Enzymatic Synthesis of Ascorbyl Palmitate in Organic Solvents: Process Optimization and Kinetic Evaluation

Food and Bioprocess Technology (Impact Factor: 3.13). 01/2012; 5(3):1068-1076. DOI: 10.1007/s11947-010-0398-1

ABSTRACT This work is focused on the optimization of reaction parameters for the synthesis of ascorbyl palmitate catalyzed by Candida antarctica lipase in different organic solvents. The sequential strategy of experimental designs proved to be useful in maximizing the
conditions for product conversion in tert-butanol system using Novozym 435 as catalyst. The optimum production were achieved
at ascorbic acid to palmitic acid mole ratio of 1:9, stirring rate of 150rpm, 70°C, enzyme concentration of 5wt.% at 17h
of reaction, resulting in an ascorbyl palmitate conversion of about 67%. Reaction kinetics for ascorbyl palmitate production
showed that very satisfactory reaction conversions (∼56%) could be achieved in short reaction times (6h). The kinetic empirical
model proposed showed ability to satisfactory represents and predict the experimental data.

KeywordsBiocatalysis–Neural network–Kinetics–Lipase–Ascorbyl palmitate–Experimental design

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The main focus of this work was to investigate the residual esterification activity and the product conversion after 10 successive cycles of utilization of a commercial lipase in three systems: esterification of 2-ethyl hexanol and palmitic acid in a solvent-free system; esterification of ascorbic acid and palmitic acid in tert-butanol; and transesterification of glycerol and methyl benzoate in 2-propanol. These systems were chosen based on previous results by our research group in terms of product conversion. Before scale-up, there is a need for evaluating several cycles of utilization of the biocatalyst. The esterification of 2-ethyl hexanol showed that after 10 cycles the enzyme retained 90% of its activity. The system consisting of ascorbic acid, palmitic acid, Novozym 435 and tert-butanol showed that a reduction in enzyme activity was accompanied by a reduction in reaction conversion; the same behavior was not observed for the third system.
    Brazilian Journal of Chemical Engineering 06/2011; 28(2):181-188. · 0.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present study, a dimethyl sulfoxide (DMSO)–acetone mixed solvent was used as a reaction medium to study lipase-catalyzed esterification of l-ascorbic acid with lauric acid as the acyl donor. Compared with the solvent of acetone, the mixed solvent not only could greatly improve the solubility of l-ascorbic acid but also could observably increase the enzymatic rate. Within the investigated range of substrate concentrations, a lauric acid/ascorbic acid mole ratio of 3:1 was found to be optimum. Moreover, the optimum production was achieved in the reaction medium dewatered by molecular sieves and at a lipase loading of 40 mg/mL. As a result, enzymatic synthesis of ascorbyl laurate gave a maximum conversion of 94% in the DMSO–acetone mixed solvent using lauric acid as the acyl donor.
    Industrial & Engineering Chemistry Research. 08/2013; 52(34):11875–11879.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Kinetics and thermodynamics of lipase-catalyzed esterification of L-ascorbic acid in acetone was investigated by using vinyl acetate as acyl donor. The results showed that L-ascorbic acid could generate inhibition effect on lipase activity. A suitable model, Ping-Pong Bi-Bi mechanism having substrate inhibition, was thus introduced to describe the enzymatic kinetics. Furthermore, the kinetic and thermodynamic parameters were calculated from a series of experimental data according to the kinetic model. The inhibition constant of L-ascorbic acid was also obtained, which seemed to imply that enhancing reaction temperature could depress the substrate inhibition. Besides, the activation energy of the first-step and the second-step reaction were estimated to be 37.31 and 4.94kJ/mol, respectively, demonstrating that the first-step reaction was the rate-limiting reaction and could be easily improved by enhancing temperature.
    Journal of Biotechnology 11/2013; · 3.18 Impact Factor


Available from
Oct 30, 2014