How does the water contact angle control gas marbles formation with different edible particles?

Three-phase water contact angle is a key parameter in the stabilization of particle-stabilized foams and emulsions. Gas marbles, which are particle-stabilized bubbles suspended in gas phase, are expected to be similarly influenced by the three-phase water contact angle. We hypothesize that the ability of particles to form gas marbles is strongly dependent on this parameter.

We investigated the ability of various edible particles with different sizes, shapes, and compositions to form gas marbles. For each particle, we examined gas marble formation, measured the three-phase water contact angle, and assessed the structure and stability of the resulting gas marbles.

Our results show that gas marble formation is critically dependent on the three-phase water contact angle on particles. Three distinct groups emerged: (1) Hydrophobic particles (high contact angle): No gas marble formation occurred, the air bubbles burst in the contact of the particles layer; (2) Highly hydrophilic particles (low contact angle) also failed to form gas marbles, as their strong affinity to water prevented stabilization at the air/water surface; (3) Moderately hydrophilic particles (intermediate contact angle) leading to successful gas marble formation. Our results indicate that an optimal range of three-phase water contact angle is essential for gas marbles formation whatever the particles size and shape. This study, for the first time, highlights the critical role of this parameter in the stabilization of gas marbles. The resulting gas marbles showed remarkable stability, including resistance to drying and heating and also mechanical resistance, highlighting their potential applications in edible materials.