Mosambi (Citrus limetta) peel upcycling: valorization strategies for food and non-food applications in the circular bioeconomy

Mosambi (Citrus limetta) peel is a prolific yet underutilized agro-industrial by-product, constituting approximately 38–43% of the fruit’s total weight. It represents a rich reservoir of dietary fiber, pectin, essential oils, and polyphenols, but remains largely overlooked in valorization strategies. Although citrus waste has been widely studied, a feedstock-specific synthesis focused on C. limetta is notably absent, representing a critical gap in the literature. This review presents a comprehensive and critical synthesis of recent advances in mosambi peel valorization, emphasizing its compositional characteristics, extraction technologies, mechanistic insights into its bioactivities, and multi-sectoral applications. It offers the first integrated evaluation of C. limetta peel and establishes a cohesive framework that links its distinctive biochemical profile, particularly its abundance of specific flavanone glycosides and D-limonene, to advanced extraction techniques and downstream utilization pathways. Analytical evaluation indicates that green extraction methods, including microwave-assisted extraction and ultrasound-assisted extraction, enhance the recovery of pectin and polyphenols by over 30%. However, a key trade-off emerges between extraction intensity and the preservation of bioactive compound integrity. High-methoxyl pectin with a degree of esterification greater than 60% and essential oils rich in D-limonene above 85% exhibit superior functional performance, particularly in active packaging systems and as natural antimicrobials against foodborne pathogens. Additionally, hydrothermal processing is identified as a thermodynamically favorable pathway for wet biomass conversion, as it circumvents the energy-intensive drying stages associated with conventional pyrolysis. The study concludes that mosambi peel is not merely a waste management challenge but a strategic biorefinery feedstock. However, the transition from laboratory success to industrial implementation is currently hindered by a lack of techno-economic and life cycle assessments. Future research must prioritize standardized cascading biorefinery models to ensure economic viability and environmental sustainability in the circular bioeconomy.