This report also focuses on self-conducted research using ohmic heating to determine its
effect on Lactobacillus acidophilus inactivation versus conventional heating. Lactobacillus
acidophilus was inoculated into MRS broth and incubated for 24 hours. The sample was then
inoculated into sterile buffer at a dilution rate of 1:100. Samples of the diluted culture were
subjected to either low voltage (18 V) or conventional heating (300°C) over a hotplate stirrer.
Temperature was monitored on test and control samples to achieve an endpoint of 90°C.
Samples were taken at regular intervals, plated onto MRS agar and incubated for 72 hours at
35°C to compare plate count expressed as colony forming units per milliliter (cfu/mL).
Temperature was uniform throughout the ohmically heated sample and reached the endpoint
more quickly than the conventionally heated sample, which also had cold spots. The total plate
count at the end of the experiment was less for the ohmically heated sample versus the
conventionally heated sample. Ohmic heating was more effective in inactivation of Lactobacillus
acidophilus than conventional heating, most likely due to the more rapid and uniform heating of
the sample, and possible electroporation of the cells.