Inactivation effect and action mode of ohmic heating on Staphylococcus aureus in phosphate‐buffered saline

Abstract

Ohmic heating (OH) is an alternative thermal processing technique, which shows large potential application in pasteurization. Inactivation effect and sublethal injury of OH on Staphylococcus aureus were investigated in this study. Meanwhile, membrane potential and integrity, bacterial morphology and the leakage of nucleic acid, protein and ions were also measured to elucidate the action mode of OH. When heated to 50°C, OH treatment showed higher injury ratio than water bath (WB) treatment. Meanwhile, greater loss of cellular content, larger reduction of membrane potential, and severer damage to cell morphology and membrane integrity were observed in OH‐treated S. aureus than that of WB. When heated to 61.5°C, there was no significant difference between OH‐ and WB‐treated S. aureus. Results indicated that OH caused more sublethal injury and server damage to S. aureus than that of WB when heated to a lower temperature (50°C).