Aspergillus oryzae Lipase-Catalyzed Synthesis of Dioleoyl; Palmitoyl-Rich Triacylglycerols in Two Reactors
Dioleoyl; palmitoyl-rich triacylglycerols (OPO-rich TAG) were synthesized through Aspergillus oryzae lipase (AOL)-catalyzed acidolysis of palm stearin with commercial oleic acid by a one-step process in a stirred tank reactor and continuous packed bed reactor to evaluate the feasibility of using immobilized AOL. AOL was found to be valuable for the synthesis of OPO-rich TAG when compared with commercial lipase from Thermomyces lanuginose (Lipozyme ® TL IM; Novozymes A/S, Bagsvaerd, Denmark). The C52 (triglycerides with a carbon number of 52, stands for OPO, OPL, LPL and their isomers) content of AOL was higher (45.65 %), and the intensity of treatment (IOT: lipase amount × reaction time/TAG amount) of AOL was just 6.25 % of that of Lipozyme ® TL IM under similar reaction conditions in the stirred tank reactor. Response surface methodology were used to optimize the reaction conditions of the AOL-catalyzed acidolysis is reaction in the packed bed reactor. The optimal point for the set of experimental conditions generated were as follows: residence time 3.0 h; temperature 62.09 °C; substrate molar ratio 7.13 mol/mol. The highest C52 content obtained was 48.60 ± 2.36 %, with 57.46 ± 1.72 % total palmitic acid at the sn -2 position and 74.21 ± 2.45 % oleic acid at the sn -1,3 positions. The half-life of AOL was 24 h in the stirred tank reactor and 140 h in the packed bed reactor. The immobilized AOL achieved similar conversion and selectivity to commercial lipases for the catalyzed synthesis of OPO-rich TAG and may offer a cheaper alternative.
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