Development of soy glycinin-gum arabic complex coacervates: Fabrication of colon-targeted microcapsules and their effect on gut microbiota.

It is challenging to fabricate oil microcapsules based on plant protein-polysaccharide complex coacervation. This study first systematically characterized the interaction between soy glycinin and gum arabic. It showed that increasing gum arabic/soy glycinin ratio contributed to the formation of hollow coacervates while shifting pH towards the zero charge point facilitated the formation of solid coacervates. Decreasing pH below zero charge point contributed to the formation of microcapsules with well defined core-shell structure. The structure was further fixed by tannic acid crosslinking in the presence of dextran which acted as structure stabilizer. By carefully controlling the crosslinking procedure, the microcapsules could keep its structure during in vitro gastrointestinal digestion but dissociated upon colon fermentation along with release of free fatty acid. In vivo study confirmed that the oil microcapsules reached the large intestine and reshaped gut microbiota composition.