Mass Transfer and Optical Properties of Active PET/PP Food-Grade Films Impregnated with Olive Leaf Extract

Abstract

A supercritical solvent impregnation (SSI) technique was employed to incorporate, by batch- and semicontinuous-modes, bioactive olive leaf extract (OLE) into a food-grade multilayer polyethylene terephthalate/polypropylene (PET/PP) film for active food packaging applications. The inclusion of OLE in the polymer surfaces significantly modified the colour properties of the film. A correlation of 87.06% between the CIELAB colour parameters and the amount of the OLE impregnated in the film was obtained which suggests that colour determination can be used as a rapid, non-destructive technique to estimate the OLE loading in the impregnated matrices. The UV barrier and water permeability properties of the films were not significantly modified by the incorporation of OLE. The migration of OLE into a 50% (v/v) ethanol food simulant demonstrated faster release of OLE from the PP surface than from the PET surface which may be due to the different interactions between OLE and each polymer.

Keywords: CIELAB parameters; UV barrier; impregnation mode; kinetic migration; olive leaf extract; supercritical impregnation.

Figure 1

Appearance of the PET/PP films (a) before and (b) after OLE impregnation (sample corresponding to the impregnation at 400 bar and 35 °C by batch mode).

Figure 2

Dendrogram obtained from the HCA of control film and impregnated film considering the CIELAB parameters (a); CIELAB coordinates in (a*b*)-plane for control and impregnated films (b).

Figure 3

Percentage WVP of untreated PET/PP film (control) and OLE-impregnated films at (a,b) 20 °C and (c,d) 35 °C.

Figure 4

Solute release into the 50% v/v ethanol in water food simulant (a) and first order kinetics plot of solute release (b).

Figure 5

OLE diffusion of samples impregnated at 400 bar 35 °C using BM (a) and 100 bar 35 °C using SM (b) according to Fick’s law.

Figure 6

Theoretical release of OLE into food simulant.