Bigels as potential inks for extrusion-based 3d food printing: Effect of oleogel fraction on physical characterization and printability

Abstract

This study aimed to develop, characterize, and evaluate the three-dimensional (3D) printing performance of new food-grade bigels using different printer parameters (nozzle diameter and printing speed) and material properties (hydrogel (HG)/oleogel (OG) ratio). Two types of bigels were prepared by constant homogenization of beeswax OG with agar and xanthan gum (XG) HG (ABs), and the same OG with gelatin and XG HG (GBs) with different OG concentrations (5, 10, and 20% w/w). Bright-field micrographs confirmed the presence of an OG-in-HG system in all bigel formulations. Scanning electron microscopy images showed that particles in the bigels with a higher OG concentration were better distributed and denser networks were formed. The FTIR results suggested that all bigels were formed from a physical mixture of the OG and HG phases. The rheological analyses of both bigels showed that regardless of the OG concentration, they were more solid than liquid (G′ > G″) and exhibited noticeable shear thinning, which allowed the printing of all bigels. However, the ABs with 10 and 20% OG exhibited better printing performances, with less dimensional variability, excellent surface quality, and good reproducibility. The same results were achieved for GBs with an OG concentration of 20%. The texture profile of the components printed using the ABs and GBs was dependent on the printing parameters, and the GBs presented greater values than the ABs. 3D printing of bigels has not been comprehensively studied. This study expands the development of these systems with potential in 3D food printing and generates insights for possible applications and future studies.