Unraveling the impact of protease hydrolysis on the gelation properties of whole egg liquid: physicochemical, textural and structural characteristics.

Abstract

Background: Egg proteins are of high quality with excellent gelation properties. This study explored how neutral protease hydrolysis (400, 800, 1200 U g^-1) and heating time (10, 20 min) affect whole egg liquid (WEL) gelation, focusing on protein solubility, intermolecular interactions and gel structure changes for food applications.

Results: Enzymatic hydrolysis significantly increased the degree of hydrolysis, with higher enzyme dosage (up to 1200 U g^-1) leading to enhanced protein solubility (from 81.09% to 93.21%) and reduced average particle size (from 476 to 80 nm). Texture analysis showed that higher enzyme levels reduced the breaking force and distance to rupture, while prolonged heating time (20 min) could increase breaking force, such as increasing the 1200 U g^-1 sample from 17.4 to 23.27 g. Fourier transform infrared spectroscopy showed that enzymatic hydrolysis raised β-sheet content (from 43.62% to 43.98%) but reduced β-turn, whereas prolonged heating shifted β-sheet to β-turn. Intermolecular force analysis indicated dominant hydrophobic interactions in control gels, while enzymatically treated gels exhibited increased ionic bonds and hydrogen bonds. Scanning electron microscopy demonstrated that enzymatic hydrolysis and longer heating produced denser, more uniform gel networks.

Conclusion: Protease hydrolysis and heating time greatly modulate WEL gel properties. Enzymatic treatment makes gels softer, while longer heating improves hardness and microstructure. These findings can guide tailoring of WEL gel properties for industrial uses like custards by optimizing conditions. © 2025 Society of Chemical Industry.