Complex structured meat analogues via hybrid extrusion printing by incorporation of oil-containing ionically gelling alginate binders

Over recent decades, consumer demand has driven meat analogue development. While alternatives to minced meat products (e.g. patties and sausages) are widely available, replication of whole-cut meat products remains challenging due to their complex structure and composition including muscle fiber bundles as well as fat-rich connective tissue, which largely determine appearance, flavor, and texture. In this study, the applicability of novel a bi-stream breaker plate system in high-moisture twin-screw extrusion was investigated for the production of structurally complex, multi-phase meat analogues. An inline external gelation approach was employed using CaCl 2 -containing protein-mass to solidify alginate-based binders. Protein-mass temperature (100, 120, 140 °C), binder flow fraction relative to the extrudate (0, 4, 7, 13 wt.%), and dispersed oil content in the binder (0, 10, 20 wt.%) were varied independently. Samples were optically assessed (tearing analysis, Cryo-SEM, CLSM) and mechanical testing (texture profile analysis, cutting tests). Additionally, the rheological behavior of the protein-mass was characterized in dependence of temperature and CaCl 2 concentration. Results show predominantly homogeneous binder distributions up to protein-mass temperatures of 120 °C. Increasing binder fraction did not affect its distribution across the extrudate width. Mechanical analysis revealed a continuous decrease in chewiness (up to 48% reduction), while anisotropy increased by 40% upon initial binder incorporation. Increasing the dispersed oil fraction reduced chewiness (up to 17% reduction). Microstructural analysis confirmed that binder layers spatially separated protein strands, thereby inhibiting their recombination. This scalable extrusion-based process thus represents a promising alternative to 3D-printing, combining protein-rich and oil-rich layers into complex structures.