Impregnation of Pectin–Sodium Caseinate Films with Lemongrass Essential Oil: Physical-Chemical, Antimicrobial, and Antioxidant Assessment

Abstract

Biopolymers derived from natural resources have gained much interest in the past few decades to replace conventional nonbiodegradable petroleum-based packaging. Essential oils and plant extracts are frequently utilized for their antimicrobial and antioxidant properties in the development of edible films and coatings serving as bioactive compounds. The current study investigated the impact of various concentrations of lemongrass essential oil (LEO) on the physical and chemical characteristics as well as the antioxidant capabilities of films made from sodium caseinate and pectin. The addition of LEO led to a decrease in mechanical parameters of film samples like elongation at break (EAB) decreased from 19.73 ± 0.81 to 4.06 ± 0.20 and tensile strength (TS) decreased from 11.16 ± 0.81 to 2.43 ± 0.08 but a rise in opacity (4.39 ± 0.14 to 5.60 ± 0.13), thickness (0.044 ± 0.005 to 0.078 ± 0.005), and water vapor permeability (WVP) (0.391 ± 0.013 to 0.760 ± 0.035) was observed. The gloss value of the film samples increased from 11.9 ± 0.1 to 13.1 ± 0.1, and haziness increased from 45.85 ± 1.05 to 71.69 ± 0.25 as the concentration of LEO increased, reducing their transparency (89.22 ± 0.27–88.24 ± 0.19). Scanning electron microscopy (SEM) revealed additional microstructural alterations in the films as a result of the addition of LEO. Furthermore, antimicrobial activity was detected in the PSC4 film sample against E. coli. The oil-loaded films showed significantly higher antioxidant activity of 40.41% compared to the control film sample, having 16.57% antioxidant activity. Contact angle measurements demonstrated that the film samples became more hydrophobic with the addition of LEO (55.52° in the maximum LEO concentrated film). This study introduces a promising method for creating active food packaging materials for packaging applications.