Formation of natural casein micelle nanocapsule by means of pH changes and ultrasound

Abstract

The effects of alkaline pH and ultrasound treatment on the formation, structure, encapsulation efficiency (EE), and protective properties of natural casein micelles were investigated. With raising the pH, the turbidity of skim milk reduced while the size of casein micelle particles as well as their physical stability and encapsulation capability increased, likely due to the loose-fitting structure of natural casein micelles and the electrostatic repulsion between the casein molecules where all these changes ultimately led to an increase in availability of interior hydrophobic areas. As a result, the hydrophobic compounds can be incorporated in the most interior part of natural casein micelles where with the further pH change they can be encapsulated as nano-particles. Moreover, the EE was 92–97% depending on the measurement technique and oil content. Furthermore, the protective effect of casein micelle nanocapsules against UV showed a considerable difference on oxidative stability. Based on our findings, a novel approach was presented to utilize the natural casein micelles of fresh milk, while maintained their natural structure and functions, for nano-encapsulation and stabilization of the hydrophobic nutraceuticals which can be potentially used for enrichment and fortification of foodstuffs as well as pharmaceutics.