Natural creaming significantly modulates the metabolomic profile and bacterial community of raw milk: A case study on organic milk for Parmigiano Reggiano PDO

This study analyzed raw milk's microbial community and chemical profile during the natural creaming process of Parmigiano Reggiano production by comparing milk from farms following two different organic certifications. Specifically, the natural creaming process underlined the positive accumulation of potentially pro-dairy bacteria, particularly those of the genera Lactococcus and Streptococcus, and a significant reduction of negative bacterial genera, such as Acinetobacter and Rothia, in the final mix milk. Meanwhile, untargeted metabolomic analysis confirmed the representativeness of lipids and lipid-derivatives as chemical markers involved in the overnight creaming process, with fatty acid esters and long fatty acids enriched in the evening samples. Finally, by using a multi-omics approach, we integrated microbial and metabolomic datasets and identified correlations between specific microbial populations and metabolite changes. This integrative analysis revealed microbial-metabolite interactions that may be a starting point to better understand the pivotal role exerted by milk creaming on the final cheese quality.