Encapsulation of antioxidant compounds in biopolymer micelles

Abstract

This manuscript presents the method for encapsulation of antioxidant agents in micelles of biopolymeric origin. The role of antioxidant agents is played by tannic acid or birch leaf extract, which is a natural source of polyphenolic compounds. The products were obtained in the form of o/w nanoemulsions. The obtained nanoemulsions were characterized by studying their physicochemical and utility properties. The size and electro-kinetic potential of the micelles were measured by dynamic light scattering (DLS). The creaming index and encapsulation efficiency are also provided. The use of statistical tools enabled analysis of the influence of independent parameters on the limits describing the emulsions’ properties. Nanoemulsions with birch leaf extract reached an encapsulation efficiency equal to 80–90%, which remained quite constant over time. It was possible to obtain nanoemulsions with birch extract that were homogeneous over the whole observation period. The values of electro-kinetic potential ranged up to −40 mV, which proves the high stability of these nanoemulsions. More desirable results were achieved in the case of obtaining nanoemulsions with tannic acid. In the beginning, the encapsulation efficiency was very effective (approximately 70%), but after a few days it decreased to values of around 30%. That meant that the tannic acid was released from the micelles with time. After 14 days of observation, the creaming index values were very low, which proves their high homogeneity. These nanoemulsions were stable in time, which was reflected by their electro-kinetic potential values (>20 mV).