Modelling the behaviour of Listeria monocytogenes in ground pork as a function of pH, water activity, nature and concentration of organic acid salts

Abstract

to study and model the effect of sodium acetate, sodium lactate, potassium sorbate and combination of acid salts on the behaviour of Listeria monocytogenes in ground pork. Water activity (a(w)), pH and concentration of acid salt of the meat were adjusted. The behaviour of inoculated L. monocytogenes was studied and modelled according to physicochemical parameters values. Whatever the acid salt concentration used, we observed an inhibition of the growth of L. monocytogenes at pH 5.6 and a(w) 0.95. At pH 6.2 and a(w) 0.97, addition of 402 mmol l(-1) of sodium lactate or 60 mmol l(-1) of potassium sorbate was required to observe a slower growth. The inhibitory effect of acid salts was a function of pH, a(w), as well as of the nature and concentration of acid salts added. When one acid salt was added, the Augustin's model (Augustin et al. 2005) yielded generally correct predictions of either the survival or growth of L. monocytogenes. The suggested model can be used for risk assessment concerning L. monocytogenes in pork products.