Salt-tolerant Staphylococcus bacteria induce structural and nutritional alterations of salted duck egg white

Salted duck egg white, a major by-product of salted egg yolk production, is rich in nutrients. However, its high salinity limits its application in the food industry. In the present study, three haloduric bacterium strains (C1, C2, and C3) were isolated from Jinhua ham, and strain C1 exhibited higher ratio of the transparent circle diameter to the colony diameter (HC) and gelatin liquefaction. Strain C1 was further identified as a member of the genus Staphylococcus through gene sequencing and EzTaxon-e analyses. Salted duck egg white was fermented by strain C1, and the thermal stability, microstructure, amino acid composition, and γ-aminobutyric acid of the egg white were compared with egg white without fermentation. The fermented salted duck egg white had a significantly low salinity. Meanwhile, it increased its thermal stability compared with the control through losing an endotherm at around 85°C and forming a new endotherm peak starting at 91.8°C. Additionally, free amino acids and γ-aminobutyric acid were found only in the fermented salted duck egg white. These indicated that fermentation with salt-resistant strains could alter the structure of salted duck egg white and improve its nutritional quality.