Comparative antibacterial and antioxidant in vitro activities of edible (pulp) and non-edible (peel) parts of unripe banana fruit were investigated. Peels and pulps of fruit were extracted using methanol and acetone separately. Antibacterial property of these extracts was evaluated against four species of multiple drug resistant (MDR) bacteria namely Escherichia coli, Klebsiella sp, Salmonella sp. and Shigella sp. using disc diffusion technique. When compared between pulp and peel on the basis of zone of inhibition created by them, pulp and peel exhibited 14.5 mm and 16.2 mm, respectively, whereas the standard drug, Kanamycine (30µg/disc) showed >30mm. In case of MIC, pulp was ranged from 200-300 mg/ml, while peel was from 200-250 mg/ml. As like MIC, MBC also found better in peel (400-550 mg/ml) than pulp (450-600 mg/ml). Results showed that non-edible part was better than edible part for controlling bacteria. Antioxidant activity of the extracts was evaluated by total phenolic content determination and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. DPPH scavenging activities of non-edible part (70.62%) was found higher than edible part (54.79%), while 100% was observed by ascorbic acid at same concentration (100μg/ml). In case of phenol content, edible part of banana showed lower phenolic content (71.49 mgL-1 GAE / g dry material) than non-edible part (92.76 mgL-1 GAE / g dry material). Comparing between pulp and peel, peel found better than pulp in every case, e.g., antibacterial (both MIC and MBC), antioxidant activities and total phenol content. The results suggest that banana peels could serve as potential source of bioactive compounds and can be utilized effectively without being wasted.
A 2020 study studied this question.