Rapeseed oil as the extraction solvent motivates fucoxanthin-loaded high internal phase emulsion preparation for food 3D printing

Fucoxanthin (FX), a non-provitamin A carotenoid pigment, is a well-known natural antioxidant contained in brown algae. The present study deals with an ultrasonic-assisted FX extraction process from Undaria pinnatifida with rapeseed oil as the solvent. Then, high internal phase emulsions (HIPEs) with the FX-rich rapeseed oil as the oil phase was constructed using a simple one-step method for food 3D printing. The FX-loaded HIPEs were stabilized by the gelatin (GE)-based microgel, which were prepared by GE complex coacervation with sodium alginate and transglutaminase cross-linking, for the improved delivery and stability of FX. FX-loaded HIPEs stabilized by 2 wt (wt)% GE-based microgel showed a small and uniform particle size and a stable microstructure. The HIPEs stabilized by 2 wt% GE-based microgel had the best FX stability (residual FX 84.81 ± 0.82%) and bioaccessibility (38.26 ± 1.21%). The excellent viscoelasticity, recovery rate and thixotropy of the HIPEs stabilized by 2 wt% GE-based microgel further confirmed the best 3D printing performance. Therefore, rapeseed oil as the extraction solvent motivates FX-loaded HIPEs preparation, and GE-based microgel concentration is crucial for 3D printing.