Effect of Potassium Lactate and a Potassium Lactate–Sodium Diacetate Blend on Listeria monocytogenes Growth in Modified Atmosphere Packaged Sliced Ham

Abstract

Two commercially available organic acid salts, potassium lactate (PURASAL HiPure P) and a potassium lactate-sodium diacetate blend (PURASAL Opti.Form PD 4), were assessed as potential inhibitors of Listeria monocytogenes growth in modified atmosphere packaged (MAP) sliced ham in challenge studies. The influence of the initial inoculation level of L. monocytogenes (10 1 or 10 3 CPU g-I) and storage temperature (4 or g0C) was also examined. The addition of either organic acid salt to MAP sliced ham strongly inhibited the growth of L. monocytogenes during the normal shelf life of the product under ideal refrigeration conditions (4°C) and even under abusive temperature conditions (i.e., g0C). During the challenge studies and in the absence of either organic acid salt, L. monocytogenes numbers increased by l,OOO-fold after 20 days at goC and IO-fold after 42 days at 4°C. Both organic acid salt treatments were found to be listeriostatic rather than listericidal. The addition of either organic acid salt to the MAP ham also reduced the growth of indigenous microflora, i.e., aerobic microflora and lactic acid bacteria. The influence of these compounds on the risk of listeriosis in relation to product shelf life is discussed.Unlike most foodbome pathogens, Listeria monocyto genes can grow, albeit slowly, at refrigeration temperatures, in the presence of >5% salt, and in the absence of oxygen (37). Processed meats, including ham and pate, are often packaged under vacuum or modified atmospheres and stored under refrigeration to extend their shelf life, typically being 6 to 8 weeks or more. Although initial contamination with L. monocytogenes, when present, is usually low, i.e., <10 CPU g-l (15, 28), its potential for growth in ready to-eat meats that are eaten without further cooking prior to consumption is, prima facie, considerable. Moreover, it is well documented that L. monocytogenes can grow in many such products during refrigerated storage, and such foods have caused, or been strongly implicated in, outbreaks of foodbome listeriosis that have resulted in fatalities (6-8, 23, 25).L. monocytogenes present on raw ingredients can be killed reliably by the heat treatments routinely applied dur ing smallgoods processing. During slicing and packaging after processing, however, recontamination can occur (16,18,24,30,39). During the past decade, the food industry has implemented hygiene practices and technologies that have greatly reduced the prevalence of L. monocytogenes on ready-to-eat foods (20,28). Nevertheless, the ecology of the organism, particularly its ability to colonize food processing plants (38), still results in L. monocytogenes be ing detected, typically, in -1 to 5%, or more, of processed meat products (1, 5, 15, 20, 28, 41).One approach to minimize the risk of listeriosis is to

Validation of Food-Grade Salts of Organic Acids as Ingredients To Control Listeria monocytogenes on Pork Scrapple during Extended Refrigerated Storage

“…Various food grade chemicals are antagonistic toward L. monocytogenes in foods when used as sprays and/or dip or bath applications and/or when added as an ingredient (6,14,24,26,28,29,37,40). Perhaps the best example is addition of up to 4.8% sodium or potassium lactate (wt/wt), either alone or in combination with up to 0.25% sodium diacetate (wt/wt), to the formulation of red meat or poultry products (2).…”

Comparative Efficacy of Potassium Levulinate with and without Potassium Diacetate and Potassium Propionate versus Potassium Lactate and Sodium Diacetate for Control of Listeria monocytogenes on Commercially Prepared Uncured Turkey Breast

“…The efficacy of lactate-diacetate (8,9,18,21,23) or propionate-benzoate (11) blends as antilisterial ingredients in RTE meats has been well established; however, no information has been published on the effectiveness of diacetate in combination with propionate as an antimicro bial blend for RTE meats. In the present study, we evaluated whether propionate-diacetate would have a po tency similar to that of lactate-diacetate for control of L. monocytogenes in RTE meats.…”

“…The most effective strategy used by the food industry to suppress L. monocytogenes outgrowth in RTE meats may be the inclusion of food grade antimicrobials, such as lactate and diacetate, as ingredients in these meat formulations (1,2,8,9,14,23,25,26,31,38). In general, the efficacy of growth inhibitors for reducing the risk and occurrence of L. monocytogenes could be affected by meat type (i.e., poultry versus pork), intrinsic characteristics of the product (e.g., pH, water activity, moisture, or nitrite level), and concen tration of the antimicrobial and/or its dissociation constant (i.e., pKa) (5,11,30).…”

Using a quantitative risk assessment to mitigate risk of Listeria monocytogenes in ready-to-eat meats in Australia

“…Accordingly, the accuracy of those assumptions should also be rigorously assessed to increase confidence in the predicted benefits of the alternative mitigation strategies considered, and is the basis of ongoing studies both in Australia (e.g. Mellefont and Ross, 2007) and internationally (e.g. Drosinos, Mataragas, Kampani, Kritikos and Metaxopoulos, 2006;Mejlholm and Dalgaard, 2007;Lianou et al, 2007) in ready-to-eat meats and analogous products.…”