Enzymatic Synthesis of Butyl Laurate by Immobilized Rhizopus Oryzae Lipase onto Silica Aerogel: Optimization by Response Surface Methodology
Nadia Kharrat, Imen Aissa, Amel Kamoun, Yassine Ben Ali, Maha Chaâbouni-Karra and Youssef Gargouri
Affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS route de Soukra, BP1173, University of Sfax, 3038 Sfax, Tunisia.
Keywords: Esterification of butyl laurate, Immobilized Rhizopus oryzae lipase, silica aerogel, Response surface methodology
(RSM), Box-Behnken Design, Cosmetic and oleochemistry fields.
Given the importance of butyl laurate in various industrial fields, its production by enzymatic catalysis has received
greater interest. Butyl laurate was successfully synthesised by the esterification of lauric acid with butanol. This reaction
was catalyzed by Rhizopus oryzae lipase immobilized onto silica aerogel in organic media. Response surface methodology
was applied in order to approximate the effect of the butanol/ lauric acid molar ratio (1.2-5 mol/mol), the amount
of lipase (100-700 IU) and the volume of hexane (3-9 mL) on the butyl laurate lipase-catalyzed esterification yield
through an empirical model. Results clearly indicated that the lipase amount was the main factor influencing the synthesis
yield. This yield increased with the lipase amount and decreased with the molar ratio of butanol/ lauric acid and the volume
of hexane. The selected optimal conditions for synthesis were: a butanol/ lauric acid molar ratio of 1.2, a lipase
amount of 550 IU and an hexane volume of 3 mL. The application of these optimized conditions led to a butyl laurate
yield of 90.5%. The immobilized lipase was successfully reused for 26 cycles without a significant decrease of the conversion
yield on butyl laurate. These results confirm the idea that employing Rhizopus oryzae lipase immobilized onto silica
aerogel for a wide range of esterification reactions is feasible.
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