Changes in physicochemical properties, molecular structure and microstructure during vacuum assisted quick pickling of low-NaCl salted eggs

In order to clarify the quality formation process of low-NaCl salted eggs (LSEs) under the dual action of vacuum and salt, changes of physicochemical properties, molecular structure, and microstructures of egg white as well as interior and exterior yolks were systematically studied. Results showed that the salt content of egg whites and egg yolks increased to around 5% and 1% respectively, which were only about half of their traditional counterparts. Exterior yolk exudes more oil than the interior yolk, which was consistent with the observation of a more compact microstructure by scanning electron microscopy (SEM). Rheological testing demonstrated a significant increase in the viscosity of yolks but a decrease of egg whites. At the molecular level, proteins of egg white and yolk had gone through the process of denaturation and aggregation, but their change tendencies of free sulfhydryl group, surface hydrophobicity and secondary structure were slightly different. In summary, vacuum assisted two-stage pickling could effectively shorten the ripening time of salted eggs and reduce salt content without compromising their good quality.