Kinetic and thermodynamic investigations of cell-wall degrading enzymes produced by Aureobasidium pullulans via induction with orange peels: application in lycopene extraction

Abstract

The production of cell-wall degrading enzymes (CWDE) such as cellulase and pectinase by Aureobasidium pullulans NAC8 through induction using orange peels was investigated for the potential application of these enzymes in the extraction of lycopene from tomato skin, waste, and paste (SWP). The CWDE was then immobilized via entrapment in alginate beads for lycopene extraction and the kinetic/thermodynamic properties of the free and immobilized CWDE investigated. The optimum production of CWDE occurred at pH, temperature, and orange peel concentration of 6.0, 50 °C, and 2.0% (w/v), respectively. The values obtained for some kinetic and thermodynamic parameters such as $E_d^{\mathrm{*}},$ $t_{1/2},$ ${\Delta G}_d^{\mathrm{*}},$ and ${\Delta H}_d^{\mathrm{*}}$ indicate that both free and immobilized cellulase and pectinase were thermostable between 40 and 50 °C. Maximum lycopene extracted from the tomato SWP was 80 ± 2.4 mg/kg, 42 ± 1.3 mg/kg and 60 ± 1.2 mg/kg, respectively, using the immobilized CWDE. The entrapped CWDE was able to extract lycopene with yields of 58 ± 4.2, 51 ± 1.2 and 57 ± 4.2% for tomato SWP respectively after the fifth cycle. Using orange peels for the induction of CWDE by A. pullulans offers a unique and cheaper approach to obtaining thermostable multi-enzyme complexes employable for easy lycopene extraction from tomato SWP.

Keywords:

• Cellulase
• pectinase
• lycopene
• submerged fermentation
• Aureobasidium pullulans NAC8
• orange peel
• tomatoes

Disclosure statement

No potential conflict of interest was reported by the authors.