κ-Carrageenan-sodium caseinate microgel production by atomization: Critical analysis of the experimental procedure

The influence of atomization process to produce κ-carrageenan and κ-carrageenan/sodium caseinate microgels was studied experimentally (aspect ratio and particle size distribution) and theoretically (dimensionless parameters). Moreover, rheological behavior of microgel suspensions was evaluated to examine their potential application in food products. Experimental results demonstrated that the size of microgels was influenced by feed flow rate, compressed air flow rate and composition of solutions, while their shape depended on the viscosity and surface tension of biopolymer solutions. Regarding the dimensionless numbers, higher values of Reynolds number of liquid layer (Reλl) and Weber number (Wel) led to smaller particles, while the decrease of Ohnesorge number (Oh) was related to lower sphericity of microgels. Rheological behavior of suspensions depended on not only the morphology and size of microgels, but also their composition. Incompatibility between κ-carrageenan and sodium caseinate in mixed microgels led to suspensions with more complex rheological behavior at determined biopolymer concentrations.