Development of biocomposite films incorporated with different amounts of shellac, emulsifier, and surfactant

This study examined the effects of different ratios of shellac (20–60%), stearic acid (SA) (0–2%), and Tween-20 (0.1–0.5 ml) on the water vapor permeability (WVP) and mechanical properties of the pea starch-guar gum (PSGG) films which were evaluated by using response surface methodology (RSM). The incorporation of shellac into the PSGG film structure led to a slightly increased of film thickness. However the addition of higher concentrations of shellac did not improve the moisture barrier of PSGG film owing to the poor distribution of shellac in the film structure. Film formulated with 40% shellac, 1% SA, and 0.3% Tween-20 exhibited optimal functional properties. Moreover, the influence of the incorporation of different emulsifiers into the optimized film matrix was investigated by studying the physical, mechanical, and optical properties of the films. Films containing oleic acid (OA) showed not only lower thickness, WVP, moisture content, and water solubility, but also higher percentage of elongation (E), tensile strength (TS), and transparency compared with other fatty acids tested. Biocomposite pea starch-guar gum-shellac (PSGG-Sh) films containing OA can be considered to be sufficient for most of food packaging applications.