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

Abstract

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.

Expanding the shelf life of chicken fillets by the use of polylactic acid (PLA) active films: An investigation of orange oil antibacterial potential

“…Light was blocked by distributed oil droplets in the film forming matrix 15 . Similar results were also mentioned in the study of Ziziphora Clinopodioides essential oil incorporated PLA films 16 . However, in another study, addition of origanum, clove, and garlic essential oil into the fish protein film matrix also did not influence the transparency of the films 17 .…”

“…As increasing film opacity decreases transmission of visible light and UV‐light, it is more desirable for a lesser level of nutritional loss and of oxidative spoilage and to maintain color and taste of food through storage period. Nevertheless, it might affect consumer perceptions 16 …”

“…15 Similar results were also mentioned in the study of Ziziphora Clinopodioides essential oil incorporated PLA films. 16 However, in another study, addition of origanum, clove, and garlic essential oil into the fish protein film matrix also did not influence the transparency of the films. 17 At the end, it can be figured out that the type of essential oil has an influence on opacity values of the films.…”

Shelf life extending of probiotic beef patties with polylactic acid‐ajwain essential oil films and stress effects on Bacillus coagulans

“…(2010), who reported soy protein‐based film incorporated with thyme and oregano EO significantly reduced the PSC of ground beef during 12 days of storage in comparison with control treatments. There are some studies who reported that the PLA films with or without EOs showed a low rate of oxygen permeability which makes microaerophilic conditions for the growth of facultative anaerobic microorganisms (Heydari‐Majd et al., 2019; Laorenza & Harnkarnsujarit, 2021; Shakour et al., 2021), but Pseudomonads as psychrotrophic and strictly aerobic bacteria which is affected by PLA packaging due to the lower oxygen permeability which was reported by Heydari‐Majd et al. (2019).…”