Coffee crema significantly influences the quality of coffee beverages and is affected by the brewing technique, as the final composition relies on various process parameters. To address this, coffee systems were simplified using model solutions that effectively represented key foaming properties. The study focused on a novel foaming technique aimed at enhancing cold brew coffee foams through a three-step process: 1) dissolving gas into a coffee solution under pressure; 2) gradually releasing pressure to induce bubble nucleation, growth via gas diffusion, and bubble ascent; 3) accumulating bubbles at the surface to form foam. The gases examined were nitrogen and carbon dioxide. Nitrogen's low solubility in aqueous systems hampers nucleation and foaming studies, while carbon dioxide exhibits higher solubility and favorable diffusion properties, significantly reducing interfacial tension, especially above its critical pressure. The results indicated that higher pressures led to more nucleated bubbles and reduced growth during ascent. However, foams generated under these conditions were unstable and collapsed during formation. Additionally, a theoretical evaluation of nucleation and bubble growth through a 3D model highlighted that interfacial tension and liquid supersaturation are crucial parameters influencing these processes.
