Pulsed electric field treatment of Lacticaseibacillus rhamnosus and Lacticaseibacillus paracasei, bacteria with probiotic potential

Lactic acid bacteria play an important role in functional food and fermentation products for human and animal nutrition, as probiotics, paraprobiotics, postbiotics or high-lactic acid-producing strains in biorefineries. Pulsed electric field (PEF) treatment is gaining recognition in the food industry, but little is known about the effects of PEF treatment on the probiotic characteristics of lactic acid (LA) bacteria or its application for the production of paraprobiotics and postbiotics. Thus, we studied the inactivation kinetics and permeabilization of Lacticaseibacillus rhamnosus and Lacticaseibacillus paracasei as high LA-producing strains with probiotic characteristics by batch and continuous PEF treatment. Significant linear correlations between the logN reduction and permeabilization of the studied bacteria and specific energy input and current were observed during PEF treatment. Sublethal PEF treatment (5 kV/cm, 8 x 1 ms, 1 Hz) induced 10% higher LA production in L. rhamnosus, as well as the release of proteins from both bacteria. Sublethal PEF treatment did not change the susceptibility to specific antibiotics in L. rhamnosus, while L. paracasei showed some decrease in susceptibility to antibiotics. The results obtained are valuable for PEF treatment of functional food with probiotics and the production of paraprobiotics and postbiotics to improve food safety and functionality.