Digestibility and enteric release achieved with microencapsulates made from emulsion-templated plant proteins†

Abstract

Microencapsulation of functional ingredients in food and drinks can improve their stability through manufacture, shelf-life, and digestion. A key challenge is to discover materials and approaches that allow cargo to be protected under gastric digestion conditions, yet provide subsequently effective release in the intestine where many actives are most effectively absorbed. Here, we address this challenge by developing a robust plant protein microcapsule with ability to retain oil-based cargo during simulated digestive conditions. To generate the capsule, pea protein isolate was exposed to aqueous organic acid and high shear to form a stable colloidal dispersion. The aqueous dispersion was subsequently emulsified with a test cargo (vitamin D2) dissolved in a solid lipid phase and spray dried to produce microcapsules with a D₅₀ of 19 μm. This process yielded microcapsules with smooth, continuous surfaces and effective internal encapsulation. The stability of microcapsules and release of vitamin D2 cargo was characterised by a static in vitro digestion model following the INFOGEST protocol. The results show that the processing conditions of the pea protein did not negatively impact digestibility. Crucially, our results further show that microcapsules are resilient to gastric conditions but highly susceptible to intestinal conditions, supporting an enteric release profile for vitamin D2 cargo. This study provides a model for encapsulation of oil-soluble cargoes and inspires the development of other encapsulates that would benefit from protective and controlled release mechanisms in food and beverage matrices.