Comparative Analysis of Antioxidant and Antimicrobial Properties of Banana and Lime Fruit Peel Extracts

Fruit peels generated during food processing are generally considered as waste and are not further utilized. However, studies conducted on fruit peels have revealed the presence of constituents that could be used for pharmacological or pharmaceutical applications. To evaluate the potential of extracting such health promoting bioactive materials from fruit peels, current study was aimed to determine the polyphenolic content and the antioxidative and antimicrobial activities of methanolic peel extracts of four local banana (Musa sapientum) varieties (Ambul, Anamalu, Seeni and Kolikuttu) and lime (Citrus aurantifolia).The Folin-Ciocalteu method was employed to calculate the total phenolic content, and antioxidant capacity was assessed with DPPH, ABTS ·+ and TBARS assays. The antimicrobial efficacy was determined using agar well diffusion method against Staphylococcus aureus and Escherichia coli. According to the results, lime and Anamalu banana peel exhibited the highest total phenolic content (178.30 ±2.46 μg GAE/ml, 120.27±0.89 μg AAE/ml and 177.87±3.68 μg GAE/ml, 102.11±1.35 μg AAE/ml respectively). All fruit peel extracts showed high scavenging effects on DPPH and ABTS+ radicals with IC50 values ranging from 51.51%±0.76 to 54.65%±0.11 and 51.56%±0.35 to 67.14%±1.38 respectively. Lime and Ambul banana showed the lowest total TBARS content. All tested banana peel extracts showed no antimicrobial activity while the absolute lime peel extracts showed a high zone of inhibition (1.9±0.0 cm) against E. coli and (1.8±0.1 cm) S. aureus. Current study provides the initial evidence of having antioxidant and antimicrobial properties in banana and lime peel. Thus, a potential exists to extract the bioactive materials responsible for such properties focusing possible applications.