Ohmic heating as a method of obtaining paraprobiotics: Impacts on cell structure and viability by flow cytometry

This study aimed to evaluate the effects of ohmic heating (OH) on probiotic inactivation, cell viability and morphology of the probiotic strains Lactobacillus acidophilus LA 05 (LA), Lacticaseibacillus casei 01 (LC), and Bifidobacterium animalis Bb 12 (BA) to develop paraprobiotics. OH at different electric field magnitudes (4, 8, and 12 V/cm at 60 Hz) and conventional heat treatment (CONV) were performed to determine the most adequate condition for the obtainment of paraprobiotics. Analysis of culturability, flow cytometry (FC), and Scanning electron microscope (SEM) was carried out. The complete inactivation by CONV was achieved only in the following conditions: LA - 95 °C/5 min, LC and BA - 95 °C/7 min. The same temperature profile was used in OH treatments to study the OH electrical effects. The OH treatment (8 V/cm) caused lower damage to the cell membrane integrity compared to the CONV treatment (p < 0.05). The OH showed to be adequate technology for the efficient production of paraprobiotics.