Biofunctional features of Pickering emulsified film from citrus peel pectin/limonene oil/nanocrystalline cellulose

The application of edible films can be an alternative solution for maintaining the quality of post-harvest horticultural commodities. This study aimed to determine the effect of adding a stabiliser, cellulose nanocrystals (CNCs), on the functional characteristics of citrus peel pectin and limonene essential oil (LEO)-based coatings. A formulation comprising pectin (0.5%), CNC (0.075%) and LEO (0.5%) was prepared. The CNC morphology (nanometre scale) was nanorods with pointed ends on both sides, revealed with atomic force microscopy. Gas chromatography–mass-spectrometry verified the main component of LEO, d-limonene. All prepared film-forming solution showed good stability with zeta potential values ranging from −76.34 to −35.33 mV. The developed film had a rougher surface due to the presence of oil aggregates and CNC agglomeration during film preparation. The addition of Pickering emulsion showed improvements in terms of mechanical properties (tensile strength 23.61 MPa, and elongation 65.87%), water barrier and the film clarity compared with regular emulsions with synthetic surfactants. It effectively inhibited the growth of harmful microbes that cause the rotting of fresh fruits, i.e., Penicilium digitatum, by 3.87% and 14.83% compared to the conventional emulsion and pectin-based film, respectively, through the well diffusion test method. Thus, the combination of pectin/CNC/LEO can be used as an alternative active coating for fresh fruit commodities.