Yeast-Based Pickering Emulsions: Is Yeast Truly the Stabilizing Agent?

The increasing demand for sustainable and affordable surfactants requires the exploration of novel bio-based alternatives. In this context, this work investigates the potential of baker’s yeast (Saccharomyces cerevisiae) as a surface-active agent. To this purpose, the performance of commercial dry, commercial fresh, and cultivated yeast was evaluated by characterizing their wetting behavior and formulating emulsions with a fixed oil-to-water ratio. Microscopic and macroscopic stability was monitored over 24 h and quantified via the creaming index (CI). The experimental results demonstrate that both the yeast source and concentration significantly dictate the surface properties and emulsion stability. Notably, commercial dry yeast exhibited the highest degree of hydrophobicity, likely attributed to the presence of sorbitan monostearate (SMS) in the formulation. Consequently, this was the main variant capable of producing stable emulsions, with microscopic evidence suggesting a Pickering-like stabilization mechanism driven by the irreversible adsorption of yeast cells at the oil–water interface. Conversely, commercial fresh and cultivated yeast failed to exert significant stabilizing activity. These results demonstrate that S. cerevisiae biomass can be effectively repurposed as a functional constituent in green emulsion technology, offering a scalable pathway for the development of biocompatible, particle-stabilized industrial formulations.