Spatial distribution of lipids modulated by phase separation in emulsified films and the effects on structure-function relationships

The aim of this work was to develop a novel strategy to modulate the spatial distribution of paraffin in emulsified films via tuning phase separation behaviors among zein/gelatin (ZG) matrix, and to elucidate their structure-function relationships. Three phase separation behaviors within ZG matrix, namely, the zein-dominated, gelatin-dominated and ZG-macro phase separation, were developed. When the ZG matrix was tuned to ZG-macro or gelatin-dominated phase separation, the successive or partial bilayer films can be developed due to the spatial distribution of paraffin as the floating layer. While, when zein-dominated phase separation was created, paraffin uniformly distributed as dispersed phase, forming films with monolayer structure. Surface distribution of paraffin, detected by AFM, revealed that distinct interactions between paraffin and zein or gelatin drove the distribution pattern. The bilayer structure more effectively enhanced water barrier properties of films and performed preferable mechanical properties but at the expense of optical properties, whereas the release property of oregano essential oil and tea polyphenol was dominated by the chemistry nature of film matrixes rather than the spatial distribution. This study adds new knowledges to the rational design of emulsified films by tuning the spatial distribution of lipids.