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Abdelkader Ali-Nehari,김선봉,Yang-Bong Lee,전병수 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
In this study, Enzyme activities of krill were characterized before and after lipid extraction by supercritical carbon dioxide (SC-CO2) and organic solvent, n-hexane and acetone. Krill SC-CO2 extraction was performed under the conditions of temperature range from 35 to 45 8C and pressure, 150–250 bar for 2.5 h with a constant flow rate of 22 g/min. Extraction yields of lipids increased with pressure and temperature. The digestive enzyme activities of protease, lipase and amylase of SC-CO2 treated krill residues were slightly decreased comparing to organic solvent, n-hexane and acetone treated residues. In SC-CO2 treated samples, all of the digestive enzymes showed slightly higher temperature stability. In the other hand the crude extracts of SC-CO2 and n-hexane treated krill samples showed almost same optimum pH and pH stability for each of the digestive enzymes. It was also found in SDS-PAGE that there are no significant differences in protein patterns of the crude extracts of untreated, SC-CO2, n-hexane and acetone treated krill indicating no denaturation of proteins.
Abdelkader Ali-Nehari,전병수,김선봉,Yang-Bong Lee,Hye-youn Lee 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
Krill oil including astaxanthin was extracted using supercritical CO2 and hexane. The effects of different parameters such as pressure (15 to 25MPa), temperature (35 to 45℃), and extraction time, were investigated. The flow rate of CO2 (22 gmin−1) was constant for the entire extraction period of 2.5 h. The maximum oil yield was found at higher extraction temperature and pressure. The oil obtained by SC-CO2 extraction contained a high percentage of polyunsaturated fatty acids, especially EPA and DHA. The acidity and peroxide value of krill oil obtained by SC-CO2extraction were lower than that of the oil obtained by hexane. The SC-CO2 extracted oil showed more stability than the oil obtained by hexane extraction. The amount of astaxanthin in krill oil was determined by HPLC and compared at different extraction conditions. The maximum yield of astaxanthin was found in krill oil extracted at 25 MPa and 45℃.
Abdelkader Ali-Nehari,전병수 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.7
Purification of phospholipids (PL) from the Antarctic krill (Euphausia superba) using a two-step extraction process has been investigated. Using supercritical carbon dioxide (SC-CO2) extraction with optimal extractions conditions of 45 oC, 25MPa, and CO2 flow rate of 22 g/min, most of the neutral lipids were extracted. PC, PE and PI were then extracted in a second step conducted with modified existing method using ethanol, hexane and acetone as solvents. The major PL of krill residues was quantified by high performance liquid chromatography (HPLC-ELSD). The fatty acid compositions of total PL, PC, PE and PI were analyzed by gas chromatography (GC). A significant amount of polyunsaturated fatty acids (PUFA) was present in both total and PLs fractions. The purified PLs were characterized by their acid value, peroxide value, and the oxidative stability. The purity of PL ranged between 93 and 97% and was evaluated by spectrophotometry.
Jung-Nam Park,전병수,Abdelkader Ali-Nehari,우희철 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.11
We investigated the thermal stability of polyphenols and fatty acids from Laminaria japonica powder by subcritical water hydrolysis among the range of the experimental conditions. The experiment was carried out at temperatures and pressures ranging from 200 to 280 oC and 13 to 60 bar, respectively for 28 to 42 min. Polyphenol and fatty acids in hydrolysates obtained from different conditions were analyzed by GC and UV-spectrophotometer. The results were compared with those obtained from Laminaria japonica oils extracted by supercritical CO2. Polyphenol and several fatty acids in hydrolysates produced by subcritical water showed high thermal stability.