Inactivation of Staphylococcus aureus in phosphate buffered saline and physiological saline using ohmic heating with different voltage gradient and frequency

Ohmic heating (OH), an alternative thermal processing technique, has various applications in food industry in recent years. To better understand the inactivation of microorganisms treated with OH, effects of OH with different voltage gradient (5 and 10 V/cm) and frequency (50 and 500 Hz) on the inactivation of Staphylococcus aureus in physiological saline (PS) and phosphate buffered saline (PBS) were determined in this study. The temperature and electric current were also recorded during heating process. Water bath heating (72 °C, WB) was also carried out and served as control. A similar complete death temperature was observed in OH and WB treatments, which illustrated that OH could effectively inactivate S. aureus. The results indicated that OH treatments reduced the population of injured cells, and 10 V/cm 50 Hz treatment had the greatest degree of reduction. Compared to PS, PBS exhibited a protective effect on the inactivation of S. aureus treated with OH.