Predict the Gelling Properties of Alkali-Induced Egg White Gel Based on the Freshness of Duck Eggs

Preserved egg white (PEW) has excellent gelling properties but is susceptible to the freshness of raw eggs. In this study, the correlation between the comprehensive freshness index (CFI) of raw eggs and the gelling properties of alkali-induced egg white gel (EWG) was elucidated. Results showed that the CFI, established by a principal component analysis (PCA) and stepwise regression analysis (SRA) methods, can be used to predict the freshness of duck eggs under storage conditions of 25 °C and 4 °C. A correlation analysis demonstrated that the CFI showed a strong negative correlation with the hardness and chewiness of alkali-induced EWG and a strong positive correlation with resilience within 12 days of storage at 25 °C and 20 days at 4 °C (p < 0.01). It might be due to the decrease in α-helix and disulfide bonds, as well as the hydrophobic interactions showing a first decrease and then an increase within the tested days. This study can provide an important theoretical basis for preserved egg pickling.