})$ by strain OM1, and F722 were analyzed by gas chromatography. Strain OM1 degraded more than 95% of kerosene and 75% of diesel for 7 days cultivation. Strain F722 showed degradation of more than 80% to kerosene in 10 days.

• Korean Journal of Food Science and Technology
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• v.40 no.6
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• pp.611-620
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• 2008

The principal objective of this study was to assess the effects of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) extracted from egg yolk on the oxidation of tocopherol-stripped canola oil and its browning, as well as their content changes during 12 hr of heating at $180^{\circ}C$. PC and/ or PE contents in the oil were measured at 200, 500, 1,000, or 2,000 ppm. PL contents in the oil and oil browning were determined by high performance liquid chromatography (HPLC) and spectrophotometry, respectively. The oil oxidation was evaluated by the combination of fatty acid composition, conjugated dienoic acid content, and p-anisidine value. PC was degraded at a slower rate than PE during heating and the co-presence of PE reduced its rate of degradation. PE increased oil browning more profoundly than PC did. PC significantly reduced oil oxidation during heating; however, we noted a possible antagonism between PE and PC in reducing the oil oxidation. Egg yolk PC was a better antioxidant in oil oxidation during heating.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.902-910
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• 2018

In recent times, development of nanofluid insulation for power transformers is a hot research topic. Many researchers reported the enhancement in dielectric characteristics of nano modified mineral oils. Considering the drawbacks of petroleum based mineral oil, it is necessary to understand the dielectric characteristics of nanofluids developed with natural ester based oils. Palm oil has better insulation characteristics comparable to mineral oil. However very few research reports is available in the area of nanofluids based on palm oil. Partial discharge (PD) is one of the major sources of insulation performance degradation of transformer oil. It is essential to understand the partial discharge(PD) characteristics by collecting huge data base of PD performance of nano modified palm oil which will increase its confidence level for power transformer application. Knowing these facts, in the present work, certain laboratory experiments have been performed on PD characteristics of nano $SiO_2$ modified palm oil at different electrode configurations. Influence of concentration of nano filler material on the PD characteristics is also studied. Partial discharge inception voltage, Phase resolved partial discharge (PRPD) pattern, PD signal time-frequency domain characteristics, PD signal equivalent timelength-bandwidth mapping, Weibull distribution statistical parameters of PRPD pattern, skewness, repetition rate and phase angle variations are evaluated at different test conditions. From the results of the experiments conducted, we came to understand that PD performance of palm oil is considerably enhanced with the addition of $nano-SiO_2$ filler at 0.01%wt and 0.05%wt concentration. Significant reduction in PD inception voltage, repetition rate, Weibull shape parameter and PD magnitude are noticed with addition of $SiO_2$ nanofillers in palm oil. These results will be useful for recommending nano modified palm oil for power transformer applications.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.339-347
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• 2014

This study investigated the classification of olive oils that are mainly distributed in Korea via imports. The fatty acid contents, degree of color, pigments, anti-oxidants, and sterol contents are analyzed on the different types of olive oil as follows: 10 kinds of extra virgin olive oil, 5 kinds of pure olive oil, and 5 kinds of refined olive-pomace oil. As a result of fatty acid analysis, the majority of oleic acid ($C_{18:1}$) and palmitic acid ($C_{16:0}$), and minority of linoleic acid ($C_{18:2}$) and stearic acid ($C_{18:0}$) were detected without any significant differences between the grades of olive oils. The UV spectrum is related to the ${\Delta}K$, and it is a part of the analysis factor for the purity and degree of degradation of the oil. Extra virgin olive oil had ${\Delta}K$ of almost 0, pure olive oil had 0.07~0.12, and refined olive-pomace oil had 0.1~0.13. These differed from extra virgin oil, and the pure or pomace oil ${\Delta}K$ had a confirmed distinct difference. The color degrees of chlorophyll with a low $L^*$ value and $(-)a^*$ (green) and carotenoid with $(+)b^*$ (yellow) were confirmed to have correlation between extra virgin and other olive oils. To compare chlorophyll and carotenoid as natural pigment in olive oils, 417 nm and the ratio of the absorbance at 480 nm (417/480) was calculated at 1.62 of extra virgin, 1.85 of pure olive oil, and 3.32 of refined olive-pomace oil. Therefore, it will be possible to distinguish when the extra virgin or pure olive oil are mixed with olive-pomace oil. The total amount of tocopherol, an anti-oxidant, were 19.06 in extra virgin, 10.91 in pure olive oil, and 27.88 in refined olive-pomace oil. The high content of tocopherol in pomace oil caused recovery of solvent extraction from olive pulp. Thus, extra virgin oil and pure olive oil were distinguished by olive-pomace oil. Polyphenol compounds in extra virgin olive oil measured high only in ferulic acid with 0.543 mg/kg, caffeic acid with 0.393 mg/kg, and other vanillic acid, vanillin, and p-coumaric acid had similar amount of 0.3 mg/kg. All grade of olive oils had the highest ${\beta}$-sitosterol content. Af (Authenticity factor) value were estimated with campesterol and stigmasterol content ratio (%). Af value was 19.2 in extra virgin olive oil, 17.1 in pure olive oil, 16.9 in refined olive-pomace oil, which were distinctive from sunflower oil with 3.7, corn oil with 2.4, and soybean oil with 2.0. It can provide important indicator of olive oil adulteration with other cheap vegetable oils. The results of this study can be used as a database for the classification of olive oil grade and distinguishing between the different types of oils.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.74-81
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• 1993

