Amorphization and microencapsulation of β-carotene with improved physical stability and bioaccessibility for emulsion-based 3D printing.

BACKGROUND: β-Carotene is widely used as a natural colorant and nutritional ingredient, but its poor water dispersibility, high crystallinity and low stability limit its application in functional foods and three-dimensional (3D)-printed food systems. In this study, a solvent-free hot-melt/quenching strategy was combined with wet milling and spray drying to fabricate amorphous β-carotene microcapsules using octenyl succinic anhydride-modified starch (OSA-starch) and trehalose as wall materials. RESULTS: Hot-melt/quenching treatment effectively transformed crystalline β-carotene into an amorphous state, and the optimal condition was determined as 220 °C for 22 s followed by liquid nitrogen quenching. Compared with crystalline β-carotene microcapsules, amorphous β-carotene microcapsules showed reduced crystallinity and improved encapsulation behavior. The incorporation of trehalose into the OSA-starch wall matrix further decreased particle aggregation, improved redispersibility and enhanced storage stability. After 40 days of storage, amorphous β-carotene microcapsules prepared with the OSA-starch/trehalose composite wall materials (AB-Tre) retained 82.2% and 58.9% of β-carotene at 25 °C and 55 °C, respectively, which were higher than those of the other formulations. During in vitro digestion, AB-Tre showed better colloidal stability and higher β-carotene bioaccessibility than crystalline β-carotene microcapsules prepared with the OSA-starch/trehalose composite wall materials (CB-Tre). Furthermore, AB-Tre-loaded high internal phase emulsions showed good printability and could be used to fabricate customized 3D structures. CONCLUSION: The combination of hot-melt-induced amorphization and OSA-starch/trehalose microencapsulation provides an effective strategy to improve the stability, bioaccessibility and 3D printing applicability of β-carotene. © 2026 Society of Chemical Industry.