Lipase Mediated Isoamyl Acetate Synthesis in Solvent-Free System Using Vinyl Acetate as Acyl Donor

Annapurna Kumari¹, Paramita Mahapatra¹, Vijay Kumar Garlapati¹, Rintu Banerjee¹* and Swagata Dasgupta<sup>2

1</sup>Microbial Biotechnology and Downstream Processing Laboratory, Agricultural and Food Engineering
Department, Indian Institute of Technology, Kharagpur, IN-721302 West Bengal, India
²Department of Chemistry, Indian Institute of Technology, Kharagpur, IN-721302 West Bengal, India

Article history:
Received November 6, 2007
Accepted March 18, 2008

Key words:
isoamyl acetate, immobilized lipase, Rhizopus oryzae NRRL 3562, solvent-free system, transesterification, vinyl acetate

Summary:
Synthesis of isoamyl acetate, a flavour ester extensively used in food industry, has been carried out in a solvent-free system. In the present study, an attempt has been made to enhance the isoamyl acetate synthesis yield by transesterification of isoamyl alcohol with vinyl acetate using immobilized Rhizopus oryzae NRRL 3562 lipase. In the present synthesis, substrates had no inhibitory effect on immobilized lipase. The effects of various reaction parameters on isoamyl acetate synthesis were studied and maximum conversion was achieved at 16 % (by mass per volume) of immobilized lipase, 40 °C and 200 rpm. Under these conditions, 8-hour reaction time was sufficient to reach a high ester conversion of 95 % with 0.5 mol/L of isoamyl alcohol. The structure of the transesterified product was confirmed by infrared and nuclear magnetic resonance spectroscopic studies. Immobilized lipase had K_m and v_max values of 306.53 mmol/L and 99 μmol/(h·g) respectively, for isoamyl acetate synthesis in a solvent-free system.

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