To investigate the oil degrading properties of psychrotrophic bacterium Acinetobacter calcoaceticus Al-l the effects of environmental factors on this bacterium were studied. The optimal environmental conditions for cell growth rate and oil-emulsifying activity were as follows; temperature $15^{\circ}C$, pH 7.5, salt concentration 0- 3% and crude oil concentration 0.1%. Additionally the optimal concentration of Nand P source for cell growth rate and oil-emulsifying activity were 0.76 mM and 0.057 mM as $(NH_4)HS0_4$ and $K_2HP0_4$, respectively. Analysis of remnant oil by gas chromatography showed time dependent oil degradation pattern by A. calcoaceticus during cultivation; At lOoe and $15^{circ}$e, most alkane peaks were disappeared and it showed large quantities of crude oil were degraded. But at $25^{circ}$e alkane compounds in the crude oil were partially degraded even after 120 hours incubation.

• Journal of Environmental Science International
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• v.17 no.7
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• pp.795-799
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• 2008

We have studied bioremediation of effective microorganisms on crude oil spill in Taean, west-coast of Korea. Oil contaminated soil samples were collected on December 14, 2007, seven days after the Hebei Spirit oil-spilled accident. Total petroleum hydrocarbon (TPH) was measured to evaluate the effectiveness of effective microorganisms (EM) which were composed with yeast, photosynthetic bacteria and lactic acid bacteria on oil degradation. TPH concentration before EM treatment was 323.8 mg/kg, whereas TPH concentrations on 2 days after EM treatment and that of control (without EM) was 102.1 mg/kg and 170.6 mg/kg, respectively. On six days after EM treatment TPH was 91.3 mg/kg and that of control was 127.7 mg/kg. Percentages of degraded crude oil were 47.3% without EM and 68.5% with EM, 60.6% without EM and 71.8% with EM on 2 and 6 days after EM treatment, respectively. These results clearly showed that the application of effective microorganisms toward oil-contaminated soil was quite useful to degrade crude oil spill. These results were derived from the effects of biostimulation of microbial media nutrients and bioaugmentation of effective microorganisms. If we carefully apply these effective microorganisms, it can be a useful bioremediation method to recover oil-contaminated marine ecosystems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.457-464
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• 2010

Representative methods for removing spilled oil include mechanical skimming, chemical treatment, burning at the surface of the spilled oil, and microbiological degradation. Among these methods, mechanical skimmer is the most efficient. Mechanical skimming can be classified into the following categories: belt-type, disk-type, weir-type, drum-type. We designed models with a submerged orifice for use in our experiments, for an objective and systematic evaluation of the recovery efficiency of mechanical skimming. Basically, oil is lighter than seawater and hence tends to float on the surface of the latter if there is sufficient time for floating. The present skimmer is kind of wear-type with the submerged orifice for seawater to be squeezed through, minimizing water content in the tank. From the experimental results, we identify the parameters that influence the oil recovery rate and recovery efficiency. The recovery efficiency can be enhanced by increasing the thickness of the oil layer in the first oil accumulative tank.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.309-323
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• 2019

Fish oil consists of omega-3 fatty acids which play an important role in human health. Its susceptibility to oxidation causes considerable degradation during the processing and storage of food products. Accordingly, encapsulation of this ingredient through freeze drying was studied with the aim of protecting it against environmental conditions. Gum arabic (GA) was used as the wall material for fish oil nanoencapsulation where tween 80 was applied as the emulsifier. A water-in-oil (W/O) emulsion was prepared by sonication, containing 6% fish oil dispersed in aqueous solutions including 20% and 25% total wall material. The emulsion was sonicated at 24 kHz for 120 s. The emulsion was then freeze-dried and the nanocapsules were incorporated into probiotic fermented milk, with the effects of nanocapsules examined on the milk. The results showed that the nanoparticles encapsulated with 25% gum arabic and 4% emulsifier had the highest encapsulation efficiency (EE) (87.17%) and the lowest surface oil (31.66 mg/100 kg). Using nanoencapsulated fish oil in fermented milk significantly (p<0.05) increased the viability of Lactobacillus plantarum as well as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents. The fermented milk sample containing fish oil nanoencapsulated with 25% wall material and 4% emulsifier yielded the greatest probiotic bacterial count (8.41 Log CFU/mL) and the lowest peroxide value (0.57 mEq/kg). Moreover, this sample had the highest EPA and DHA contents. Utilizing this nanoencapsulated fish oil did not adversely affect fermented milk overall acceptance. Therefore, it can be used for fortification of low fat probiotic fermented milk.