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.

DFT Studies of the Activity and Reactivity of Limonene in Comparison with Selected Monoterpenes

“…Additionally, the energy values of the highest occupied molecular orbital show that E HOMO limonene is "in the middle" of the tested monoterpenes and allow for the ranking of the examined compounds from the most reactive ones, respectively: thymol, pienene, limonene, cymene, and menthol. These calculations are partially confirmed by experimental data [14,32]. The use of the solvent model does not significantly affect the structures of the analyzed monoterpenes.…”

“…It is known that limonene undergoes oxidation and degradation in an acidic environment. In order to limit this process, various stabilizers such as whey protein and an electrostatic whey protein-carboxymethyl cellulose complex were used [14]. Nevertheless, a change in the research environment and tests of toilet waters containing limonene showed its high stability [12].…”

“…Similarly, the review monograph on biomass management focusses, among others, on the use of both limonene and pinene [64]. In the literature review presented above, in addition to limonene, pinene [14], cymene [9,10], and thymol [9] were mentioned. These natural compounds, similar to limonene, are obtained from plants [65][66][67] and are monoterpenes known for their unique aromatic, therapeutic properties [65,[67][68][69].…”

Physicochemical Properties and Stability of Emulsions Containing Carotenoid-Rich Pumpkin Extract, Whey Protein Concentrate and Carboxymethylcellulose

“…One factor contributing to their stability is the presence of a polysaccharideprotein complex in the system, which imparts favorable interfacial properties and further aids in stabilization. In line with this, Kaade et al (2022) demonstrated that the chemical stability of D-limonene-containing emulsions can be improved by employing a complex of whey protein and Carboxymethyl Cellulose (CMC). However, the effect of this complex on the physicochemical properties and stability of carotenoid-containing emulsions remains unknown.…”