Complexed Biopolymer of Whey Protein and Carboxymethyl Cellulose to Enhance the Chemical Stability of Lemon Oil-in-Water Emulsions

Abstract

Lemon oil (LO) has been used as a flavoring food additive and its encapsulation in emulsions has facilitated its incorporation in food and pharmaceutical products. d-Limonene, the main ingredient in LO, and citral, the compound responsible for the aromatic profile, are easily oxidized and a new emulsion interfacial structure is needed to protect these compounds. This paper studies the physical and chemical stabilities of LO-in-water emulsions produced by membrane emulsification as a function of the oil droplets’ surface electric charge and interfacial thickness. For that purpose, the different stabilizers used were whey protein (pH: 3.8 and 6.8), and, for the first time in lemon oil encapsulation, an electrostatic whey protein-carboxymethyl cellulose (WP-CMC) complex (pH: 3.8). Although this complex did not improve emulsions’ physical stability when it comes to droplet size, it has contributed to maintaining the emulsions’ original color. As for chemical stability, the WP-CMC complex decreased the production of off-flavors resulting from the deterioration of d-limonene and citral under accelerated oxidation conditions.