Tuning the extraction methodology targeting protein-enriched fractions from red algae

•Osborne method can be successfully applied to red macroalgae aiming protein fractioning and characterization.•Red macroalgae proteins showed to be mostly soluble in water and NaOH.•Proteins with different potential functionality were obtained with different extraction solvents sizes.•Different solubilization strategies were adjusted for the different seaweeds. Alternative protein sources are being studied to substitute animal protein production and decrease the environmental issues that are inherent to the production of animal-based foods. This study investigates the potential of red macroalgae (Gracilaria verrucosa, Porphyra dioica, and Palmaria palmata) as an eco-friendly alternative protein source. Using the Osborne fractionation methodology, proteins were extracted under varying parameters (pH and grinding) and techniques (ultrasound and enzymatic extractions). Seaweed proteins exhibited a strong affinity for water and alkaline environments. Optimal extraction yields were obtained with H2O for G. verrucosa (33.24 ± 1.81 g protein/100 g algae protein) and P. palmata (29.56 ± 1.73 gprotein/100 galgae protein), while P. dioica showed highest yields with aqueous 0.1 M NaOH (26.28 ± 5.90 gprotein/100 galgae protein). Molecular weight patterns revealed aggregates (> 200 kDa) in G. verrucosa and P. palmata in the 0.1 M NaOH fraction. H2O extracts displayed peaks (48–84 kDa) linked to phycobiliproteins, showcasing good emulsifying properties. Solubility varied with solvents, with saline and 70 % EtOH dissolving lower molecular weight proteins. Aqueous 0.1 M NaOH extracts demonstrated promising texturizing capacity. Overall, proteins from red macroalgae show potential for food product development, offering an alternative with lower environmental impact compared to conventional animal-based proteins. [Display omitted]