Quantitative N-glycoproteomic analyses provide insights into the effects of thermal processes on egg white functional properties.

This study tries to elucidate the different mechanisms of functional properties among pasteurized egg white (P-EW), spray-dried egg white (SD-EW) and fresh egg white (F-EW) via quantitative N-glycoproteomic analyses. The results showed that spray-drying increased the surface hydrophobicity (181.4%) and zeta potential (25.6%) of egg white, which contributed to the enhancement of emulsifying activity index (20.1%) and foaming capacity (35.2%). Pasteurization caused the disintegration of natural protein aggregates in F-EW and resulted in a "block-like" P-EW gel and higher water holding capacity (6.2%). Spray-drying caused formation of thermal aggregates and led to a "mesh-like" SD-EW gel and better cohesiveness (3.6%). Quantitative N-glycoproteomic analysis showed that the abundance of 32 N-glycosites from 18 N-glycoproteins (such as Mucin 5B) of SD-EW was significantly reduced comparing to F-EW, indicated that the N-glycans of egg white protein are likely to be covalently cross-linked during spray-drying and are involved in thermal aggregation.