Using tricaprylin (TC) and trilinolenin (TLN) as substrates, biosynthesis of medium-long-medium (MLM) type structured lipids (SLs), by Lipozyme IM from Rhizomucor meihei and Novozym 435 from Candida antarctica , was investigated to determine their capacity as biocatalysts for the biosynthesis of SLs. At 30°C, Lipozyme IM showed higher bioconversion yield (24.7%) and initial enzyme activity (6.3 mumol CLnC/g enzyme/min) as compared to that of 24.0% and 1.6 mumol CLnC/g enzyme/min, respectively, for the Novozym 435 at 50°C. As a result, Lipozyme IM was subsequently used for further investigations. The SLs were recovered and characterized by silver-ion exchange high-performance liquid chromatography and gas-liquid chromatography. The structural analyses indicated that the major products of the enzymatic reaction were 1,3-dicapryl-2-linolenyl glycerol (CLnC) and 1(3)-capryl-2,3(1)-dilinolenyl glycerol (CLnLn). In order to optimize the bioconversion yield of CLnC, selected parameters, including initial water activity and solvent type, lipase concentration (5 to 20 mg solid enzyme), substrate molar ratios (TC:TLN of 1:4 to 8:1) and molecular sieve (5 to 20 mg/mL, Type 3A), were investigated. The experimental results showed that using hexane at initial aw 0.06, 10 mg solid enzyme/mL and substrate molar ratio of TC to TLN of 6:1 resulted in the highest bioconversion yield of 73.2% of CLnC. However, the addition of molecular sieve to the reaction medium resulted in a 14.0% decrease in the bioconversion yield of CLnC. Using the optimized conditions, the effects of TLN concentration and other selective limiting parameters, including the denaturation of enzyme, aw and the formation of glycerol layer, on the mass productivity (PM), enzymatic productivity (PE) and volumetric productivity (PV) of the interesterification reaction were investigated. Using 80 mM TLN, the maximum PM of 15.5 mg CLnC/g substrates/h was obtained; however, using 200 mM TLN, the maximum PE and PV were 0.07 mg/enzyme unit/h and 6.1 g CLnC/L/h, respectively. The addition of 3 mg Silica gel to the reaction medium resulted in 52.0, 37.3 and 37.3% increase in PM, PE and PV, respectively.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.111598 |
| Date | January 2009 |
| Creators | Bai, Shan, 1976- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 003135275, proquestno: AAIMR66901, Theses scanned by UMI/ProQuest. |
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