Chitosan coating functionalized with silver nanoparticles synthesized from avocado leaves and cinnamon...

This study evaluated the synergistic efficacy of silver nanoparticles (AgNPs) and cinnamon oil, with criteria based on reducing minimum effective concentrations while maintaining or enhancing antifungal activity compared to individual treatments. The antifungal effects of AgNPs and the cinnamon oil/β-cyclodextrin complex, as well as their impact on chitosan film properties, were investigated for avocado preservation. Preservation performance was assessed through respiratory rate, pH, firmness, weight loss, skin color, total soluble solids, cell wall-degrading enzyme activity, and disease incidence in avocados infected with Aspergillus niger. AgNPs and cinnamon oil showed antifungal activity against A. niger at 62.5 ppm and 5 μL/mL, respectively. Their combination (AgNPs at 31.25 ppm with cinnamon oil at 2.5 μL/mL) exhibited a synergistic effect, reducing antifungal agent usage while maintaining efficacy. Incorporation into chitosan films altered transparency, color, and surface texture, making them rougher and uneven, while thickness remained unchanged (p > 0.05). The combined formulation (CAg_31.25CB_2.5), consisting of chitosan (1% w/v) with AgNPs (31.25 ppm) and cinnamon oil (2.5 μL/mL), significantly extended avocado shelf life, and disease incidence was completely inhibited even under artificial inoculation conditions after 8 days, compared to complete deterioration in controls. Overall, AgNPs, cinnamon oil, and chitosan acted synergistically as antifungal agents and formed a biological barrier that improved coating adhesion, delayed weight loss, pH changes, total soluble solids, and color shifts, enhanced firmness, lowered respiration rates, reduced cellulase activity, and protected avocados from pathogens during storage.