Carotenoid bioaccessibility in food-grade Bigels: Impact of hydrogel:Oleogel ratio and 3D printing

In this study, food-grade bigels were developed as carriers of natural carotenoids and tailored for 3D printing applications. Bigels were prepared with agar-based hydrogels and carnauba wax-based oleogels at different hydrogel:oleogel (H:O) ratios (80,20, 60,40, 40,60, 20,80). Carotenoid-rich extracts from Arthrospira platensis and Scenedesmus obliquus were selected due to distinct profiles of carotenes and xanthophylls. The effects of H:O ratio and 3D printing on carotenoid digestive stability, micellization, and bioaccessibility were evaluated using an in vitro digestion model. Both H:O ratio and 3D printing significantly influenced carotenoid bioaccessibility, with responses strongly dependent on carotenoid composition and concentration. In A. platensis , micellar fractions contained both carotenes and xanthophylls, while S. obliquus extracts were dominated by xanthophylls (>90%). Within these complex extracts, xanthophyll-rich systems exhibited higher digestive stability, micellization efficiency, and bioaccessibility compared to carotene-rich systems. 3D printing modulated carotenoid digestive stability and micellization in a manner dependent on extract type and H:O ratio, resulting in a significant increase in final bioaccessibility of up to 12%, particularly in 80:20 bigels. Overall, bigels combined with 3D printing demonstrated strong potential as delivery systems for natural carotenoid extracts. • Bigel systems enhanced the bioaccessibility of natural, complex carotenoid extracts. • Bigels increased carotenoid bioaccessibility compared to oleogels (up to 40%). • Hydrogel:oleogel ratio modulated carotenoid micellization and bioaccessibility. • Extract composition influenced carotenoid response to bigel microstructure. • 3D printing altered bigel microstructure and impacted carotenoid digestion.