Mechanism of non-emulsifying system establishment by NaCl soaking-microwave combined with hexanoic acid in aqueous enzymatic extraction of peanut oil.

Application of aqueous enzymatic extraction (AEE) for peanut oil is hindered by severe emulsification. This study investigated the synergistic effects of NaCl-soaking-microwave (SMW) pretreatment and hexanoic acid (HA) on non-emulsifying AEE and elucidated the mechanisms. SMW disrupted oil body membrane, induced interfacial protein degradation, altered secondary structures, promoted tertiary structure unfolding, and increased surface hydrophobicity, thereby promoting their migration to dreg phase (73.55%). HA further affected lipid molecular arrangement and bound to 18-kDa oleosin (binding energy: -3.84 kcal/mol). These synergistic effects promoted extensive oil droplets coalescence as observed by CLSM of slurries. The residual emulsion exhibited reduced stability with a tendency toward phase inversion, decreased |ζ-potential|, and increased Z-average diameter. Ultimately, SMW combined with 1.5% HA eliminated emulsion formation (from 28.28% to 0%) and increased free oil recovery from 0% to 94.03%. These findings support active suppression of emulsion formation and the development of a non-emulsifying AEE system.