Dissociation of self-assembled casein nanoparticles by ascending the pH and sonication

Casein self-assembled nanoparticles were formed by dispersing casein sodium salt either in deionized water or phosphate buffer containing CaCI ₂. The pH of casein solutions was adjusted on different values in the range 7.0-9.9 followed by sonication for 5 minutes. Presence of calcium phosphate in aqueous solution caused a decrease in the light transmittance capability, resulting in a higher turbidity. This suggested the presence of denser and larger structures which was approved by the increased proportion of protein in the colloidal phase upon centrifugation compared with that of solutions made with deionized water. Light transmittance of casein solutions increased as pH increased. At pH values ≥ 8.6 the protein content of centrifugal supernatants from solutions made in phosphate buffer containing CaCI ₂ increased with the increasing pH. Sonication increased the light transmittance of casein solutions and total protein content in supernatant. The higher the pH, the higher was the influence of ultrasound.