The Impact of Instantaneous Ultra-High Temperature (INF) Versus Conventional Thermal Processing on Bovine Milk: Nutritional and Physicochemical Perspectives

Balancing microbial safety and the retention of heat-sensitive components has long been a key issue in dairy processing research. This study systematically compared the effects of instantaneous ultra-high-temperature treatment (INF, 145-155 °C/0.09 s) with that of conventional pasteurization (75-95 °C/15 s) as well as ultra-high-temperature treatment (UHT, 135 °C/5 s), on the microbial evaluation, nutritional composition, and physicochemical quality of bovine milk. The results showed that all heat treatments completely inactivated <i>Staphylococcus aureus</i>, <i>coliforms</i>, while only UHT and INF achieved full spore elimination. In the INF group, α-lactalbumin remained almost completely native and native β-lactoglobulin retention was approximately 83% relative to raw milk. The retention of lactoferrin and immunoglobulin G was about 30% and 12% after INF treatment, respectively, which were higher than that of 13% and 8% in the 85 °C/15 s group, and complete denaturation in the 95 °C/15 s and UHT groups. Furthermore, vitamin B₂ remained stable after INF treatment. The glycation content of proteins was lower in INF treatment compared to conventional heat treatments, especially for the concentration of furosine, which was about 6-7 mg/100 g protein in the INF group, and 15 mg/100 g protein in the 95 °C/15 s group, and 67 mg/100 g protein in the UHT group. Overall, the INF process achieved sterilization equivalent to UHT while substantially reducing thermal load, thus better balancing microbial safety, nutritional integrity, and immune-active proteins, which provides a scientific basis for establishing standardized INF parameters and promoting high-quality dairy production.