Acetylated cashew gum polysaccharide nanoparticles as a promising green label nanomaterial for encapsulation of D-limonene: physicochemical, structural and antibacterial properties

Abstract

The prevalence of foodborne diseases caused by Gram-positive and Gram-negative bacteria has long been a common yet worrisome problem. Antibacterial preservatives based on natural molecules offer an effective and safe solution to delay or inhibit bacterial growth and reproduction, extending the self-life of food and preserving its freshness and quality. In this study, we combined acetylated natural polysaccharides from cashew gum (acCGP) and D-limonene (DL), aiming to create sustainable nanoparticles with enhanced antibacterial properties. The acCGP@DL nanoparticles were produced by nanoprecipitation and presented a smooth and spheric microstructure with a hydrodynamic diameter of 161 nm, PDI of 0,141 and zeta potential of -19.17mV. The nanosystem was able to encapsulate 75.2% of DL, presenting a loading capacity of 15.2%. Results from X-ray diffraction and differential scanning calorimetry showed that the DL encapsulation increased the crystalline nature of the acCGP@DL nanoparticles. Thermogravimetric analyses also evidenced the efficiency of the encapsulation in improving the thermostability of DL. The antibacterial potency was evaluated against the most common foodborne pathogens. Results evidenced that acCGP@DL nanoparticles showed higher antibacterial activity against Escherichia coli EPEC (CDC O55) (MIC = 14.2 mg mL^− 1 of nanoparticle; effective DL concentration of 2.2 mg mL^− 1), Salmonella enteritidis (S64) (MIC = 7.1 mg mL^− 1 of nanoparticle; effective DL concentration of 1.1 mg mL^− 1) and Staphylococcus aureus (ATCC 13565) (MIC = 14.2 mg mL^− 1 of nanoparticle; effective DL concentration of 2.2 mg mL^− 1). The SEM images of bacterial cells treated with acCGP@DL nanoparticles showed significant morphological changes, with the appearance of shallow depression, disruption of the cell membranes, and liberation of cytoplasmic content. This study underscores the potential of acetylated cashew gum polysaccharides as nanocarriers and evidence that the produced acCGP@DL nanoparticles have promising applications in diverse fields of the food industry requiring eco-friendly and high-performance components to develop bioactive coatings and packaging.