Effect of ascorbic acid, in comparison to citric and lactic acids on Listeria monocytogenes inhibition at refrigeration temperatures

GIANNUZZI L; ZARITZKY NOEMI.

LEBENSMITTEL-WISSENSCHAFT UND-TECHNOLOGIE-FOOD SCIENCE AND TECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 1996 vol. 29 p. 278 - 285

0023-6438

This study analysed the effect of pH (3.0?6.5) as given by ascorbic acid in comparison to citric and lactic acid at refrigeration temperatures (4 and 10°C) on the inhibition and survival of Listeria monocytogenes in trypticase soya broth with yeast extract.Gompertz model was used to obtain microbial growth parameters and a linear model was fitted in the cases of bacteriostatic and bactericidal action of the acids. For each acidifier, results were expressed as a function of the undissociated acid concentration (u.a.c.). Ascorbic and lactic acid produced a decrease in the initial microbial counts. Two indices were defined in order to analyse the influence of the acids: the inhibitory effect and the inhibition index. The inhibitory effect values showed the effect on the slopes of growth and lethality curves and inhibition index included the influence on lag phase duration. At pH 4 ascorbic acid producedhigher inhibitory action than citric and lactic acid which can be attributed to the higher pKa value of ascorbic acid. However, if the analysis is based on u.a.c., citric acid was more effective because with lower concentration higher indices were obtained.