Effect of oleogelators on rheological tunability and 3D printability of xanthan gum-κ-carrageenan based bigel inks

This work applied 5% to 25% (w/v) beeswax as oleogelator to prepare bigel ink and investigated the relationship between printing precision and rheological properties. As oleogelator content between 5% to 10%, the line width deviation reached 130.52% and 36.72% while the printing precision of bigel inks decreased to 62.98% and 85.73%. Increasing the oleogelator content to 15%, the line width deviation significantly decreased to 5.68%, and the printing precision reached 97.63%. As oleogelator content exceeded 20%, the printing precision of bigel ink was higher than 99% and was capable of printing the outward-flapping rabbit model with 12.50 mm height and 21.50 mm length. Rheology demonstrated that as the oleogelator content reached 25%, the flowing index (n_H) and critical strain of the bigels decreased to 0.18 and 0.095%, indicating improved extrudability. In contrast, the consistency (K_H) and gel strength (A value) increased to 25.08 × 10² Pa·sⁿ and 29.26 × 10⁶ Pa s^1/z, along with higher recovery viscosity and yield stress, indicating improved self-supporting ability. These might be attributed to a stable microstructure. Bigel inks with higher oleogelator addition could withstand high shearing without hydrogel particle aggregation. Moreover, β' and β crystal structures formed by beeswax could offer sufficient mechanical strength and stronger texture profiles. The weak connection between crystals allowed bigel inks to recover quickly after extrusion, while a denser crystal cluster restricted moisture movement. Future work should clarify specific application scenarios of bigel in food manufacturing and the deeper mechanism of crystal influence for 3D printing precision.