Effects of short-term fermentation with lactic acid bacteria on the characterization, rheological and emulsifying properties of egg yolk

Lactic acid bacteria fermentation is a safe and green technology that can modify the function of food ingredients (including proteins). In this article, egg yolks were subjected to fermentation with commercial lactic acid bacteria for 0, 3, 6 and 9 h, respectively. After fermentation treatment, the microbial composition has changed obviously (Streptococcus thermophilus increased significantly). The free sulfhydryl group (SH) contents and surface hydrophobicity of egg yolk proteins were significantly reduced. The rheological results indicated that the treated egg yolks possessed a decreased apparent viscosity. Correspondingly, the emulsifying activity of egg yolk was enhanced from 9.07 to 19.55, 23.40 and 24.61 m(2)/g for 3, 6 and 9 h of fermentation, respectively. And the emulsifying stability reached the maximum after 3 h of fermentation. This study investigated the relationship between structure and properties of yolk proteins, and showed that lactic acid fermentation endued egg yolk with better emulsifying properties.