Microfluidic production of monodisperse biopolymer particles with reproducible morphology by kinetic control

Abstract

Microdroplets of phase separating and gelling gelatin-maltodextrin mixtures were produced by a microfluidic technique. The microstructures observed inside the gelled particles were highly reproducible. This resulted from both the controlled production of monodisperse droplets in a microfluidic device and the tuning of gelation and phase separation kinetics.We showed that the internal particle microstructure can be tailored by varying the cooling rate (90 °C/min, 55 °C/min, 5 °C/min), the biopolymer composition (4% gelatin and 6%–7.3% maltodextrin) and the gelatin type (lime hide, pig skin). The particles were analyzed using confocal scanning laser microscopy and image analysis. Microstructures with smaller domain sizes were formed at the fastest cooling rate (90 °C/min), and microstructures with large domain sizes were obtained at the slowest cooling rate (5 °C/min). Furthermore, differences in particle morphology were observed at this slowest cooling rate. In particles containing pig skin gelatin, maltodextrin was located in the core, whereas gelatin was present at the water–oil interface. The opposite was observed for particles consisting of lime hide gelatin where the maltodextrin was found toward the oil phase. The results also showed that a higher concentration of maltodextrin formed larger bicontinuous microstructures compared to the ones obtained with lower concentrations.