Valorization of Pineapple Processing Wastes via Non-Conventional Extraction of Bioactives for Antimicrobial Application

Pineapple peel, a significant byproduct of the pineapple processing industry, contains abundant bioactive compounds with notable antioxidant and antimicrobial properties. This study compares the efficiency of conventional and non-conventional extraction methods, including solvent extraction (SE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) for recovering phenolic compounds from pineapple peel waste. Methanol, ethanol, and acetone were evaluated as extraction solvents. The resulting extracts were characterized for total phenolic content (TPC), antioxidant capacity (DPPH and FRAP assays), and antimicrobial activity against Escherichia coli . MAE with ethanol yielded the highest TPC (1.26 µg GAE/g), while UAE with methanol demonstrated the strongest FRAP activity (37.75 mmol TE/g). Notably, SE-methanol and UAE-methanol extracts exhibited the highest antimicrobial activity, with inhibition zones reaching 6.0 mm. The findings underscore the significant influence of both solvent type and extraction method on extract yield and bioactivity. Non-conventional techniques, particularly MAE and UAE, showed enhanced performance compared to SE, indicating their potential for the sustainable valorization of pineapple peel waste into high-value antioxidant and antimicrobial agents suitable for food or pharmaceutical applications.