Assessment of antimicrobial potential of polyphenol-rich Ananas comosus peel powder at different drying conditions

The main objective of present study is to focus on recycling of pineapple waste by estimating its antimicrobial potential against selected pathogenic strains. Four drying techniques, hot air oven (S1), microwave (S2), sun (S3), and freeze (S4), were applied to dry the peels. Methanol, acetone, and water, were used as solvent for extract preparation. Then these extracts were evaluated for antimicrobial activity against 3 fungal, 6 Gram-negative and 2 Gram-positive strains through agar well diffusion and broth dilution methods. Further, HPLC and TLC bioautography method was applied to reveal phytochemicals responsible for antimicrobial activity. Methanolic extract of S1 sample has shown the best zone of inhibition (23±0.014 mm) against Pseudomonas fluorescens strain. In gram-positive strains maximum zone (25±0.014 mm) was noted against Staphylococcus aureus and in fungal strains, maximum zone (22 mm) was observed against Fusarium sp. and Tilletia indica with lowest MIC (12.24 mg/mL) and LD50 value were calculated against Bacillus megaterium. Quantitative analysis through HPLC shows highest concentration of Bromelain in pineapple peel, along with the presence of ellagic acid, ferulic acid, catechin, caffeic acid, and gallic acid. Results of this study show the highest antimicrobial potential of pineapple peel for use in the pharmaceutical or neutraceutical industry.