Effect of pre-treated homogenized egg liquid addition on yogurt quality and metabolic profiles

This study prepared yogurt by adding pre-treated egg liquid to milk to modify the texture and nutritional composition, and systematically analyzed the effects of fermentation and egg liquid addition on yogurt metabolites. Results showed that the addition of pre-treated egg liquid significantly improved the nutritional value of both milk and yogurt, enhanced the sense of thickness in taste, and resulted in a more compact microstructure. A total of 935 metabolites were identified through metabolomics analysis. Compared with ordinary yogurt, the abundance of "amino acids and its metabolites", "organic acid and its derivatives", "glycerophospholipids", and "fatty acyls" in egg-milk yogurt was significantly increased. Differentially abundant metabolites were mainly enriched in pathways such as "glycerophospholipid metabolism" and "ABC transporters". Specifically, the addition of egg liquid increased small peptides (e.g., γ-Glu-Phe), glycerophospholipids (e.g., LPC(0:0/22:6), LPC(0:0/20:4)), and long-chain polyunsaturated fatty acids (e.g., FFA (22:4), FFA (22:5)), which maintained a significant advantage after fermentation. These findings provide a theoretical basis and new insights for the processing of egg-dairy composite products and the development of functional yogurts.