Lactoferrin (L) and gellan gum (G) nanoparticles were produced in different biopolymer proportions through electrostatic complexation to enhance the antimicrobial properties of lactoferrin. The nanoparticles were characterized according to size, charge density, morphology and antimicrobial activity against S. aureus and E. coli, in two different broths to show the effect of the broth composition on the nanoparticle activity. The 9L:1G particles showed the highest positive zeta potential (+21.20 mV) and reduced diameter (92.03 nm) which resulted in a minimum inhibitory concentration six times smaller (0.3 mg/ml) than pure lactoferrin (2 mg/ml). However, the bacteriostatic action of nanoparticles was inhibited in the presence of divalent cations. When applied to strawberries as a coating, lactoferrin nanoparticles extended fruit shelf-life up to 6 days in the presence of carboxymethylcellulose (CMC). Therefore, lactoferrin-gellan gum complexation was proved to be a promising tool to enhance lactoferrin antimicrobial action and broaden its application as a food preserver.

Application of hydrophobic coatings, such as carnauba wax nanoemulsions, combined with natural antimicrobials, has been demonstrated to be an effective solution in extending the shelf life of fruits. The present study evaluated the effectiveness of carnauba wax nanoemulsion (CWN) coatings containing free or encapsulated with β-cyclodextrin (β-CD) essential oils of Syzigium aromaticum (CEO) and Mentha spicata (MEO) for the post-harvest conservation of papaya fruit. The chemical composition of the essential oils (EOs) was analyzed using GC-MS. Subsequently, coatings incorporating free and encapsulated EOs were prepared and applied to papaya fruit. Fruit was evaluated for post-harvest quality parameters during 15 days of storage. Clove essential oil presented as main compounds eugenol (89.73%), spearmint and carvone (68.88%), and limonene (20.34%). The observed reduction in weight loss in coated fruit can be attributed to the formation of a physical barrier provided by the coating. Compared to the control group, which experienced the highest weight loss of 24.85%, fruit coated with CWN and CWN-MEO:β-CD exhibited significantly lower weight loss percentages of only 5.78% and 7.5%, respectively. Compared to the control group, which exhibited a release of ethylene at a rate of 1.3 µg kg⁻¹ h⁻¹, fruit coated with CWN, CWN-MEO:β-CD, and CWN-MEO coatings demonstrated a lower ethylene release rate at 0.7 µg kg⁻¹ h⁻¹. Although the physical-chemical properties of papayas, including pH, Brix, titratable acidity, color, and texture, remained largely unchanged during storage with the coatings, analysis of incidence and severity of papaya post-harvest deterioration revealed that coatings containing essential oils effectively acted as antifungals in the fruit. Microscopy images showed that CWN and CWN-MEO:β-CD coatings are more uniform compared to the others. The edible coatings, especially CWN and CWN-MEO: β-CD, can act as antimicrobial coatings on papaya fruit, increasing their conservation during post-harvest storage.

The demand for tropical fruits worldwide has increased, but their short shelf life poses a challenge. Lychee, a highly perishable fruit used in various ways, lacks effective post-harvest preservation methods, particularly for export. To address this, plant-based edible coatings incorporating nanotechnology and essential oils offer a sustainable solution for maintaining lychee quality. This study aimed to assess the impact of carnauba wax nanoemulsion (CWN) coatings at different concentrations, with or without essential oils of Syzygium aromaticum (CEO) and Mentha piperita (MEO), on lychee preservation after harvesting. Two stages were conducted: first, determining the optimal CWN concentration (4.5%, 9%, and 18%) for storing lychee at 16 °C and 70% relative humidity for five days; second, selecting the 9% CWN concentration with 1% CEO and MEO for storing lychee for eight days under the same conditions. Physical and chemical analyses were performed during storage. GC-MS analysis showed that eugenol (89.73%) and isomenthol (49.46%) were the main components of clove essential oil and peppermint oil, respectively. The treatments with CWN (9%) and CWN (18%) significantly reduced weight loss by approximately 4% compared to the control while maintaining quality indicators such as L* value, pH, and total soluble solids (TSS%). Lychee fruits coated with CWN (9%) combined with CEO and MEO showed a significant reduction in decay incidence and severity after 168 h of storage. Specifically, the CWN–MEO treatment exhibited a 20% incidence and severity compared to the control's 60% and 100%, respectively. Coatings with 9% CWN and 1% MEO have the potential to effectively preserve post-harvest lychee quality, minimize losses, reduce disease severity, extend shelf life, and enhance commercial opportunities.