Fermented Fruit Peels for Sustainable Biotechnological Applications

Abstract

A new and environmentally viable approach towards recycling fruit waste is the valorisation through fermentation that could yields a multipurpose liquid called eco-enzyme (EE) or garbage enzyme. This study aimed to provide an insight on the multienzyme, antibacterial and antioxidant potentials of fermented fruit peels solutions produced using pineapple, orange, and watermelon peels. To achieve this, each of the pineapple, orange, and watermelon peels were fermented individually by mixing with water and brown sugar in a ratio of 3:1:10 (fruit peel: brown sugar: water) for 3 months. After 3 months of fermentation, the solutions were filtered and evaluated for their enzymatic, antibacterial, and antioxidant attributes. All the Eco-enzyme solutions exhibited amylase, cellulase, pectinase and protease enzyme activities. Also, all the eco-enzyme solutions inhibited the growth of all the test bacteria, with pineapple peel-derived eco-enzyme solution being the most active in inhibiting the growth of all the tested bacterial strains. All the eco-enzyme solutions produced in this study, showed strong antioxidant properties of 73.21%, 69.37%, 60.09%, and 82.71 for pineapple peels eco-enzyme solution, orange peel eco-enzyme solution, watermelon peels eco-enzyme solution, and mixed fruit peels eco-enzyme solution respectively at 100 ppm. Mixed fruit peels eco-enzyme solution showed the highest amylase activity of 38.75 U/mL, orange peel eco-enzyme has the highest cellulase and pectinase activities of 61.26 U/mL and 62.15 U/mL respectively. Pineapple peel eco-enzyme has the highest protease activity of 79.29 U/mL. Also, all the eco-enzyme solutions inhibited the growth of all the test bacteria, with Staphylococcus aureus exhibiting more sensitivity to all the eco-enzyme solutions compared to other tested bacterial strains. The zone of inhibitions observed against Staphylococcus aureus 18±0.12, 21±0.23, and 19±0.15 for pineapple peels eco-enzyme solution, orange peel eco-enzyme solution, and watermelon peels eco-enzyme solution respectively. The fermented solutions exhibited multienzyme potentials, broad-spectrum antibacterial potential, and significant antioxidant activities. These results suggest that solutions from fermented pineapple, orange, and watermelon peels are interesting areas for further research due to their exhibited attributes.