Whole Gracilaria biomass as a green emulsifier for pickering emulsions: Applications in astaxanthin delivery and fat replacement

Whole Gracilaria biomass (WGB) was developed as a multifunctional emulsifier to overcome key limitations that hinder the sustainable utilization of astaxanthin delivery systems and structured fat replacements. A key novelty lies in its direct utilization of unmodified algal biomass as an emulsifier to stabilize oil-in-water (O/W) Pickering emulsions (PEs) through a unique anionic hydrophilic network. The emulsifier exhibited a zeta potential of-33.5 mV and aqueous contact angle 72.6 degrees. Rheological analysis revealed an unprecedented interdependent viscosity modulation governed by the WGB concentration (5-15 wt%) and O/W ratio (50-80 %), that formed robust viscoelastic networks to inhibit droplet aggregation. This innovative stabilization improved the protection of the encapsulated astaxanthin, with 17.27 +/- 1.3 % and 28.10 +/- 3.65 % of its bioactivity retained at 80 degrees C and photolytic stress for 15 days, respectively, outperforming many traditional delivery platforms in terms of functionality. In emulsified sausages, WGB-PEs delivered a novel dual functionality: they boosted water-holding capacity by 27 % compared to the control (a key attribute for sausage juiciness) and replicated animal fat textures through unique interfacial fibrillar anchoring. This work established fresh algae as a groundbreaking sustainable dual-function ingredient, innovatively resolving emulsion destabilization in bioactive delivery while enabling lipid reduction in processed meats, filling critical gaps in sustainable ingredient technology.