• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.404-410
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• 2017

An analytical method for determination of propylene glycol alginate (PGA) in food products was developed by HPLC-size-exclusion chromatography. The GF-7M HQ column and LT-ELSD detector were determined by considering the instrumental analysis conditions for PGA analysis. The pretreatment method for the analysis of PGA was suitable for 3 hr extraction at $20^{\circ}C$ and 150 rpm according to the extraction temperature. Linearity ($R^2$) for the analysis of PGA was 0.9873 at calibration curve range of 300, 500, 700, 1,000, and 1,500 mg/kg (5 points). The limit of detection and limit of quantification of PGA on HPLC system was 171.43 and 519.50 mg/kg, respectively. The accuracy and coefficient of variation obtained by size-exclusion chromatography were 86.1~110.4% and 4.1~13.5%, respectively. By applying the HPLC-size-exclusion chromatography system, it was possible to analyze the contents of PGA in 134 different types of food products.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.282-287
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• 2001

This study was carried out to investigate the difference of ginsenoside compositions in crude ginseng saponins prepared by five different methods including three new methods. Two known methods are hot methanol(MeOH) extraction/n-butanol(n-BuOH) fractionation and hot MeOH extraction/Diaion HP-20 adsorption/MeOH elution. Three new methods are hot MeOH extraction/cation AG 50W $absorption/H_2O$ elution/n-BuOH extraction, cool MeOH extraction/Diaion HP-20 adsorption/MeOH elution and direct extraction with ethyl acetate(EtOAc)/n-BuOH. Analysis of ginsenoside composition in the crude saponins by conventional HPLC/RI(Refractive Index) did not show great difference between methods except EtOAc/n-BuOH method. However, HPLC/ELSD (evaporative light scattering detector) employing gradient mobile phase afforded fine resolution of ginsenoside Rf, $Rg_1$ and $Rh_1$, and great difference of ginsenoside compositions between methods. LC/MS revealed that large amount of prosapogenins were produced during the pass through the cation exchange (AG 50W) column being strongly acidic. Six major ginsenosides such as $Rb_1,w;Rb_2,$ Rc, Rd, Re and $Rg_1$, 5 prosapogenins and one chikusetsusaponin were identified by LC/MS. A newly established HPLC method employing ODS column and gradient mobile phase of $KH_2PO_4/CH_3CN$ revealed that malonyl ginsenosides were detected only in the crude saponin obtained from cool MeOH extraction.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.308-313
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• 1999

Total polar lipid produced from the soybean oil and lard by heating with different surface area at $185^{\circ}C$ were measured by silica gel column chromatography. Further, the polar lipid was fractionated by high performance size exclusion chromatography-evaporative light scattering detector (HPSEC-ELSD). The HPSEC system was composed of two GPC columns $(100\;{\AA}\;and\;500\;{\AA})$ and a THF mobile phase. With this system it was possible to fractionate into the free fatty acid, diglyceride, triglyceride monomer, triglyceride dimer and triglyceride polymers. The triglyceride monomer, triglyceride dimer and triglyceride polymers significantly increased as the heating time and surface area increased. But diglyceride and free fatty acid did not increased as the heating time and surface area increased. Triglyceride polymer (r>0.93), triglyceride dimer (r>0.97), triglyceride monomer (r>0.95) showed a high correlation with polar lipid content. On the other hand, diglyceride (r<0.68) and free fatty acid (r<0.76) were not significantly correlated with the polar lipid content. These results indicated that a major oxidative components formed during thermal oxidation were triglyceride polymers and triglyceride dimer and triglyceride monomer.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.741-746
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• 2010

Phospholipids were recovered from squid viscera residues by ethanol extraction after supercritical carbon dioxide($SCO_2$) extraction and from squid viscera was not processed $SCO_2$ by various organic solvent extraction. $SCO_2$ extraction were performed at $45^{\circ}C$ and 20 MPa for removal of non polar lipid molecules from freeze dried squid viscera sample. Phospholipids were extracted from freeze dried squid viscera sample by chloroform, hexane, methanol, and ethanol and from $SCO_2$extracted squid viscera sample by ethanol. The pH was fixed at 5.7 for all phospholipids extraction conditions. Phospholipid classes were analyzed by HPLC equipped with evaporative light scattering detector (ELSD). Phosphatidyl choline(PC) extracted by ethanol from $SCO_2$ extracted residues was higher than that of extracted by ethanol from squid viscera. But phosphatidyl ethanolamine(PE) and phosphatidic acid(PA) were extracted higher percentage in raw squid viscera. The fatty acid compositions in phospholipids extract by ethanol extract from $SCO_2$ extracted residues were analyzed by gas chromatography(GC). Docosahexanoic acid(DHA) was found in highest percentage in phospholipid extract.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.593-598
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• 2009

In this study, the qualitative and quantitative analytical method for petroleum marker(Unimark 1494DB) in common diesel involved kerosene and byproduct fuel was developed using SPE pretreatment and high performance liquid chromatography. In SPE pretreatment process, the highest concentrated marker was obtained 15 minutes after addition of petroleum sample. The petroleum marker was detected with $1626.92mV{\cdot}sec$ intensity at 9.8 minutes retention time in 1 mg/L content in petrodiesel after pretreatment. Also petroleum marker was selectively identified in an acidic petroleum product which was previously difficult to be analyzed by UV-Vis Spectroscopy.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.72-76
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• 2007

