Modelling the piezo-protection effect exerted by lactate on the high pressure resistance of Listeria monocytogenes in cooked ham

Unravelling the Molecular Mechanisms Underlying the Protective Effect of Lactate on the High-Pressure Resistance of Listeria monocytogenes

“…In the presence of lactate in the CHMM, HPP resulted in a lower inactivation of the strains, recording 0.44 ± 0.04 and 2.36 ± 0.22 Log reduction for CTC1034 and EGDe, respectively. In particular, for the CTC1034 strain, the lethal effect of HPP was lower ( p < 0.05) in the presence of lactate, corroborating the piezo-protective effect of this antimicrobial on L. monocytogenes inactivation as previously shown for this and other strains inoculated in different types of meat products [ 9 , 10 , 30 , 31 ].…”

“…The higher expression of the methionine biosynthesis pathway by L. monocytogenes exposed to lactate and the inhibition of the biosynthesis of this amino acid by acetate reported for E. coli [ 50 ] could be the reason why the piezo-protective effect on L. monocytogenes treated at 400 MPa for 10 min was only seen for cooked ham formulated with lactate and not with diacetate [ 10 ]. Further studies regarding L. monocytogenes membrane functionality (membrane composition, fluidity, and integrity) as a function of the exposure of lactate and the application of the HPP need to be conducted to experimentally to confirm the role of the membrane properties on the piezo-protective effect exerted by lactate on HPP inactivation of L. monocytogenes .…”

“…Strains of L. monocytogenes used in the present study included two different serotypes with relevance from the clinical and from the food and food processing environment perspective [ 12 ]. The meat isolate CTC1034 (serotype 4b) from the IRTA Food Safety Program’s collection and previously used in studies dealing with the application of HPP in meat products [ 10 , 11 , 13 , 14 ] and the L. monocytogenes strain EGDe (serotype 1/2a) as a reference strain. For this study, three biological replicates of each strain were prepared from −80 °C stock cultures.…”

“…Chromogenic media for L. monocytogenes are known to be able to recover high pressure injured L. monocytogenes [ 16 , 17 ]. In any case, plates were further checked after additional 24–48 h to make sure that sub-lethally injured cells had time to recover and form colonies and, thus, minimize the overestimation of the lethal effect of HPP [ 10 , 11 ]. L. monocytogenes counts were Log transformed, and the inactivation value in terms of Log reduction was calculated by subtracting from the counts found in non-pressurized cultures (Log N 0 ) those of the pressurized cultures (Log N), i.e., LogN 0 − LogN = Log N 0 /N, both in the control and 2.8%-lactate lots.…”

“…Few studies have been conducted dealing with the effect of combination of strategies (i.e., HPP and organic acids) on L. monocytogenes in meat products [ 4 , 9 ]. Interestingly, Serra-Castelló et al [ 10 ] showed that the HPP inactivation of three L. monocytogenes strains (CTC1034, CTC1011 and Scott A) in cooked ham formulated with potassium lactate was lower than in cooked ham without this antimicrobial. This piezo-protective effect was quantified showing it was strain and lactate dose-dependent.…”