Freeze- or spray-dried gluten hydrolysates. 2.: Effect of emulsification process on droplet size and emulsion stability Original Research Article

Two gluten hydrolysates differing only in the drying process were studied: LS2 was freeze-dried and PS2 was spray-dried. The effect of emulsification procedure (turbo-mixer, valve-homogeniser) was determined as a function of the composition of the aqueous phase (hydrolysate dispersions, soluble fractions). With turbo-mixer, all emulsions presented a monomodal droplet size distribution but emulsions formed with hydrolysate dispersions were unstable whereas these formed with soluble fractions were very stable. With hydrolysate dispersions, the use of a valve-homogeniser decreased droplet size and improved considerably the resistance to coalescence. Nevertheless, the enhancement of emulsion stability was higher with LS2 dispersions than with PS2 dispersions. In contrast, with soluble fractions, emulsions formed with valve-homogeniser remained highly stable but the droplet distribution became polymodal. The higher energy input provided by a valve-homogeniser resulted in the insoluble fraction becoming involved in the emulsion formation. This led to a narrower droplet size distribution and more stable emulsions.