Exploitation of Citrus Peel Waste in Solid-State Fermentation for Eco-Friendly and Cost-Effective Production of Cold-Active Pectinase by Penicillium crustosum KSA 98 and its Application in Fruit Juice Clarification

This study acquired sixty-two fungal isolates that have been assessed for their ability to produce pectinase at 10 °C. The powerful strain was recognized as Penicillium crustosum KSA 98 using sequencing of its internal transcribed spacer region (ITS). P. crustosum KSA 98, utilizing orange peels in solid-state fermentation (SSF), generated the highest pectinase at pH 6 and 10 °C after 14 days, with beef extract as the nitrogen source, with an enzyme activity of 254.4 U/gram dry substrate (gds). The pectinase was concentrated utilizing 70% ammonium sulfate, and then dialysed with a 12-14 kD cutoff dialysis tube. The purified pectinase had maximum activity of 60±4.8 U/mg at pH 6 and 25 °C. Except for Mn²⁺, EDTA, along with Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺, Cu²⁺, Fe²⁺, Ni²⁺, Co²⁺, and SDS, had significant inhibitory effects on pectinase activity. The pectinase was employed in the processing of apple and orange juice. The results demonstrated that juice yields for apple and orange rose by 22.7% and 24.62%, while juice clarity enhanced by 35.44% and 53.84%, respectively. Furthermore, there was a 25.0% and 29.77% improvement in the juice's color, respectively.