Value-added bio-based emulsifiers from dairy waste valorization

Sugar fatty acid esters (SFAEs) are non-ionic surfactants characterized by excellent interfacial tension reduction capability, low toxicity, and biodegradability. These properties make SFAEs extremely promising for their use in cosmetic and food applications. Moreover, this class of surface-active molecules can be obtained from renewable sources, thus answering the need for sustainable and circular chemistry [1]. Herein, cheese whey permeate (CWP), the main waste stream of dairy industry, was used as raw material in the production of bio-based surfactants. Specifically, CWP was enzymatically hydrolysed into a glucose and galactose mixture which was then submitted to a two-step chemoenzymatic synthetic approach [2]. The first step, namely Fischer glycosylation, was not straightforward since several parameters influenced both yield and isomeric ratio. Therefore, a chemometric study was conducted to optimize the reaction conditions. In the second step a solvent-free enzymatic esterification reaction was performed to obtain n-butyl 6-O-palmitoyl-D-glycosides isomeric mixture. The surfactancy of the synthesized bio-based surfactants was deeply evaluated in terms of static/dynamic interfacial tensions. Turbidimetric and confocal microscopy analysis were used to study their water-in-sunflower oil (W/O) emulsion stabilization capacity over time. Finally, computational studies were performed to investigate the role of the ring size on the final emulsifying properties of the isomeric mixture.