Ecosynthesis of functionalized nanostructures from food sources and assessment of their bioactivities in food products

This work investigated the potential of pomace extract from sour cherries (Prunes cerasus L.) as a reducing agent to synthesize the silver nanoparticles (AgNPs). The ecosynthesis process was optimized by modifying factors including pH (5-8.5) of the reaction mixture, reaction time (1-35 min), and temperature (55-90) °C. These parameters can influence the size, shape, and stability of the synthesized AgNPs. The smallest nanoparticle size distribution was found to be 58 nm for S6 which has revealed a distinct peak at a wavelength of (464) nm with (0.94) absorption value and the optimal temperature for extraction was determined to be 80°C with pH 7.5 after 30 min of reaction time, although this sample was characterized and it was chosen for synthesizing nanocomposite film. The deposition of starch film by combining glycerol, polyethylene glycol, and starch-AgNPs at varying concentrations (1, 2, 3, and 4% of AgNPs) with starch film as a control. Starch-Ag nanocomposite (St-AgNC) films were specifically fabricated for the purpose of packing strawberries and mushrooms at a temperature of 4°C. Properties of the composite films were analyzed using FTIR, XRD, SEM, and UV-vis spectroscopy. FTIR analysis revealed a change in the structure of the starch after blending with glycerol and AgNPs. By including AgNPs, the flexibility of the composite film was enhanced. According to the scanning electron microscopy (SEM) findings, the composite films containing 4% AgNPs exhibited a flat surface. The St-AgNC films exhibited substantial antibacterial efficacy against Staphylococcus aureus, Escherichia coli, and Candida albicans organisms. The results demonstrated that nanocomposite film (S4) which contain 4% of AgNPs displayed the highest inhibition zone against S. aureus, E. coli, and C. albicans as 23.43 ± 2.05, 20.65 ± 1.74, and 15.82 ± 1.23 mm, respectively. The maximum radical scavenging activity (90.7%) was achieved in 20 min for AgNPs in a St-AgNC film containing 3 and 4% AgNPs which demonstrates AgNP's effective antioxidant ability. The findings demonstrated that the thickness of nanocomposite films comprising 1, 2, 3, and 4% AgNPs and StNC rose significantly with the increasing level of starch, measured as 0.25, 0.22, 0.20, 0.18, and 0.35 mm, respectively. The colorimetric data indicate that, the inclusion of AgNPs greatly influences the color characteristics of the St-AgNC films, whereas the inclusion of starch does not affect the pigmentation of the resultant St-AgNC films. The brightness parameter L* exhibited a negative correlation with the concentration of AgNPs. The influence of packaging on the quality and shelf life of packaged foods, including strawberries, and mushrooms, during storage, as well as the effect time on pH and microbiological development over a 14-day storage period, was evaluated using weight loss methodology. The findings suggest that the impact of 4°C storage, coating techniques significantly reduced loss in weight for treated strawberries and mushrooms compared to uncoated samples. The results show that strawberry samples (3B4, 4B4) and mushroom samples (3C4, 4C4) were coated by St-AgNC contain 3% and 4% of AgNPs respectively have a good effect on prolonging the freshness and shelf life of packaged items such as strawberries, and mushrooms in both quality and appearance after 14 days of storage. This study is the first research in the context of using pulp extract of sour cherries (Prunus cerasus L.) to synthesize the AgNPs.