• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.504-514
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• 2017

This study was carried out to investigate the emulsifying properties of concentrated red ginseng extract (CRGE). First, we determined the interfacial tension of CRGE at the oil-water interface. Second, oil-in-water emulsions were prepared with CRGE and then their physicochemical properties such as fat globule size, zeta-potential, dispersion stability, and microscopic characteristics were determined. It was found that interfacial tension gradually decreased with increasing CRGE concentration, indicative of some surface activity. In emulsions, fat globule size was decreased as CRGE concentration increased, showing a critical value ($d_{43}$ ≒ $0.39{\mu}m$) at ${\geq}3.5wt%$ of CRGE. In addition, pH and NaCl also influenced on fat globule sizes; they were increased in acidic conditions ($pH{\leq}3$) or in higher NaCl concentration (${\geq}0.4M$) and these results were interpreted in view of the change in zeta potentials. The dispersion stability by separation analyzer ($LUMiFuge^{(R)}$) showed that it was more stable in emulsions with higher CRGE concentration (i.e., ${\geq}3.5wt%$). In conclusion, CRGE was surface-active and it could be used as an emulsifier in preparation of food emulsions.

• Polymer(Korea)
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• v.28 no.2
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• pp.103-110
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• 2004

The biodegradable poly($\varepsilon$-caprolactone) (PCL) microcapsules containing tocopherol were prepared by oil-in-water emulsion solvent evaporation method. The features of the microcapsules were investigated in the manufacturing conditions and degradation behaviors. The form and structural feature of the microcapsules were measured by scanning electron microscope and X-ray diffraction, respectively. The surface free energy of the microcapsules was executed using contact angle measurement. As a result, the microcapsules were more stable and spherical with poly(vinyl alcohol) given in a surfactant. The surface free energy and crystallinity of microcapsules were decreased with increasing the core concentration, and degradation of PCL was occurred after 21 days. The release behaviors were examined by Uv/vis. spectrophotometer. It was found that the release rate of the microcapsules was increased with increasing the stirring rate, due to the increased interface between microcapsules and release media.

• Microbiology and Biotechnology Letters
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• v.31 no.4
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• pp.311-321
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• 2003

Bacteria produce lipases, which can catalyze both the hydrolysis and the synthesis of long chain triglycerides. These reactions usually proceed with high regioselectivity and enantioselectivity, and, therefore, lipases have become very important biocatalysts used in organic chemistry. 3D lipase structures were solved from several bacterial lipases. They have an $\alpha/\beta$ hydrolase fold and a catalytic triad consisting of a nucleophilic serine, and an aspartate or glutamate residue that is hydrogen bonded to a histindine. Active sites are covered with $\alpha$-helical lid structure, of which movement is involved in the enzyme's activation at oil/water interface. Four substrate binding pockets were identified for triglycerides: an oxyanion hole and three pockets accommodating the fatty acids bound at positions sn-1, sn-2, and sn-3. These pockets determine the enantiopreference of a lipase. The understanding of structure-function relationships as well as the development of molecular evolution techniques will enable researchers to tailor new lipases for biotechnological applications.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.24-30
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• 2010

This study utilises repeated numerical tests to understand the effects of variable near-surface conditions on time-lapse seismic surveys. The numerical tests were aimed at reproducing the significant scattering observed in field experiments conducted at the Naylor site in the Otway Basin for the purpose of $CO_2$ sequestration. In particular, the variation of elastic properties of both the top soil and the deeper rugose clay/limestone interface as a function of varying water saturation were investigated. Such tests simulate the measurements conducted in dry and wet seasons and to evaluate the contribution of these seasonal variations to seismic measurements in terms of non-repeatability. Full elastic pre-stack modelling experiments were carried out to quantify these effects and evaluate their individual contributions. The results show that the relatively simple scattering effects of the corrugated near-surface clay/limestone interface can have a profound effect on time-lapse surveys. The experiments also show that the changes in top soil saturation could potentially affect seismic signature even more than the corrugated deeper surface. Overall agreement between numerically predicted and in situ measured normalised root-mean-square (NRMS) differences between repeated (time-lapse) 2D seismic surveys warrant further investigation. Future field studies will include in situ measurements of the elastic properties of the weathered zone through the use of 'micro Vertical Seismic Profiling (VSP)' arrays and very dense refraction surveys. The results of this work may impact on other areas not associated with $CO_2$ sequestration, such as imaging oil production over areas where producing fields suffer from a karstic topography, such as in the Middle East and Australia.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.642-652
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• 2014

The synthesis of octenyl succinyl ${\beta}$-gucan (OSA-${\beta}$-glucan) was carried out and its interfacial properties at the oil-water interface and in emulsion systems were investigated. An aqueous ethanol system as a reaction media was used to facilitate the synthesis process; 10% (w/w) ethanol found to be the best as it showed a maximum degree of substitution (DS: 0.0132). FT-IR showed a characteristic absorption spectrum at $1736cm^{-1}$, indicating the esterification of octenyl succinyl groups to ${\beta}$-glucan backbone. As for interfacial tension measurements, it was decreased with increasing concentration of OSA-${\beta}$-glucan in the aqueous phase and when NaCl was added to aqueous OSA-${\beta}$-glucan solution in the range of 0.01 M to 0.1 M and also when pH was raised (pH 3 ~ pH 9). In systems of emulsion stabilized with OSA-${\beta}$-glucan, fat globule size found to decrease with increasing concentration of OSA-${\beta}$-glucan, showing a critical value of about $0.32{\mu}m$ at 0.5 wt%. When the OSA-${\beta}$-glucan emulsions were stored, it was found that fat globule size was increased with storage time and particularly pronounced increase was observed in emulsion with 1% OSA-${\beta}$-glucan, possibly due to depletion flocculation. Results of creaming stability evaluated by light scattering technique showed that it was more stable in emulsions containing smaller fat globule size. Surface load of OSA-${\beta}$-glucan in emulsions increased with increasing concentration of OSA-${\beta}$-glucan, suggesting a multilayer adsorption.

• Food Engineering Progress
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• v.15 no.2
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• pp.175-181
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• 2011

By using supercritical carbon dioxide fluid, an attempt was made to extract surface-active substances from defatted rice bran. Extraction was carried out according to D-optimal design and results were analyzed by response surface methodology to establish optimum condition. It was found that pressure, temperature and co-solvent (ethanol) influenced in a different extent on the extraction efficiency (i.e., yield and interfacial tension) of surface-active substances. Among them, co-solvent was found to be a major influencing factor, where maximum yield (2.62%) was observed at the highest content (250 g). In addition, it also affected most on the interfacial tension at the oil-water interface but in this case the lowest interfacial tension value (9.51 mN/m) was found when added lowest (50 g). In conclusion, it was estimated that the optimum extraction condition was to be pressure 350bar, temperature $62^{\circ}C$ and co-solvent content 50 g in this study, where extraction yield was 0.69% and interfacial tension to be 10.1 mN/m.