Manufacture of food grade κ-carrageenan microspheres

Abstract The objective of this study was to optimise a method for the manufacture of food-grade κ-carrageenan based microgels with a broad range of functionalities such as nutraceutical delivery systems or fat replacers. In order to obtain small and spherical microgels which would not adversely affect the overall mouthfeel or sensory properties of a food product, a special procedure was optimised based on the emulsification of the κ-carrageenan solution in hot rapeseed oil using a high shear rotor–stator mixer, without the aid of surfactants, followed by fast tempering of the emulsion under mild agitation. The influence of emulsion mixing speed, phase volume ratio, oil and aqueous phase viscosity as well as emulsion temperature, on the particle size and size distribution of the spherical microgels was examined. Results show that best operating conditions for a 4% κ-carrageenan solution are a temperature of 68 °C, a phase volume ratio of 5% and a mixing speed above 3000 rpm. Under these optimised conditions, food grade spherical κ-carrageenan microgels were obtained with a Sauter mean diameter (D[3,2] μm) of 25 μm.