The objective of the current study is to identify the influence of acidity on ohmic heating compared to
conventional heating for inactivation of food-borne pathogens in orange juice.
For conventional heating,the heating rate was not significantly different (P > 0.05) regardless of pH and pathogens were inactivated more effectively at lower pH.
However, different patterns were observed for ohmic heating.
Although temperature and electrical conductivity were not greatly affected by lowering pH, temperature
increased more rapidly with increasing pH due to higher electrical conductivity. Also, the inactivation
patterns were significantly different (P < 0.05) from conventional heating. While Salmonella Typhimurium
was inactivated most rapidly at pH 2.5, Escherichia coli O157:H7 and Listeria monocytogenes were
inactivated most rapidly at pH 4.5. When pathogens were exposed to each heating method at a fixed
temperature, additional effects of ohmic heating were not observed. Also, the overall quality of orange
juice subjected to ohmic heating was not greatly affected at any pH level. Therefore, increasing as well as
lowering pH can also be considered effective ways to optimize pasteurization of orange juice when using
ohmic heating. The different characteristics of ohmic heating compared to conventional heating indicate
the necessity of a new approach