Differential inactivation of Listeria monocytogenes by D- and L-lactic acid.
OBJECTIVE
To determine inactivation of Listeria monocytogenes by the two lactic acid isomers.


RESULTS
The survival of four strains with varying sensitivity to acid was determined following treatment with L- or D-lactic acid at 100 mmol l(-1) (pH 3.7) or HCl at pH 3.37. There was some, but not complete, similarity in the relative sensitivity of the four strains to the two types of acid. All strains were most sensitive to D-lactic acid, which gave 0.6-2.2 log units greater reduction than L-lactic acid midway in the inactivation curves. Even very low concentrations of the two isomers had an immediate effect on pH(i) which was identical for the two isomers.


CONCLUSIONS
The results show that L. monocytogenes is more sensitive to D- than to L-lactic acid; however, this difference is less than the strain variation in L-lactic acid sensitivity.


CONCLUSIONS
This work has implications for the application of lactic acid for food preservation as well as for the understanding of the antibacterial mechanisms of weak organic acids.
Gravesen
A
A
Department of Food Science, Centre of Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark. alg@kvl.dk
Diao
Z
Z
Voss
J
J
Budde
B B
BB
Knøchel
S
S
D015169:Colony Count, Microbial; D003593:Cytoplasm / Q000737:chemistry; D005516:Food Microbiology; D005520:Food Preservatives / Q000737:chemistry / Q000494:pharmacology; D006851:Hydrochloric Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry* / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects*; D013237:Stereoisomerism
D005520:Food Preservatives; D019344:Lactic Acid; D006851:Hydrochloric Acid