Laboratory Experiment on Emulsions: Study of the Effect of Osmotic Pressure on Double Emulsions Preparation

Double emulsions are ternary systems commonly used in several disciplines in areas such as food technology, applied chemistry, chemical engineering, materials science, pharmacology and environmental science. In several courses related to these areas, the implementation of laboratory experiment is required to strengthen the knowledge acquired by students during the theoretical lessons. However, it is difficult to find published practical experiments in this field. This work presents a four-hour hands-on laboratory experiment in which students can easily formulate and prepare water-in-oil-in-water double emulsions for vitamin B12 encapsulation. In this experiment, students can analyze the effect of the osmotic pressure produced by the addition of different NaCl concentrations in each aqueous phase, which could lead to the swelling and deswelling phenomena of the inner aqueous droplets and, therefore, affect the encapsulation efficiency of the formulated systems. The double emulsions are analyzed by the students in terms of size and encapsulation efficiency.