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Hurdle technology approach to control Listeria monocytogenes using rhamnolipid biosurfactant

Journal Contribution - Journal Article

This study evaluates the combination of mild heat with a natural surfactant for the inactivation of L. monocytogenes Scott A in low water activity (aw) model systems. Glycerol or NaCl was used to reduce the aw to 0.92, and different concentrations of rhamnolipids (RL) biosurfactant were added before heat treatment (60 °C, 5 min). Using glycerol, RL treatment (250-50 µg/mL) reduced bacterial population by less than 0.2 log and heat treatment up to 1.5 log, while the combination of both hurdles reached around 5.0 log reductions. In the NaCl medium, RL treatment displayed higher inactivation than in the glycerol medium at the same aw level, and a larger synergistic lethal effect when combined with heat, achieving ≥ 6.0 log reductions at 250-10 µg/mL RL con-centrations. The growth inhibition activity of RL was enhanced by the presence of the monova-lent salts NaCl and KCl, reducing MIC values from >2,500 µg/mL (without salt) to 39 µg/mL (with 7.5% salt). The enhanced antimicrobial activity of RL promoted by the presence of salts showed to be pH-dependent and more effective under neutral conditions. Overall, results demonstrate that RL can be exploited to design novel strategies based on hurdle approaches aiming to control L. monocytogenes
Journal: Foods
ISSN: 2304-8158
Issue: 3
Volume: 12
Publication year:2023
Accessibility:Open