Synergistic rheology of chia and aloe vera mucilage with Spirulina residue: Enhancing emulsion stability for sustainable food applications

This study was conducted in two phases to develop sustainable, plant-based food emulsions using chia and aloe vera mucilage combined with Spirulina residual biomass (SRB), a protein-rich byproduct from phycocyanin extraction aimed at valorising industrial residues. In the first phase, a response surface methodology was applied to evaluate the rheological properties of aqueous dispersions containing both mucilage and 1 wt% SRB, which constituted the continuous phase of the emulsions. Results revealed a significant synergistic effect between chia and aloe vera : higher chia content enhanced elasticity, while a near 50:50 ratio provided maximum viscosity. While the chia-to- aloe vera ratio had a greater influence on gel-like behaviour, affecting parameters such as elasticity and structure development, the total mucilage concentration had a more pronounced effect on flow properties. Scanning electron microscopy confirmed this synergy by revealing a cohesive and structured network formed through the integration of chia's granular particles and aloe vera 's fibrous elements. In the second phase, these mucilage-SRB dispersions were used as the continuous phase in algal oil emulsions. While SRB alone demonstrated strong emulsifying capacity by producing the smallest initial droplet sizes, it also exhibited the highest creaming rates, indicating limited emulsion stability. The addition of chia and aloe vera mucilage significantly reduced creaming by up to 87 % and limited droplet size growth by up to 11 % after 15 days. These findings highlight the functional role of SRB as an emulsifier and the crucial stabilizing effect of chia and aloe vera mucilage in producing clean-label, stable food emulsions. • Chia and aloe mucilage act synergistically to enhance dispersion viscoelasticity. • Mucilage ratio impacts gel-like behaviour of dispersions more than concentration. • Spirulina biomass alone yields smallest emulsion droplets due to protein content. • Different chia–aloe ratios reduce coalescence and creaming in emulsions. • Microstructure shows synergistic network reinforcing emulsion stability.