Emilse Negro, Cecilia Dauber, Carla Bonifacino, Cecilia Abirached, Luciana Vera Candioti, C. A. Bernal, Ignacio Vieitez
ABSTRACT Flaxseed cake, a by‐product of oil extraction by cold pressing, has attracted considerable interest due to its nutritional, functional, and medicinal value. It is characterized by its content of proteins, residual oil, dietary fiber, and phenolic compounds. This study aimed to apply sequential supercritical fluid extraction (SFE) for oil removal and pressurized liquid extraction (PLE) for phenolic recovery, while also evaluating the antioxidant activity of the obtained extract and the functional properties of the PLE residue as a potential food ingredient. The flaxseed cake was defatted using SFE at 400 bar and 70°C. Under these conditions, 21.2% ± 0.8% (w/w) of flaxseed oil was recovered, containing 406 ± 9 mg/kg of γ‐tocopherol. PLE, using 100% ethanol, showed a higher concentration of total phenolic compounds (15.0 ± 1.8 mg GAE/g) and a higher ABTS antioxidant capacity (227.3 ± 1.6 μmol TE/g). The addition of the phenolic compounds extract enhanced the oxidative stability of flaxseed oil samples, increasing the induction period to 96%. The functional properties of the PLE residue indicated a maximum protein solubility (40%) under alkaline conditions. This residue, rich in protein and mucilage, exhibited good water retention and oil binding capacities. Emulsion stability was significantly influenced by both protein concentration and pH. The most stable emulsions after 24 h were obtained with a protein concentration of 2.5% and a pH of 4.2. These findings demonstrate that the sequential extraction process was effective in recovering residual oil and phenolic compounds. This approach highlights the importance of implementing environmentally friendly extraction methods that not only minimize ecological impact but also promote the valorization of agroindustrial by‐products.