Defatting coconut protein: Influence of solvent polarity and emerging technologies on structural and colloidal properties

Defatting is a crucial pretreatment step in extracting plant proteins from food industry by-products. This study investigated the effects of several defatting methods (EtOH (ET), hexane (HX), supercritical fluid CO₂ (SCO 2 ), and high intensity ultrasound (HIUS) combined with EtOH) on the recovery, structure, functional and colloidal properties of coconut albumin and globulin. The total protein extraction recovery increased from 36.4 % in the non-defatted group (ND) to up to 39.2 % ( p < 0.05) after defatting, mainly driven by the higher globulin recovery (24.9 % in ND to 28.4 % with HIUS, p < 0.05), whereas albumin recovery remained statistically unchanged (11.0 % – 11.9 %, p > 0.05) and was slightly reduced under HIUS (10.8 %, p < 0.05). Defatting had minor effects on secondary and tertiary structures but markedly enhanced protein surface hydrophobicity. Globulin showed increased exposure of hydrophobic groups (204 arbitrary units (a.u.) in ND versus 222–274 a.u. in treated groups, p < 0.05). In albumin, HIUS further amplified this effect compared with EtOH (58 versus 66 a.u., p < 0.05), improving emulsifying capacity. Solvent polarity was directly correlated with protein colloidal and functional properties (|R| > 0.7). Defatting reduced globulin solubility (90 % in ND versus 76–90 % in treated groups, p < 0.05), due to increased surface hydrophobicity. EtOH enhanced the emulsifying properties of albumin compared with ND (22.9 versus 26.8 m 2 /g, p < 0.05). In globulin, however, HIUS promoted intermolecular disulfide bond formation, leading to aggregation and reduced flexibility, which slightly decreased emulsifying performance. In contrast, SCO₂ caused minimal functional changes, comparable to hexane and closest to ND ( p > 0.05). Overall, SCO 2 and EtOH combined or not with emerging technologies present a more environmentally friendly and promising alternative to conventional hexane-based defatting. • Defatting significantly improved the extraction recovery of coconut proteins, especially globulin from 24.9 % to 28.4 %. • All the defatting increased the surface hydrophobicity of both protein fractions. • A strong correlation (|R| > 0.7) was observed between defatting solvent polarity and protein functional properties. • HIUS defatting alters the aggregation and emulsification of coconut protein. • SCO₂ caused minimal functional changes, comparable to hexane and closest to ND.