Green synthesized silver nanoparticles by avocado leaves incorporating chitosan edible coating for avocado preservation under ambient conditions

Abstract

In this study, silver nanoparticles (AgNPs) synthesized from avocado leaf extract and chitosan, including chitosan (1 % w/v) with (CL samples) or without avocado leaf extract (C samples), chitosan-incorporated AgNPs (CLAg samples), and AgNPs alone were used for avocado preservation under ambient temperature. AgNPs, with an average particle size of 142.3 nm, exhibited antifungal effectiveness against Aspergillus niger at a concentration of 62.5 ppm. Incorporating AgNPs into chitosan influenced the films' transparency, color, and surface properties, resulting in a rough texture on the film's surface. However, no significant differences in firmness and thickness were observed. The preservation of avocados at ambient temperature showed that coated avocados had reduced weight loss and a slight decrease in pH value compared to control samples, although these differences were not statistically significant. Notably, there were significant differences in total soluble solids and firmness values and slower color changes in coated samples compared to uncoated ones during storage. The evaluation of damage rates in avocado fruit (infected by A. niger 5 Log CFU/ml) revealed that no damage was observed in CLAg samples. In contrast, the damage rates for the control, AgNPs, C, and CL samples after four days of storage were 48.33 %, 7 %, 13.33 %, and 8.33 %, respectively. These findings suggest that incorporating AgNPs into chitosan effectively reduces damage caused by A. niger and maintains the quality of avocado fruit during storage.