Konjac glucomannan-based composite films fabricated in the presence of carnauba wax emulsion: hydrophobicity, mechanical and microstructural properties evaluation.

Abstract

Despite the excellent characteristics of carnauba wax (CW), hydrophobicity in particular, its complementary effect on the enhancement of konjac glucomannan (KGM) films remains poorly documented. KGM is a promising food bio-packaging material with excellent film-forming abilities, which could be improved further through modification of its hydrophilic nature using CW. In this study, emulsified composite films (KW) of KGM incorporated with varied CW concentration levels (0%, 4%, 8%, 12%, 16% and 20% w/w) were successfully prepared by solvent casting method. Increasing CW in KW films significantly improved the hydrophobicity, barrier and mechanical properties. The recorded improvements in functional properties relative to KGM films include fivefold solubility reduction, twofold contact angle and strength increment, as well as significant increase in stretch (61%) and decrease in water vapour transmission rate (48%). Microstructure analyses using scanning electron microscopy demonstrated remarkable improvements in cohesiveness, smoothness and homogeneity in KW aggregates with higher CW concentrations. Generally, our findings reveal the potential use of KW films as food packaging material which could reduce the availability of unsafe and environmentally unfriendly food packages in the market.