Active Flexible Films for Food Packaging: A Review

Abstract

Active food packaging is a dynamic area where the scientific community and industry have been trying to find new strategies to produce innovative packaging that is economically viable and compatible with conventional production processes. The materials used to develop active packaging can be organized into scavenging and emitting materials, and based on organic and inorganic materials. However, the incorporation of these materials in polymer-based flexible packaging is not always straightforward. The challenges to be faced are mainly related to active agents' sensitivity to high temperatures or difficulties in dispersing them in the high viscosity polymer matrix. This review provides an overview of methodologies and processes used in the production of active packaging, particularly for the production of active flexible films at the industrial level. The direct incorporation of active agents in polymer films is presented, focusing on the processing conditions and their effect on the active agent, and final application of the packaging material. Moreover, the incorporation of active agents by coating technologies and supercritical impregnation are presented. Finally, the use of carriers to help the incorporation of active agents and several methodologies is discussed. This review aims to guide academic and industrial researchers in the development of active flexible packaging, namely in the selection of the materials, methodologies, and process conditions.

Keywords: active packaging; antimicrobial film; antioxidant film; food packaging.

Figure 1

Structure of active film for active food packaging with headspace: (A) monolayer film with an active agent, (B) two-layer film with an active agent in the inner layer and (C) two-layer film with active substance immobilized or fixed on the surface of the film. (D,E) Schematic representation of active scavenging and releasing systems, respectively.

Figure 2

Schematic of a conventional extruder—single screw extruder. Reprinted from Covas, J., & Hilliou, L. (2018). Chapter 5—Production and Processing of Polymer-Based Nanocomposites. In M. Â. P. R. Cerqueira, J. M. Lagaron, L. M. P. Castro, & A. A. M. de O. S. Vicente (Eds.), Nanomaterials for Food Packaging (pp. 111–146) [10]. Copyright (2018), with permission from Elsevier.

Figure 3

Schematic of the film extrusion/co-extrusion lines: (A) blown film extrusion line and (B) cast film extrusion line. Reprinted from Covas, J., & Hilliou, L. (2018). Chapter 5—Production and Processing of Polymer-Based Nanocomposites. In M. Â. P. R. Cerqueira, J. M. Lagaron, L. M. P. Castro, & A. A. M. de O. S. Vicente (Eds.), Nanomaterials for Food Packaging (pp. 111–146) [10]. Copyright (2018), with permission from Elsevier.

Figure 4

Schematic of the (A) lamination process outside the extrusion line and (B) lamination extrusion.

Figure 5

Techniques used to apply the actives coatings: (A) brushing, (B) spraying, (C) manual coater, and (D) automatic coater (or plate stripe coater).

Figure 6

Schematic of the use of supercritical fluid carbon dioxide (CO₂) in the impregnation process during active film production.