Imaging of Double Emulsions

Abstract

Double emulsions are dispersed liquid systems which provide a variety of applications for example in fat reduction and encapsulation of active agents. Both double emulsion types, water in oil in water (WOW) and oil in water in oil (OWO), are relevant for foods. From the point of view of characterisation, they challenge the measuring techniques classically known and established for dispersed systems. Alternative techniques as diverse imaging technologies and the corresponding data processing strategies are increasingly important in emulsion science. X-rays, electronic beams and nuclear magnetic resonance are major imaging tools which differ in terms of energy scales as well as beam length and time scales that further have an impact on the structural information. Imaging techniques provide a manifold of possibilities but also need an in-depth and thorough data treatment and interpretation. This chapter gives an overview of imaging techniques and data processing currently applied on double emulsions. The focus is, however, not on the technical details but rather on the question of information which can be obtained from the corresponding techniques. Possibilities and limits are discussed based on the physical principles and known applications. Currently applied data analysis strategies are presented, which leads in the last section to the discussion about the information which can be extracted from the data regarding structure, chemical composition and time-dependent processes in double emulsions.