Exploring the potential of microwave processing for improved microbial safety and nutritional quality of liquid milk

This study systematically compared the effects of microwave (MW) and conventional thermal (CT) processing on microbial inactivation, enzyme activity, protein retention, and nutritional characteristics of bovine milk under pasteurization (70 °C for 20 s) and ultra-high temperature (UHT) sterilization conditions. Both technologies achieved effective microbial reduction (>4 log CFU/mL) for Escherichia coli, Staphylococcus aureus, and Salmonella spp., complying with EU and FDA safety standards. Enzymatic analysis demonstrated MW treatment preserved 12.9 % higher lactoperoxidase (LPO) activities than CT processing at 80 °C for 15 s, suggesting enhanced preservation of native enzyme systems. It is noteworthy that MW treatment improved the retention of whey proteins compared to the CT method, particularly lactoferrin (LF), which has a lower thermal denaturation temperature than the sterilization temperature. Specifically, LF retention increased by approximately 12 % when MW treatment was applied within the pasteurization safety range. Furthermore, MW processing enhanced protein digestibility, as shown by accelerated β-lactoglobulin (β-Lg) degradation during gastric digestion, which might mitigate allergic reactions associated with whey protein ingestion. The study also explored the bioactive peptide release during digestion and its subsequent antioxidant activity, finding no significant difference between MW and CT processing. Finally, cell viability assays confirmed that MW-processed milk digestion products maintained high intestinal epithelial cell viability, suggesting that MW transient heating could serve as an effective alternative to conventional methods while preserving both safety and nutritional value. The findings underscored the potential of MW processing for improving milk safety, protein retention, and functional properties in liquid milk production.