Optimisation of alkaline pretreatment conditions of orange and plantain peels for polygalacturonase production by Aspergillus awamori CICC 2040

This study investigated the optimisation of alkaline pretreatment of orange and plantain peels for polygalacturonase (PG) production by Aspergillus awamori CICC 2040 using response surface methodology. The factors evaluated were particle size, PS (< 0.4250, 0.4250 < PS < 0.8025 and 0.8025 < PS < 1.1800 mm), NaOH molarity (0.010, 0.055, and 0.100 M), and time (1.0, 6.5, and 12.0 h). These factors were interacted to determine the most suitable combinations for maximum polygalacturonase activity (MPA). The pretreated orange and plantain peel powders were inoculated with 106 spores/mL Aspergillus awamori CICC 2040 was incubated at 28 oC for 5 days, and crude PG was extracted and its activity determined. The alkaline pretreatment combinations that gave MPA were <0.4250 mm, 0.100 M, and 1.0 h, and 0.8025 < PS < 1.1800 mm, 0.010 M, and 1.0 h for orange and plantain peel powders, respectively. The MPA obtained from the pretreated orange and plantain peel powders were 38.46 and 38.82 U/mL, respectively. Optimised alkaline pretreatment conditions of the orange and plantain peels for MPA, produced by Aspergillus awamori CICC 2040, were established. Keywords: Aspergillus awamori CICC 2040, Peel, Optimisation, Polygalacturonase, Pretreatment