A new strategy for the preparation of long-term stable “Capillary foam” from egg white protein microgel particles

Abstract

Foam stabilization plays a pivotal role in the shape retention and taste enhancement of foam-based foods. Micron-sized egg white protein microgel particles (EWPM) were prepared by heat-treating natural egg white protein. EWPM solution incorporating minimal amounts of coconut oil (CO) combined with high-speed shearing produced synergistically stabilized “capillary foam”, offering a novel approach to foam stability challenges. A comparison of the “capillary foam” with Pickering foam stabilized solely by EWPM revealed superior long-term stability, with the former maintaining structural integrity for up to 60 days. Stable “capillary foam” was achieved when particle sizes were in the micron range (3–4 μm). Long-term foam stability was observed even when the contact angle of particles at the oil/water interface exceeded 120°, as particles and the oil phase jointly stabilized the foam system. Confocal laser scanning microscopy revealed the adsorption of oil and particles together on the surface of bubbles within the “capillary foam” system. The formation of a gel network structure by the oil phase and particles resulted in bubble immobilization, reduced mobility, and slowed attenuation. The dispersion of the oil phase around the bubbles was facilitated by the particles, enhancing the stability of the oil/water and oil/air interfaces compared to the air/water interfaces in classical Pickering foam. The EWPM/CO system showed notable advantages over a single EWPM in creating edible foams with enhanced stability and oil resistance. This study successfully developed food-grade particles capable of stabilizing “capillary foam” and established an innovative approach to the utilization of egg white protein in foam-based foods, with considerable potential for applications in flavor foams and nutritional foams.