Unravelling the interaction between feeding regimens and milking time in Parmigiano Reggiano PDO milk: an integrated metabolomics and ion mobility lipidomics approach

In this study, an integrated approach based on UHPLC-HRMS metabolomics and IM-HRMS lipidomics has been carried out to unravel the interaction between feeding and milking time in the overall chemical profile of Parmigiano Reggiano (PR) milk. Specifically, ANOVA multiblock OPLS (AMOPLS) modelling revealed the complementarity of the assays in combining the effect of these two critical parameters. In particular, metabolomics highlighted the presence of plant-derived compounds (mainly terpenoids and phenolic compounds) in grass-enriched milk compared to those produced with a more intensive alfalfa-based diet. Conversely, lipidomics highlighted significant changes in morning milk that involved di- and triacylglycerols, ceramides, and sphingomyelins enrichment. The expression of these lipids is linked to the structure of milk fat globules, which are influenced by diet and feeding access during the circadian cycle. This work underscores the complexity of milk composition and provides a basis for understanding the critical role of milking time in milk quality.