Investigating the properties of PLA‐nanochitosan composite films containing Ziziphora Clinopodioides essential oil and their impacts on oxidative spoilage of Oncorhynchus mykiss fillets

• Published in: Food science & nutrition 2021-03, Vol.9 (3), p.1299-1311
• Main Authors: Shakour, Nastaran, Khoshkhoo, Zhaleh, Akhondzadeh Basti, Afshin, Khanjari, Ali, Mahasti Shotorbani, Peyman
• Format: Article
• Language: English
• Subjects: active packaging; Antioxidants; Chemical analysis; Elongation; Essential oils; Fillets; Fish; Fisheries; Fishery products; Food; Food packaging; Food quality; mechanical characteristics; Mechanical properties; Mechanical tests; Moisture content; Nanoparticles; Nitrogen; Oncorhynchus mykiss; Original Research; Oxidation; Packaging; Permeability; Physical characteristics; Physical properties; Physical tests; Polylactic acid; Polymers; Porosity; rainbow trout fillets; Refrigeration; Salmon; Scanning electron microscopy; Spoilage; Tensile strength; Trout; Turbidity; Water content; Water vapor
• ISSN: 2048-7177; 2048-7177
• DOI: 10.1002/fsn3.2053

The present study aimed to investigate the impact of polylactic acid (PLA) integrated with nanochitosan (NC) composite film and Ziziphora Clinopodioides essential oil (ZCEO) on oxidative spoilage of rainbow trout fillets during a 9‐day refrigeration period. For this purpose, first, six degradable films including T1: PLA, T2: PLA + NC, T3: PLA + NC + 1% ZCEO, T4: PLA + NC + 1.5% ZCEO, T5: PLA + 1% ZCEO, and T6: PLA + 1.5% ZCEO were prepared. Next, the properties of the films were investigated. The results of the mechanical tests showed that ZCEO decreased the tensile strength and increased the elongation at the break of the PLA films. However, adding NC improved the mechanical characteristics of the PLA film. The outcomes of physical tests including moisture content (14.02%), solubility (17.41%), water vapor permeability (1.14 × 10−7 g s−1 m−1 Pa−1), and oxygen transmission rate (21.54 cm3.mm/m2.24 hr) showed that adding 1% ZCEO improved the film physical characteristics. Nevertheless, by adding 1.5% concentration EO to the PLA film, the values of water vapor permeability, porosity (according to the scanning electron microscopy), and turbidity increased and cross‐sectional pores were observed. Moreover, the films had high antioxidant properties (84.33%). In the next step, the effects of the mentioned films on the oxidative spoilage of rainbow trout fillets were investigated. The results of the chemical analysis in PLA film with the EO compared with the control treatment revealed the increasing trend of oxidation indices, in general. Moreover, increasing the concentration yielded better results such that all treatments containing EO showed satisfactory results up until the storage period ends. In most cases, adding NC affected the mentioned characteristics positively, and the best results were observed in T4 and then in T3. However, based on economics and the better mechanical and physical properties of T3, the film can be applied as an active packaging in fishery products. Rainbow trout is one of the fish widely consumed in Iran and the world. Moreover, fresh fish have a shorter shelf life and are considered as highly vulnerable foods compared to other meat products. Hence, it is essential and beneficial to use proper substances with antioxidant and antibacterial activity to improve the quality and enhance the fish shelf life. The results of this study about the quality of fish fillets indicated that the composite film of PLA‐NC with ZCEO decelerated the in