Editorial: Liquid foams and emulsions stabilized by bio-based particles

Abstract

Foams and emulsions are ubiquitous colloidal systems in daily life and technology. From a physico-chemical perspective, these appear as biphasic dispersions formed by the dispersion of a fluid (liquid or gas) as small droplets and bubbles in a continuous liquid medium. The result is the formation of thermodynamically metastable systems that over time tend to separate into their individual components (gas-liquid and liquid-liquid). Amphiphilic molecules are traditionally used to stabilize these systems and try to prevent or delay the destabilization mechanisms. Another type of stabilizer which can be used to stabilize foams and emulsions are partially hydrophobic colloidal particles. These particles are able to adsorb strongly at fluid-fluid (gas–liquid or liquid–liquid) interfaces to sterically hinder coarsening (ripening) and coalescence, as well as to slow down drainage (creaming) by changing the rheological properties of the continuous phase. These foam or emulsion systems are commonly referred as “Pickering” foam/emulsion. The seminal studies in this type of “Pickering-Ramsden” systems were focused on the exploitation of inorganic particles to provide stability to emulsions and foams. However, this type of particles present a limited relevance for practical applications due to toxicity, lack of biocompatibility and biodegradability. In the last decade, there has been a shift toward the development of foams and emulsions stabilized by bio-based particles. The goal of this Research Topic is to show the recent advances in the field of emulsion and foam stabilized by bio-based particles made of proteins (plant proteins and animal proteins). The focus of these articles is on the potential of existing or new protein particle systems as foam or emulsion stabilizers. One of the contributions to these topic is a review article summarizing the recent findings and the open questions remaining about the interfacial properties of protein particles adsorbed at fluid/fluid interfaces, and the links between these interfacial properties and the stability of foams and emulsions (Fameau et al.). There are two research articles focusing on the design and fabrication of protein particles/aggregates. Fameau et al. studied the production and the role of protein aggregates from β-casein on foam stability with temperature by using a multiscale approach. The presence of aggregates increases the foam stability, but they demonstrate OPEN ACCESS