A holistic approach to understand flavor formation and loss during milk protein concentrate production: impact of processing on volatile and fatty acid profile

The rising demand for high-protein products highlights the importance of milk protein concentrate (MPC) as a key ingredient. This study investigated how end-to-end MPC production impacts fatty acid and volatile profiles. Fatty acid profiles remained largely unchanged, while concentrations decreased during later processing stages, likely due to oxidative degradation. A total of 43 volatile compounds were quantified across all milk concentrates and permeate samples. Hexanal was found at higher concentrations in the final MPC powder compared to liquid MPCs, consistent with lipid oxidation during processing and spray drying. In contrast, octanoic and decanoic acids decreased during membrane processing due to partitioning to the permeate fraction. Octanoic acid was negatively correlated with 1-octanol, suggesting degradation via α-scission of oleic acid, whereas decanoic acid was potentially adsorbed to the membrane. Nonanoic acid was potentially formed during membrane filtration via enzymatic lipolysis, as no correlation with oleic acid was observed. Ethyl butyrate, ethyl propanoate, ethyl hexanoate, ethyl decanoate, octanal, and hexanoic acid showed significant positive correlations with unsaturated fatty acids, potentially indicating lipid oxidation as a major pathway for flavor formation during MPC production. Collectively, these findings demonstrate flavor migration and oxidation-driven formation throughout processing and underscore the need for process optimization to retain desirable flavors in MPC.