Effect of in Vitro Gastrointestinal Environment on Astxanthin-Loaded Pickering High Internal Phase Emulsions Stabilized by Silkworm Pupa Protein

Abstract

In this study, the stability of Pickering high internal phase emulsions (HIPEs) stabilized by silkworm pupa protein in an in vitro gastrointestinal environment and their astaxanthin loading capacity as well as the bioaccessibility of astaxanthin-loaded HIPEs were characterized, and the mechanism of the targeted and controlled release of astaxanthin-loaded HIPEs in the simulated gastrointestinal environment was elucidated by measuring the particle size distribution and zeta potential as well as using confocal laser scanning microscopy (CLSM), reversed-phase high performance liquid chromatography (RP-HPLC) and electrophoresis. The results showed that silkworm pupa protein stabilize effectively stabilized Pickering HIPEs with an internal phase as 78%, and the encapsulation efficiency of AST in the HIPEs was nearly 88%. The Pickering HIPEs remained stable in the simulated gastric environment for 90 min and became progressively unstable with prolonged digestion in the simulated intestinal environment, significantly increasing the bioaceessibility of astaxanthin. The interfacial protein composition of the emulsion indicated that silkworm pupa protein, with a molecular mass of 70 kDa, was the major protein stabilizing the Pickering HIPEs, and its hydrolysis by the intestinal digestive enzymes was the major cause of the destabilization of the emulsion and the release of astaxanthin. The present study provides a theoretical basis for the application of Pickering HIPEs stabilized by silkworm pupa protein for targeted intestinal delivery of hydrophobic bioactive substances, and opens up new possibilities for the application of astaxanthin in the food and nutraceutical fields.

Keywords

• silkworm pupa protein; pickering high internal phase emulsions; astaxanthin; in vitro gastrointestinal environment; stability