Green biosynthesized Satureja rechingeri Jamzad-Ag/poly vinyl alcohol film: quality improvement of Oncorhynchus mykiss fillet during refrigerated storage

Abstract The nanosilver food packaging films were developed by polyvinyl alcohol activated with Satureja rechingeri extract (S-AgNPs/PVA) using the solvent casting to evaluate the freshness of Oncorhynchus mykiss fillets during 14 days at the refrigerated temperature. The 160 pieces of fish were enfolded in 4 types of films as main group-series. The main components of the extract were carvacrol (83.2%) p-cymene (3.11%), thymol (2.13%) and γ-terpinene (1.63%). The UV-Vis and TEM evaluations of S-AgNPs showed that the size of S-AgNPs was mostly smaller than 55 nm in diameter. Mesophilic and psychrophilic bacteria counts were remarkably less than 6.0 log CFU/g about 2.1, 1.3 log CFU/g and 2.0, 1.0 log CFU/g, respectively for fish samples wrapped in S-AgNP/Ult.PVA (Ultrasound method) and S-AgNP/Pho.PVA (Photochemical method) preserved at 4 °C on the 7th day. S-AgNP/Ult.PVA and S-AgNP/Pho.PVA showed strong efficiency in complete eliminating S. aureus and psychrophilic bacteria from coated trout samples than E. coli and mesophiles. It is suggested that AgNP/Ult.PVA and S-AgNP/Pho.PVA films can be used as nanocomposite film for fish preservation at refrigerated temperature to postpone the spoilage up to 7th day.