M. A. Alim
Department of Food Technology and Rural Industries, Bangladesh Agricultural
University, Mymensingh-2202, Bangladesh
J. H. Lee
Department of Food Science and Technology, Chungnam National University, Taejeon 305-764, South Korea
C. R. Lee
Department of Food Science and Technology, Chungnam National University, Taejeon 305-764, South Korea
C. C. Akoh
Department of Food Science and Technology, The University of Georgia, Athens, GA 30605, USA
K. T. Lee
Department of Food Science and Technology, Chungnam National University, Taejeon 305-764, South Korea
Mustard oil, Erucic acid, Crystallization, Triacylglycerol
Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh
Knowledge Management
Mustard oil (MO) was supplied from Agricultural Marketing Co. Ltd. (Dhaka, Bangladesh). The lipase (Lipozyme TL IM) used was the immobilized preparation of a 1,3-specific produced from Thermomyces lanuginosus, obtained from Novozymes A/S (Bagsvaerd, Denmark). Having specific activity is 175 IUN/g density, 0.54 g/ml width, 0.3-1.0 mm particle diameter and 5 w/w % of water content. Acetone, n-hexane, 2- propanol, heptadecanoic acid, capric acid and acetic acid were obtained from Sigma- Aldrich Chemical Co. (St. Louis, MO, USA). The pancreatic lipase was purchased from Sigma Chemical Co. (St. Louis, MO, USA). MO (300 ml) and acetone (1500 ml) were mixed (ratio = 1: 5, v/v) together in a 3-L conical flask. The conical flask was placed in a deep freezer at different temperatures (-10, –16 and -24oC) for fractionation. After 24 h, the liquid phase was separated from the solid phase by decanting, and acetone was completely evaporated from liquid or solid phase of MO using a rotary vacuum evaporator and dried with nitrogen. Liquid and solid phases were used for further study. TAG from MO, liquid and solid phase of fractionated MO were separated on a silica gel 60 F254 plate developed with hexane/diethyl ether/acetic acid (50/50/1, v/v/v) and detected under short (254 nm) wavelengths. TAG band was scraped off into a screwcapped tube and methylated by 6% H2SO4 in methanol for 1 h at 70oC. Fifty μl heptadecanoic acid (C17:0, 1 mg/ml in hexane) as an internal standard was also added in the tube. After putting on ice immediately, 2 ml hexane was added and vortexed for 30 sec. The upper layer was passed through an anhydrous sodium sulfate column, and dried with nitrogen. Fatty acids were analyzed by gas chromatography (GC, Agilent, HP 6890 Series, Avondale, PA), accompanied with auto-injection and flame-ionization detection and a fused-silica capillary column (SP-WAX, 60 m x 0.25 mm id, Supelco, Bellefonte, PA). Temperature gradient was 100°C to 220°C with an increasing rate 4°C/min. Nitrogen was used as a carrier gas with flow rate 52 ml/min with split mode (50:1). The temperature of injector and detector were 250 and 260°C, respectively. All analysis and quantification were conducted in duplicate. The MO, liquid and solid phase of fractionated MOs (7 mg) were taken in a test tube. Seven ml of Tris-HCl buffer (pH 7.6), 1.75 ml of 0.05% bile salt, 0.7 ml of 2.2% CaCl2 and 7 mg of pancreatic lipase were mixed and vortexed for 30 sec. Other steps were followed as described. The hydrolytic products were separated on silica gel 60 F254 plate with a solvent system of hexane: diethyl ether: acetic acid (50:50:1, v/v/v). The band of monoacylglycerol was scrapped off for methylation and analyzed by GC. Percentage of fatty acid at sn-1,3 position was calculated by the formula : sn-1,3 (%) = (3 T –sn-2)/2 where T is the total fatty acid contents of MO, liquid and solid phase of MO, respectively.The statistical analysis system (SAS, 2002) was used to perform statistical analysis. Duncan’s multiple range tests was performed on the means of values. The tested significance was considered at 5% level.
Progress. Agric. 19(1) : 135-141, 2008 ISSN 1017-8139
Journal