Functional Properties of Emulsified Honey–Vegetable Oil Mixtures

Abstract

While the physical and chemical properties of natural honey are well-known, the functional properties of its emulsified mixtures with colloidal particles and vegetable oils are unknown. Herein, we show that natural honey is immiscible with vegetable oils at ambient temperature, making them suitable candidates for emulsification. When emulsified with colloidal particles like precipitated CaCO3 (Socal R1E FG, Calofort U and Calofort SV), the mixtures gave stable vegetable oil-in-honey emulsions. Both Socal R1E FG and Calofort U are unmodified CaCO3 particles, while Calofort SV is modified (coated with 3% stearic acid). The functional properties (namely droplet size and stability to creaming and coalescence) of these emulsions were investigated. The oil droplets in the emulsions were several microns, and after an initial small degree of coalescence, the emulsions remained stable for up to one year without creaming and further coalescence. Emulsions from Socal R1E FG had superior stability in comparison with those from Calofort U and Calofort SV. The apparent contact angles of honey and vegetable oil drops on glass slides coated with the particles are ≥90 and <1°, indicating that the particles are honephobic and oleophilic, respectively. When placed in vegetable oil, the apparent contact angles of a honey drop on the particle-coated glass slides were >90° for all the particles, with the highest values on Calofort SV-coated glass slides. Irrespective of the magnitude of these angles, all the particles formed vegetable oil-in-honey emulsions. This work opens up new opportunities for both the food and pharmaceutical industries. For instance, because honey is naturally sweet, these emulsions can be used in the formulation of novel food products without adding sweeteners. Furthermore, the emulsions can be used as bread, biscuit, or cracker spread, that is, as a substitute for margarine that has an appreciable fat content. In addition, these emulsions can be used for microencapsulation of water-labile food and pharmaceutically active ingredients.