Development of beetroot powder-enriched inks for 3D food printing based on hydrogel/oleogel bigels

Abstract

3D printing with bigel inks exhibits substantial potential for food structuring and nutritional innovation, particularly through the enrichment of foods with vegetables rich in health-promoting bioactive compounds. This study focuses on the preparation of bigels incorporating beetroot powder. Hydrogels based on xanthan gum, carrageenan, and guar gum were used in combination with monoglyceride oleogels to formulate suitable inks for extrusion-based 3D food printing. This study investigated the effects of hydrogel type, vegetable powder content, and hydrogel:oleogel mass ratio on the microstructure, rheological properties, and extrusion behavior of the bigels. Furthermore, the printability of the selected formulations was evaluated. The inclusion of beetroot powder enhanced the structure and mechanical strength of all the hydrogels. Bigels prepared with an 80:20 mass ratio yielded homogeneous materials for all three hydrogelators. They exhibited maximum storage modulus values of 1.1E4, 7.8E3, and 3.3E3 Pa for guar gum, carrageenan, and xanthan gum, respectively. Moreover, these bigels partially recovered of their initial structure after the application of high strain and demonstrated appropriate flowability for extrusion through 1.2 and 2 mm 3D printer nozzles. Successful printing of 2D (grid) and 3D (cube) structures was achieved using guar gum-based bigels, followed by carrageenan-based counterparts, which displayed superior dimensional accuracy, structural integrity, enhanced line resolution, and minimal printing errors and deformations. These findings provide valuable insights and lay the groundwork for developing more complex and functional food structures.