Batch versus microfluidic emulsification processes to produce whey protein microgel beads from thermal or acidic gelation

Abstract: Producing food-grade soft particles with controlled structure is of interest to elucidate the structure-properties relationship in soft-particles suspensions. The aim of this work is to evaluate the ability of two elaboration processes to produce homogenous and spherical whey protein microgels with adjustable diameters in the range 40-100 $\mu$m. Microgels are formed in two steps: (1) emulsification of a whey protein aqueous solution in oil and (2) gelation of the protein solution droplets. We compare a continuous emulsification in a home-made microfluidic device, designed on purpose, with a more simple emulsification by mixing. In addition, two gelation processes are studied: a thermal gelation at 80{\textdegree}C and an acid gelation. Results sshow that emulsification controls the size polydispersity (pdI<0.1 for microfluidics) while gelation controls the microgels structure and assembly. Acid gelation in the microfluidic device results in spherical, homogeneous microgels which properties are controlled by the process parameters.