关键词: 蛋清蛋白；球磨处理；起泡性；结构性质

Abstract: Egg white is widely used in bakery food processing because of its excellent foamability. Therefore, it is of great significance to improve the foamability of egg white proteins. In this experiment, the free sulfhydryl content, surface hydrophobicity, hydrolysis degree, zeta-potential and particle size of egg white proteins were measured after ball-milling treatment, and their thermodynamic properties, secondary structure, foaming characteristics and microstructure were analyzed. The aim was to investigate the effects of ball milling on the structural and foaming properties of egg white proteins. The results showed that ball milling resulted in no significant change in the foaming capacity of egg white proteins, while the foam stability showed a trend of increasing and then decreasing, reaching the maximum value (33.5 s) at 40 min of ball milling treatment, which was nearly four times higher than that of the control group. In addition, ball milling treatment significantly reduced the surface hydrophobicity and denaturation enthalpy (ΔH) of egg white proteins (P < 0.05), increased the hydrolysis degree, particle size and decrease the absolute value of zeta-potential (P < 0.05), but had no significant effect on the free sulfhydryl content or denaturation temperature (P > 0.05). The proportion of β-sheet conformation continued to significantly increase (P < 0.05), the proportion of α-helix declined initially and then rose, while the proportion of β-turn first increased and then decreased with increasing time of ball milling. Scanning electron microscopy (SEM) showed that ball milling treatment caused fragmentation and flocculation of egg white protein particles in a scattered manner. In conclusion, moderate ball milling treatment can change the molecular structure of egg white proteins and thus improve their foaming stability.

Key words: egg white proteins; ball-milling treatment; foaming properties; structural properties