Dynamics of physiological responses of potentially probiotic fruit-derived Limosilactobacillus fermentum in apple and orange juices during refrigeration storage and exposure to simulated gastrointestinal conditions

This study evaluated the dynamics of the physiological responses of potentially probiotic fruit-derived Limosilactobacillus fermentum 139 and L. fermentum 263 in apple and orange juice during 28 days of refrigeration storage (4 °C) and when submitted to simulated gastrointestinal conditions. Physiological responses were measured with multiparametric flow cytometry using propidium iodide (PI), carboxyfluorescein diacetate ( c FDA) and bis-1,3-dibutylbarbutiric acid (BOX). Viable counts were enumerated with plate count. L. fermentum strains had sizes of > 30% of cell subpopulations with non-permeabilized membrane and enzymatic activities (viable cells, PI- C FDA +) in apple and orange juices during storage and viable counts of > 6 log CFU ml −1 . Sizes of cell subpopulations with permeabilized membrane without enzymatic activity (dead cells, PI + cFDA−) were low ( 35%) after exposure to ileum condition and viable counts of ≥ 5 log CFU/mL. PI-BOX + cell subpopulation sizes were low (