Formulation of Edible Films Based on W/O/W Emulsions Stabilized by Coffee Byproducts.

Complex emulsions are potential colloidal dispersions in formulating edible films, but these emulsions often have a low stability while their formulation is very complicated. This study, therefore, focuses on formulating water-in-oil-in-water (W/O/W) emulsions stabilized by the mixtures of biopolymers (including pectin and cellulose extracted from the coffee pulps) using the ultrasound technology. Classical techniques including a rheology analyzer, texture analyzer, and scanning electron microscopy (SEM) were applied to evaluate the stability of double emulsions and physicochemical properties of edible films. Obtained results revealed that W/O/W emulsions could be formulated from the biopolymer solutions using the ultrasound technology. These double emulsions showed a high stability, and the phase separation did not occur during 1 week of the storage at the ambient temperature. Edible films based on W/O/W emulsions have a high mechanical resistance (tensile strength of 1.3–1.8 MPa and Young's modulus of 40–50 MPa), a high melting point (120–140 °C), a low water vapor permeability (3–16 g.mm.m−2.h−1.KPa−1), and a high antioxidant capacity (2.5–4.4 kg film/mol DPPH). [ABSTRACT FROM AUTHOR]