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.摘要 本研究采用溶剂浇铸法，以雷氏风轮菜（Satureja rechingeri）提取物活化的聚乙烯醇（polyvinyl alcohol, PVA）制备载银纳米颗粒复合薄膜（S-AgNPs/PVA），用于评估虹鳟（Oncorhynchus mykiss）鱼片在冷藏条件下14天内的新鲜度。实验将160份鱼样分为4组，分别采用4种薄膜进行包裹。该提取物的主要成分为香芹酚（83.2%）、对伞花烃（3.11%）、百里香酚（2.13%）与γ-松油烯（1.63%）。对S-AgNPs的紫外-可见光谱（UV-Vis）与透射电镜（TEM）表征结果显示，所制备的银纳米颗粒直径大多小于55 nm。在4℃冷藏条件下，第7天时，经超声法制备的S-AgNP/Ult.PVA薄膜与光化学法制备的S-AgNP/Pho.PVA薄膜包裹的鱼样，其嗜温菌与嗜冷菌菌落数分别约为2.1、1.3 log CFU/g与2.0、1.0 log CFU/g，显著低于6.0 log CFU/g的限值。相较于大肠杆菌（E. coli）与嗜温菌，S-AgNP/Ult.PVA与S-AgNP/Pho.PVA薄膜可更高效地完全清除包裹虹鳟样品中的金黄色葡萄球菌（S. aureus）与嗜冷菌。研究表明，S-AgNP/Ult.PVA与S-AgNP/Pho.PVA纳米复合薄膜可应用于冷藏条件下的鱼类保鲜，将腐败进程延迟至第7天。