In order to examine the biofunctions of glycosylceramide which is representative of sphingolipid, monoglycosylceramide (cerebroside) was isolated from rice bran extract. Crude glycosylceramides were isolated in large quantities and promptly by flash system column chromatography from rice bran extract, and purified by normal-phase HPLC using an evaporative light-scattering detector. One major cerebroside was obtained by HPLC used as an eluent consisting of chloroform, methanol and water (99:11:1, v/v/v), and the constituents were analyzed by MALDI/TOF-MS, FAB-MS, GC and 600 MHz $^1$H-NMR. The component sugar was estimated to be glucose. In the ceramide, the fatty acid component consist was 2-hydroxy arachidic acid. The long-chain base component was sphinga-4,8-dienine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.92-96
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• 2005

Among the failure modes which can be occurred in tube hydroforming such as wrinkling, bursting or buckling, the bursting by local instability under excessive tensile stresses is irrecoverable phenomenon. Thus, the accurate prediction of bursting condition plays an important role in producing the successfully hydroformed part without any defects. As the classical forming limit criteria, strain-based forming limit diagram has widely used to predict the failure in sheet metal forming. However, it is known that the FLD is extremely dependant on strain path throughout the forming process. Furthermore, the path-dependent limitation of FLD makes the application to hydroforming process, where strain path is no longer linear throughout forming process, more careful. In this work, stress-based forming limit diagram (FLSD), which is strain path-independent and more general, was applied to prediction of forming limit in tube hydroforming. Combined with the analytical FLSD determined from plastic instability theory, finite element analyses were carried out to find out Ihe state of stresses during hydroforming operation, and then FLSD is utilized as forming limit criterion. In addition, the approach is verified with a series of bulge tests in view of bursting pressure and shows a good agreement. Consequently, it is shown that the approach proposed in this paper will provide a feasible method to satisfy the increasing practical demands for judging the farming severity in hydroforming processes.

• Korean Journal of Pharmacognosy
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• v.38 no.2 s.149
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• pp.192-196
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• 2007

A rapid and practical HPLC assay was developed for quantitative analysis of saponins in Platycodi Radix. Seven saponin components in Platycodi Radix, i.e., deapioplatycoside E, platycoside E, deapioplatycodin D$_3$, platycodin D$_3$, polygalacin D$_2$, platycodin D$_2$ and platycodin D were successfully resolved on C18 column and detected by ELSD. Standard curves were linear over the concentration range 1 ${\sim}$2,000 ${\mu}$g/ml (r$^2$>0.992). Intra- and inter-day coefficients for variation of seven saponin components were < 10% and limit of quantification of them were around 0.7${\sim}$1.5 ${\mu}$g/ml, respectively. Using this method, contents of seven saponins in various plant materials under different cultivating conditions were estimated.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.356-362
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• 2010

Ceramide is important not only for the maintenance of the barrier function of the skin but also for the water-binding capacity of the stratum corneum. Although the exact role of ceramide in the human skin is not fully understood, ceramide has become a widely used ingredient in cosmetic and pharmaceutical industries. Compared with other microorganisms, yeast is more suitable for the production of ceramide because yeast grows fast and is non-toxic. However, production of ceramide from yeast has not been widely studied and most work in this area has been carried out using Saccharomyces cerevisiae. Regulating the genes that are involved in sphingolipid synthesis is necessary to increase ceramide production. In this study, we investigated the effect of the genes involved in the synthesis of ceramide, lcb1, lcb2, tsc10, lac1, lag1, and sur2, on ceramide production levels. The genes were cloned into pYES2 high copy number vectors. S. cerevisiae was cultivated on YPDG medium at $30^{\circ}C$. Ceramide was purified from the cell extracts by solvent extraction and the ceramide content was analyzed by HPLC using ELSD. The maximum production of ceramide (9.8 mg ceramide/g cell) was obtained when the tsc10 gene was amplified by the pYES2 vector. Real-time RT-PCR analysis showed that the increase in ceramide content was proportional to the increase in the tsc10 gene expression level, which was 4.56 times higher than that of the control strain.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.3
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• pp.365-370
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• 2012

Proximate composition, reducing sugar, and mineral content of several cultivars of Rehmannia glutinosa were analyzed. the moisture and soluble solid content of fresh Rehmannia glutinosa ('Korea', 'Kokang', 'Sewon 10', 'Sewon 11' and 'Jihwang 1') were 74.6~78.4% and $19.6{\sim}22.4^{\circ}Brix$, respectively. Proximate composition of dried Rehmannia glutinosa ranged from 82.91~86.94% carbohydrate, 3.38~5.70% crude protein, 2.5~3.0% crude ash and 3.47~3.80% fiber. Sugar composition by HPLC/ELSD showed that sucrose (4.49~7.75 g/100 g), raffinose (2.96~4.78 g/100 g) and stachyose (42.36~45.87 g/100 g) were present, whereas monosaccharides were not detected in 5 cultivars of dried Rehmannia glutinosa. Mineral compositions of dried Rehmannia glutinosa by ICP-AES were Ca (639.9~782.0 ppm), Fe (128.5~634.9 ppm), Na (119~150 ppm), K (6,639.1~10,448.0 ppm), Mg (372.2~981.8 ppm) and Zn (8.8~474.2 ppm). However, Co and Mo were not detected. Among 5 cultivars of Rehmannia glutinosa, 'Kokang' and 'Sewon 10' contain higher amounts of Fe, Ca, K, Mg, Cu and Zn than the other cultivars.