Lecithin regulates the frozen-thawed egg yolk gelation behaviour and its underlying mechanism

This research investigated the effects of lecithin concentration on the gelation behaviors of egg yolks (EYs) during freeze-thaw cycles and explored the underlying mechanisms. The emulsifying and gelation properties, particle size, turbidity, solubility, and structural characteristics of frozen-thawed EYs treated with lecithin were systematically analyzed. Lecithin treatment was found to enhance emulsifying activity and solubility while reducing particle size and turbidity. Compared with the control sample, lecithin addition led to a reduction in breaking force (from 81.86 to 65.25) and surface hydrophobicity (from 4199.3 to 2448.3), the yolk consistency was decreased, the fluidity was increased. Structural analysis indicated an elevation in β-turn content, decreases in α-helices and β-sheets, and a redshift in the λmax value, indicating that lecithin mitigated freezing-induced protein unfolding and denaturation while exposing buried tryptophan residues to hydrophilic environments. Confocal laser scanning microscopy confirmed that lecithin treatment reduced particle size and inhibited protein aggregation. These findings suggest that lecithin can suppress the gelation of frozen-thawed EYs by modulating protein structure and interactions. • Lecithin can inhibit the structure changes of egg yolk protein. • Lecithin can increase frozen thawed egg yolk emulsification and reduce its gelation. • Less than 0.5% lecithin promoted the frozen-thawed EYs aggregation • Higher than 0.5% lecithin inhibited the frozen-thawed EYs aggregation to some extent.