Phenolic compounds and antioxidants activity of banana peel extracts: Testing and optimization of enzyme-assisted conditions

Banana processing industry generates a large number of by-products mainly constituted by peel that can be a good source of bioactive polyphenols. Extraction of phenolic compounds using optimum extraction conditions enhances the yield and quality of the desired compounds. Meanwhile, a well-chosen optimization procedure has the ability to reduce the amount of time, solvent, and temperature needed, which will consequently lower the overall process cost. In this study, the optimization of the enzyme-assisted extraction conditions was evaluated for the maximum extraction of phenolic compounds from banana peels using three enzymes viscozyme® L, cellulase, and pectinase. The optimum conditions were achieved using enzyme concentration (0–2%, v/v), extraction time (1–12 hrs), extraction temperature (35–60 °C), and the solute-liquid ratio (1:5–1:30, w/v) at pH 4.0. The responses such as total phenol content (TPC), total flavonoid content (TFC), DPPH and ABTS inhibition activity, and α-glucosidase inhibitory activity were determined by spectrophotometric analysis. Viscozyme® L was found more effective compared to cellulase, and pectinase, and the optimum condition was obtained with 1.0% enzyme concentration, 9 hrs extraction time, 55 °C extraction temperature, and the solute-liquid ratio 1:25. The values of TPC, TFC, DPPH and ABTS, and α-glucosidase inhibitory activity at optimized condition were 25.37 mg GAE/g DM, 13.99 mg QE/g DM, 81.59%, 88.25%, and 74.67% scavenging ability, respectively. Therefore, viscozyme-assisted extraction could be a promising method for phenolic compounds from banana peels and the utilization of banana peels as valuable ingredients for food and pharmaceuticals.