Extraction and Valorization of Citrus sinensis, Citrus reticulata and Citrus limetta Peel Extracts

Citrus peels, often discarded as waste, are rich in bioactive compounds with antimicrobial, antioxidant, and anti-biofilm properties. This study aims to extract, analyze, and evaluate the phytochemical composition and biological efficacy—including antimicrobial, anti-biofilm, and antioxidant activities—of ethanolic citrus peel extracts from C. sinensis (Orange), C. reticulata (Mandarin), and C. limetta (Sweet Lime). On quantitative phytochemical analysis, C. sinensis peel extract had the highest phenolic (4.5 mg GAE/g) and flavonoid (2.06 mg RE/g) content and showed the strongest antioxidant activity (69.31%). It also demonstrated the highest antibacterial efficacy against S. aureus and E. coli and the maximum biofilm inhibition of 78.9% and 74.6%, respectively (p < 0.05). Beyond these bioactivities, this study uniquely provides a comparative evaluation of three citrus species under identical extraction and assay conditions and validates their biofilm inhibition via the MATH assay¬¬—an approach rarely reported. These findings highlight citrus peel extracts as sustainable, natural alternatives to synthetic preservatives, with potential applications in food, pharmaceuticals, and biomedical research.