Differences in protein composition and functional properties of egg whites from four chicken varieties

Egg white protein (EWP) is widely used in the food industry for its technological properties, which are affected by diet- and breed-related changes in its composition. Therefore, the objective of this study was to analyse the relationship between hen variety and the protein composition, functional characteristics, and physicochemical properties of egg white (EW) obtained from Black Bone (BB), Gushi (GS), Hy-Line (HY-LINE), and Harbin White (HW) chickens. The protein composition of EW was analysed by high performance liquid chromatography (HPLC), while the secondary structure of EWP was assessed by Raman spectroscopy. BB and GS EWs had significantly higher ovalbumin content (183.38 and 168.56 μg/mL, respectfully) than HY-LINE and HW EWs (148.15 and 147.44 μg/mL, respectfully) (p < 0.05). In accordance with the higher ovalbumin content, BB and GS EWs possessed significantly better foaming and gel properties, along with greater sulfhydryl group and disulfide bond content in the EWPs, than HY-LINE and HW EWs (p < 0.05). Additionally, the ovotransferrin, ovomucin, and lysozyme contents also differed significantly among EWs from the four varieties (p < 0.05). Further, the EWPs possessed significant differences in amino acid (AA) content, including essential AAs, those contributing to egg flavour, and those associated with children's growth and preterm infant health. In conclusion, differences in protein composition likely led to dissimilar functional and physicochemical properties among EWs obtained from different hen varieties, which could provide a reference for food production and genetic breeding of laying hens. • The protein composition of EW was analysed by high performance liquid chromatography (HPLC). • The EWPs possessed significant differences in amino acid and protein content. • Differences in protein composition likely led to dissimilar functional and physicochemical properties. • Egg whites from Black Bone and Gushi chickens might be more suitable for industrial food production.