Reusable nanobiocatalysts for the efficient extraction of pigments from orange peel

Nagpur mandarin orange (Citrus reticulata) peels were subjected to treatment with nanobiocatalysts in the form of cellulase and pectinase immobilized magnetic nanoparticles (MNPs). MNPs (Fe₃O₄) with average diameter in range of 40-90 nm were immobilized with cellulase and pectinase through APTES and glutaraldehyde. Treatment followed by extraction into organic solvents resulted in 8-9 fold increase in extraction of carotenoidic pigments compared to use of free enzymes. Optimum pH and temperature for the process were determined to be 5.0 and 50 °C, respectively. The nanobiocatalysts could be reused across three cycles with only 15 % drop in yield per cycle. Dinitrosalicylic acid assays showed that superior peel hydrolysis also led to greatest extent of pigment extraction.