Autolysis-driven cell wall remodeling in yeast: Sustainable bioink development and extrusion 3D printing performance

Brewer's spent yeast (BSY), a brewing byproduct enriched in β-glucans and mannoproteins, is an abundant yet underexploited biomass for sustainable biofabrication. However, the native cell wall structure of BSY limits hydration, and flowability, restricting its direct application in 3D food printing. In this study, we employ autolysis to remodel yeast cell walls and enhance their performance as sustainable bioinks. Autolysis induced pore formation and partial relaxation of the cell wall matrix (SEM/TEM), accompanied by protein depletion and polysaccharide enrichment. Consequently, autolyzed BSY showed a 1.9-fold higher water-holding capacity (356 % vs 189 %), increased surface roughness (2.09 nm vs 1.14 nm), and a less negative zeta potential (-20.47 → -15.13 mV). Rheological profiling revealed a pronounced shear-thinning behavior (flow index 0.64 → 0.12) and a two-order-of-magnitude increase in yield stress (6.10 pa → 1116.25 pa), enabling smooth extrusion and excellent shape fidelity (dimensional accuracy ≈ 99-101 %). These structure-property improvements result from increased accessibility of polysaccharide surfaces and reduced electrostatic repulsion, promoting hydration-driven intercellular interactions and network formation. Collectively, this work establishes autolysis as a scalable valorization pathway that converts industrial yeast residues into functional biomaterials, linking brewing byproducts with sustainable bioink design and emerging 3D food printing technologies.