Lactoferrin-Chitosan-TPP Nanoparticles: Antibacterial Action and Extension of Strawberry Shelf-Life

The aim of the present study was to produce lactoferrin (L) and chitosan (C) nanoparticles by ionic cross-linking with TPP and thereby increase the antimicrobial activity of biopolymers. The nanoparticles were synthesized in different proportions of biopolymers and TPP and characterized regarding their size, zeta potential, morphology, chemical interactions, structural characteristics, and antibacterial activity. They were also applied as coatings on strawberries with the aim of increasing fruit shelf-life. Circular dichroism spectra revealed that the addition of TPP altered the secondary structure of lactoferrin. The nanoparticles 3.5L:5.5C:1TPP and 4.5L:4.5C:1TPP showed higher zeta potential values and lower hydrodynamic diameters (+39.30 mV, 81.87 nm and +33.07 mV, 97.67 nm, respectively) and intense bacteriostatic action against S. aureus (0.0370 mg/ml and 0.0463 mg/ml, respectively). The minimum inhibitory concentration of these nanoparticles was three times lower than those of pure biopolymers. When applied to strawberries coating, the nanoparticles delayed the ripening and degradation of the fruit. These results confirm that it is possible to intensify the antimicrobial properties of lactoferrin and chitosan through ionic cross-linking with TPP and, thus, expand their use as natural food preservatives.

Automated summary

The aim of this study was to enhance the antimicrobial activity of lactoferrin and chitosan by producing nanoparticles through ionic cross-linking with TPP. The nanoparticles were synthesized in varying proportions and characterized for size, zeta potential, morphology, chemical interactions, structure, and antibacterial properties. The nanoparticles with higher zeta potential values and lower hydrodynamic diameters showed strong bacteriostatic action against S. aureus and delayed the ripening and degradation of strawberries when applied as coatings. These findings highlight the potential of these nanoparticles as natural food preservatives.