Development and Evaluation of a Novel-Thymol@Natural-Zeolite/Low-Density-Polyethylene Active Packaging Film: Applications for Pork Fillets Preservation

Sustainability, the circular economy, and the greenhouse effect have led the food packaging industry to use naturally available bio-compounds. The integration of such compounds in packaging films increases food safety and extends food shelf-life. The development of an active/antioxidant packaging film based on the widely commercially used low-density polyethylene, natural zeolite, and Thymol, a natural extract from thyme oil, is presented in this work. The obtained active films were characterized using X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy, and Differential Scanning Calorimetry techniques. The tensile strength, water-oxygen barrier properties, and total antioxidant activity were measured. Low-density polyethylene incorporated with Thymol@Natural Zeolite at a proportion of 15 wt% was the most promising material and was used as film to wrap-up pork fillets. The thiobarbituric acid (TBA) method and heme iron measurements indicated a delayed lipids oxidation using this film. A linear correlation between the TBA method and heme iron values seems to be established, which could result in a fast method to determine the degree of lipid oxidation in pork fillets. Finally, a two-stage diffusion process during Thymol release was observed, and the values of the diffusion coefficient was 2.09 x 10(-7) and 1.21 x 10(-8) cm(2)/s for each stage. The applied pseudo-second sorption model provided a rate constant k(2) = 0.01647 (s(-1)). These results indicate the strong potential of such films to be used as food packaging materials free of E-number preservatives.

Automated summary

Sustainability and the circular economy have driven the food packaging industry to use naturally available bio-compounds, leading to increased food safety and extended shelf-life. This study presents the development of an active/antioxidant packaging film using low-density polyethylene, natural zeolite, and Thymol. The active films showed promising results, effectively delaying lipid oxidation in pork fillets. The diffusion process of Thymol release was observed to have two stages, and the films have potential as E-number preservative-free food packaging materials.