Formation of flaxseed gum-based 3D printed bigels: Impact of oleogelator types and oleogel/hydrogel ratios

Bigels possess adjustable texture and rheological property that makes them suitable for 3D printing. This research aimed to develop novel bigels incorporating flaxseed gum (FG) hydrogel with typical oleogels, including rice bran wax (RBW), 12-hydroxyoctadecanoic acid (HSA), and ethyl cellulose (EC) oleogel at different oleogel contents and to evaluate their effects of different oleogels on gelation mechanism and 3D printing performance of bigels. The study systematically elucidated the impact of different oleogelators and oleogel contents on structural and mechanical properties of 3D printed flaxseed gum-based bigels. Bigels transitioned from O/W to bi-continuous with increasing in oleogel content. The storage modulus was proportional to oleogel/hydrogel ratios in all bigels. Mechanical stability of RBW-based bigels and HSA-based bigels was higher than that of EC-based bigels. Thermal stability of bigels decreased as oleogel contents rose. EC-based bigel with 30% oleogel content had the highest enthalpy of melting (1175.46 ± 26.67 J/g). RBW-formulated bigel with 50% oleogel content performed the best 3D printability. The formation of bigels were mainly reflected in two modes: RBW crystals and EC played a synergistic role with FG to maintain the stability of bigel structure, while HSA competed with FG for hydrogen bonds before forming a new balanced network in bigels. This work lays important foundation for developing bigels in future personalized diets.