Advancing microalgal applications: Process optimization and functional integration of lyophilized Spirulina biomass in formation of protein-enriched cheddar-type cheese

•Spirulina proteins offer a sustainable alternative to animal rennet as a vegetarian functional ingredient in cheese production.•Incorporating Spirulina biomass in cheddar-type cheese enhances protein content (up to 39.21 %) and antioxidant potential (20.69 % to 37.66 %).•Optimized production using RSM results in improved cheese yield (up to 6.01 %) and standardized processes.•Spirulina-derived cheese exhibits better protein retention, reduced fat content, and health benefits due to its bioactive compounds Spirulina is a well-known food supplement renowned for its high protein content, bioactive compounds, and enzymes that are pivotal in its metabolic processes. This study explores the potential of Spirulina as a sustainable alternative to animal rennet, proposing it as a vegetarian functional ingredient in cheddar-type cheese production. The research utilized response surface methodology (RSM) to optimize the incorporation of lyophilized Spirulina biomass, focusing on maximizing protein content and antioxidant potential. The optimized process resulted in cheese yields ranging from 1.96 % to 6.01 % and protein contents between 14.29 % and 39.21 %. We identified and standardized conditions for achieving these optimal outcomes. Analysis of milk clotting activity (MCA) and proteolytic activity (PA) showed pH and temperature-dependent variations, with traditional rennet and acetic acid cheeses demonstrating superior MCA. In contrast, Spirulina-enriched cheeses exhibited enhanced antioxidant activity (20.69 % to 37.66 %), improved protein retention, and lower fat content, attributed to its inherent bioactive compounds. Fourier-transform infrared (FTIR) and Raman spectroscopy provided insights into the molecular composition and structural changes during storage, highlighting the distinctive properties of Spirulina-derived cheese. This study underscores the viability of integrating Spirulina biomass into cheese production, offering a pathway to create nutritious, antioxidant-rich products with elevated protein content and functional benefits. [Display omitted]