Research note: Changes in chicken egg yolk metabolome during its spray drying and storage.

The differences in metabolites between fresh egg yolk (FEY), spray-dried egg yolk powder (SEY), and stored egg yolk powder (S-SEY) were quantitatively compared through metabolomic analysis. Total of 1004 metabolites were identified in the three groups of egg yolk samples. In pairwise group analysis, 242 differential metabolites were identified in FEY and SEY, 311 differential metabolites were identified in FEY and S-SEY, and 157 differential metabolites were identified in SEY and S-SEY. The analysis of differential metabolites with the highest abundance showed that amino acids, carbohydrates and lipids in FEY would undergo oxidation reactions after spray drying and storage and thus led to significant changes in the type and abundance of metabolites. The representative differential metabolites were then screened out for judging the freshness of egg yolk powder. Therefore, the results are highly important for evaluating the quality of egg yolk powder and provide important information for understanding the nutritional changes of egg yolk after spray drying and storage.