Application of high-voltage electrospray system for non-thermal microbial inactivation of raw bovine milk

High-voltage electrospray (ES) was applied for non-thermal microbial inactivation of raw bovine milk (RBM). The ES treatment was performed at 20-80 kV voltage range; 0.2-0.8 mL min-1 feed flow rate; 25-32 G needle diameter; and 1-4 running cycles. At the 20-30 kV voltage range, ES did not achieve satisfactory microbial inactivation on RBM (0.5-1.5 logarithms). At 50 kV, the ES treatment inactivated 2.31 logarithms of bacterial cells present in RBM, which was comparable to the bacterial inactivation achieved by low-temperature long-time pasteurization (LTLT; 63 degrees C for 30 min; 2.3 logarithms) and was better than high-temperature short-time pasteurization (HTST; 72 degrees C for 15 s; 2.2 logarithms). The bacterial inactivation caused by the high-voltage ES system was found to be due to the damage to cell membrane and subsequent leakage of nucleic acids and other intracellular substances. Compared with the thermally pasteurized milk, ES-treated samples retained higher percentage of soluble protein content and aromatic volatile organic compounds. The shelf life of RBM was extended to 14 days at 4 degrees C (Escherichia coli was not detected) when ES was carried out at 80 kV. This was 8 days longer than the shelf life achieved by LTLT pasteurization and 6 days longer than the shelf life of HTST pasteurized milk.