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.