Effect of pH on Garlic Oil Encapsulation by Complex Coacervation

Coacervation is known to be true microencapsulation because the core material is completely surrounded by a continuous coating of wall material. Coacervation involves interaction between one or many hydrocolloids, particularly between oppositely charged protein and polysaccharide in the same reaction media [1]. The interaction relies on the charges carried by the biopolymers, pH of the coacervation mixture, ionic strength, ratio between the two biopolymers, accessibility of the charges for interaction and other mechanical and physical factors. pH plays an important role in complex coacervation because it affects the formation of protein-carbohydrate complexes by influencing the degree of ionization of the functional group of protein (amino group) and carbohydrate (carboxyl group) [2]. In a mixture containing an anionic polysaccharide and a protein, adjustment of pH below the isoelectric point (pI) or the electrical equivalence pH (IEP) would result in maximum electrostatic attraction as the two biopolymers are carrying oppositely charge. Polymer systems that have been reported for microencapsulation via complex coacervation include gelatin-gum acacia [3-5], whey protein-gum acacia [6] and soybean protein isolategum acacia [7].