Intact oleaginous yeast cells act as active filler in a curdlan gel matrix

Designing a food matrix capable of incorporating cell-based biomass into common food products is still an open challenge. In cell-based food design, cell disruption and biomass drying are key pretreatment steps, which define the structural and functional properties of the biomass. This study explored the addition of wet oleaginous yeast biomass into curdlan hydrogels and how cell integrity influences gel formation and techno-functional properties. Intact and broken yeast were incorporated into curdlan to form cold-set (60 °C) and heat-set (90 °C) gels. Texture, rheology, water holding capacity (WHC), freeze-thaw stability, and microstructure were analyzed to evaluate structure-property relationships. Optimal cell loading was 1% for cold-set gels and 5% for heat-set gels. At these concentrations, intact yeast enhanced hardness, cohesiveness, storage modulus (G′), and linear viscoelastic region (LVR), while reducing frequency dependence, indicating enhanced network stability. Microscopy revealed that intact cells were embedded in the curdlan matrix with filament-like interfacial connections. In contrast, broken yeast cells exhibited partial phase separation and provided weaker reinforcement, although both intact and broken yeast cells improved WHC and freeze-thaw stability. Excessive cell loading disrupted the structural integrity of the gel network, indicating a shift from a reinforcing effect to filler-induced structural heterogeneity. Overall, intact cells behave as active fillers within curdlan gels, whereas broken cells mainly contribute to water retention. These findings highlight the potential of wet microbial biomass as a functional ingredient in food design, enabling more streamlined and sustainable processing strategies.