Synthesis of Gelidium amansii polysaccharide-stabilized silver nanoparticles and their application for strawberry preservation in polysaccharide/gelatin films.

Silver nanoparticles (AgNPs) possess excellent food preservation properties; however, their tendency to aggregate limits this functionality. Polysaccharides can potentially stabilize AgNPs. In this study, AgNPs were synthesized with an acidic polysaccharide extracted from Gelidium amansii (GAP), and their performance in strawberry preservation was evaluated. Using a fixed 1.0 mg/mL AgNO3 concentration, two AgNPs samples were synthesized with GAP concentrations of 0.2 mg/mL (GAP-AgNPs-A) and 0.5 mg/mL (GAP-AgNPs-B). The average particle sizes of GAP-AgNPs-A and GAP-AgNPs-B were 119.20 ± 2.40 and 163.22 ± 3.33 nm, which were significantly smaller than that of pure AgNPs (852.84 ± 191.01 nm). Composite films prepared with incorporation of GAP-AgNPs into a GAP/gelatin (GEL) matrix exhibited enhanced mechanical properties, better barrier properties, and stronger antibacterial activity. The GAP-AgNPs-A/GEL and GAP-AgNPs-B/GEL films effectively extended the shelf life of strawberries, reducing decay rates to 23.01 ± 2.90% and 27.26 ± 4.89% at the tenth day of storage, respectively. The nanosilver residues in strawberries were below the European Union standard safe limit in food. This study provides an environmentally friendly method of preparing AgNPs along with an effective biodegradable film for prolonging the shelf life of fruits.