Cross-linked natural IntegroPectin films from Citrus biowaste with intrinsic antimicrobial activity

Pectin recovered via hydrodynamic cavitation (IntegroPectin) from lemon and grapefruit agri-food waste intrinsically containing antimicrobial bioactive substances (flavonoids, phenolic acids, terpenes, and terpenoids) was used to generate innovative and eco-compatible films that efficiently inhibit the growth of Gram-negative pathogens. Extensive characterization of films confirmed the presence of these substances, which differently interact with the polysaccharide polymer (pectin), plasticizer (glycerol), surfactant (Tween 60), and cross-linker (Ca2+), conferring to these films a unique structure. Besides, IntegroPectin-based films constitute sustained, controlled, and slow-release (up to 72h) systems for bioactive substances in an aqueous environment. This feature is crucial for the good in vitro antimicrobial activity exerted by IntegroPectin films against three Gram-negative bacteria (two indicator pathogen strains Pseudomonas aeruginosa ATCC 10145, P. aeruginosa PAO1, and the clinical isolate Klebsiella pneumoniae) that are involved in the global emergence of the antimicrobial resistance.