How much protein kinds influence the morphology of the resulting powder ?
Résumé
Spray drying is a well-established technique to convert a liquid solution into individual and solid particles which is widely used in food industry especially in the dairy sector. This process allows formation of a large range of particle morphology all distinct from each other by their physical characteristics providing to particles a typical aerodynamic behaviour and determining their final functionality. In this study we focused on the drying behaviour of two major milk protein concentrates: whey protein isolate and native micellar caseins. To acquire a better understanding on the role of each protein in the particle forming mechanisms, seven mixtures containing different ratios of caseins and whey proteins were investigated. A micro-fluidic-jet-spray-dryer (MFJSD) was used to produce uniform particles by drying monodisperse droplets in a hot and dry air flow. Powders were characterized with regard to their physical characteristics and their rehydration properties. Besides, characterisation of particle size and shape was ensured by means a dynamic image analysis system. It is shown that particle morphology is mainly governed by the protein material type, almost regardless of the drying kinetics; controlling the product formulation thus represents a potential means to tune particle morphology, and therefore powder functional properties.