Volatile Compounds, Fatty Acid Profile, and Technological Properties of A1 and A2 Bovine Milk: Effect of Pasteurization Method

A2 milk has recently gained popularity, mainly due to its different beneficial effects on the human digestive system compared to popular A1 milk. Because of these structural differences, A2 milk exhibits characteristics that need to be investigated to design processes appropriately. The effects of β-casein genotype and heat treatment method (LTLT, HTST, and HTLT: a high-temperature preparatory treatment applied in fermented dairy production) on the fatty acid profile, volatile organic compounds (VOCs), composition, emulsion stability, acidification kinetics, and color parameters were investigated. Fatty acid composition was determined exclusively by milk type. A1 milk exhibited higher saturated fatty acids, higher total PUFA content, higher Σn-3 fatty acids, and a more favorable n-6/n-3 ratio, while A2 milk showed higher monounsaturated fatty acids and higher CLA (Conjugated Linoleic Acid) in a trait-dependent manner. VOC profiling identified 29 compounds. Significant genotype × treatment interactions were observed: A1 milk was characterized by high diacetyl in fresh samples and exclusive methanethiol formation upon pasteurization, while A2 milk showed enhanced Maillard-derived volatile formation and high ester accumulation after LTLT treatment. Emulsion stability was highest after LTLT treatment regardless of milk type. A1 milk reached the coagulation threshold of pH 4.6 within 45 min, whereas A2 exhibited delayed acidification. HTLT induced the greatest color changes in both types of milk.