Effect of lactoferrin on physicochemical properties and microstructure of pullulan-based edible films

Pullulan is a polysaccharide polymer commonly used to produce edible films. However, pure pullulan film is usually brittle and very hydrophilic, which limit its use in both food and pharmaceutical fields. The objective of this research is to improve the structural and mechanical properties of pullulan film by incorporating globular protein lactoferrin (LF).

The incorporation of LF increased the surface hydrophobicity and decreased the water vapor permeability (WVP) of pullulan film. The presence of low concentrations of LF (< 0.03%) has no significant influence on tensile strength (TS) and elongation at break (EAB) of pullulan film. However, further increase of LF concentration to levels > 0.03% resulted in a film-weakening effect. LF molecules aggregated with each other during the film-producing process, which presented as spherical particles from the observation of microscopy. LF aggregates dispersed homogeneously throughout the pullulan matrix and their size increased with increasing concentration. Analysis from Fourier transform infrared spectroscopy indicated that the secondary structure of LF molecules was modified during the drying process.

It is possible to increase the hydrophobicity of pullulan film while maintaining its mechanical properties. The produced composite film can be potentially used for food and medical packaging. © 2019 Society of Chemical Industry.