67C-13 |
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K.-T. Lee1, E. CHO1, and J.-H. Lee2. (1) Department of Food Science and Technology, Chungnam National University, 220 Gung-Dong, Yusung-Ku, Taejon 305-764, South Korea, (2) Department of Food and Nutrition, Chungnam National University, 220 Gung-Dong, Yusung-Gu, Taejon 305-764, South Korea In reaction media of low water activity, lipases preferentially catalyze the esterification rather than the hydrolysis of triacyglycerols. Through lipase-catalyzed esterification, natural fats and oils can be intentionally modified to have a predetermined composition and distribution of fatty acyl groups on the glycerol backbone when using a regiospecific lipase. Such modified lipids are commonly referred to as structured lipids (SL). Short and medium chain triacylglycerols, namely tributyrin (1,2,3-tributyrylglycerol) and tricaprylin (1,2,3-trioctanoylglycerol), were interesterified with macadamia oil using an immobilized lipase as biocatalyst as SL. Normal phase (silica column) and reverse phase (ODS column) HPLC using light-scattering detection was used to separate the isomeric SL components, and HPLC with mass detection was used to identify each SL-TAG molecule species in the reaction mixtures Both normal phase (silica column; NPSIL) and reverse phase (ODS column) high performance liquid chromatography accompanied with evaporative light scattering or mass spectrometric detection were used to separate and/or identify the newly synthesized structured lipid products. The NPSIL method successfully separated the regioisomers of the structured triacylglycerols composed of mixed short/medium (butyric or caprylic moiety) and long chain fatty acids. From these results, 77.6 and 94.1% of the triacylglycerol species were structured lipid molecules produced from tributyrin and tricaprylin, respectively. Analysis of the structured triacylglycerols by non-aqueous reverse phase high performance liquid chromatography separated the regioisomeric triacylglycerols based on their total carbon number. SL-TAG containing medium chain fatty acid (i.e. caprylic acid) did not resolve fully the positional isomers and SL-TAG with medium and long chain fatty acids would be better separated by reverse-phase HPLC than normal phase HPLC. When neublizer gas flow and tube temperature were optimized, ELSD can fully detect SL-TAG molecules. This study enabled the separation of SL-TAG isomers of short, medium, and long chain fatty acids effectively so that lipase-catalyzed reactions for the synthesis of SL-TAG were monitored to produce a high content of desirable SL-TAG stereoisomers.
Session 67C, Food Chemistry: Food analysis, irradiation and toxicology
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