Modification of liquid egg yolk with phospholipase A2-hydrolyzed yolk granules: thermal stability and interfacial...

Thermal treatment of liquid egg yolk promotes lipoprotein denaturation and aggregation, resulting in increased viscosity and impaired emulsifying properties. This study investigated whether phospholipase A2-hydrolyzed egg yolk granules (PLA2-HEYG) could improve the thermal stability and interfacial functionality of recombined egg yolk liquid.

Native egg yolk was recombined with 0-200 g kg^-1 PLA2-HEYG and heated at 75 °C for 7 min. Increasing the PLA2-HEYG level reduced the apparent viscosity of both unheated and heated samples and progressively suppressed heat-induced aggregation. After heating, the volume-weighted mean particle diameter D[4,3] decreased from 904.163 μm in the control (TH0) to 5.764 μm and 2.207 μm at 150 and 200 g kg^-1 PLA2-HEYG, respectively, corresponding to decreases of 99.36% and 99.76%. Confocal microscopy further showed fewer large aggregates at higher PLA2-HEYG levels. The addition of PLA2-HEYG also reduced the contact angle and interfacial tension, indicating improved interfacial properties. After heating, emulsifying capacity increased with PLA2-HEYG addition; the sample containing 200 g kg^-1 PLA2-HEYG reached 111.25 mL, comparable to unheated native egg yolk (110 mL) and 51.36% higher than the heated control. Emulsifying stability also increased with PLA2-HEYG addition, whereas emulsifying activity increased at lower addition levels and then decreased slightly.

Incorporating PLA2-HEYG, particularly at 150-200 g kg^-1, effectively suppressed heat-induced aggregation and preserved the interfacial and emulsifying functionality of liquid egg yolk during thermal treatment, demonstrating its potential for improving the thermal processability of egg yolk products. © 2026 Society of Chemical Industry.