The trend for sodium reduction is clear. Food companies want to comply with the World Health Organization’s (WHO) advice to reduce sodium content but often struggle with increased costs or flavor impact. Our white paper explains how the safety and shelf life of your meat product can be increased without any addition of sodium and at lower costs than your current way of preservation.
Basic treatments to keep processed meat products fresh are cold storage and packaging under a modified atmosphere (MAP). Despite creating a suboptimal environment for microbial growth, Listeria monocytogenes is still able to grow and to create danger for human health. In addition to this food safety issue, spoilage featured by slime formation and acidic smell and taste is another factor that makes food inedible. These spoilage characteristics are typical for bacteria in the class of Lactobacillales or lactic acid bacteria (LAB). These organisms are also able to grow in the created environment of low temperatures and limited oxygen. Acetates and di-acetates are well known for their inhibitive action against Listeria monocytogenes. Since Provian®K is an acetate/di-acetate composition, it is no surprise that Provian K shows outstanding results for Listeria inhibition in meat. Despite lactic acid bacteria are known for their tolerance to many antimicrobials, they show sensitivity to organic acids like acetic acid and propionic acid and so they are controlled by Provian® K. The explanation for this can be found in basic chemistry combined with microbiology: The fact that organic acids are antimicrobial effective in their undissociated form was already described by Eklund et al. in 19832. Therefore, the amount of undissociated acid in the environment is of importance for the antimicrobial efficacy of the organic acid salts. The standard dissociation curves of some organic acids (Acetic acid, Lactic acid, Caproic acid, and Propionic acid) below, show an increase of undissociated acid when the pH is decreased (see figure 1). The different pKa values result in a higher amount of undissociated acids available for Acetate and Propionate (see table in figure 1) than for Lactate.
Another factor that influences the efficacy of organic acids and its salts, is Log P, which indicates the lipophilicity. Since the membrane is composed of a (phospho) lipid bilayer we may assume that lipophilic compounds can cross this barrier with more ease than hydrophilic compounds 3. This may explain the lower Minimal Inhibitory Concentration (MIC) value for Caproic acid shown in table 1, compared to propionic which has the same pKa value (see table 1).
The final inhibitory effect is explained by the use of the proton pump of the microorganism (the proton motor force). To keep the internal pH stable, this pump will be used to pump out protons, causing energy depletion.
Table 1 partition coefficients of some organic acids for an
octanol / water system (logPoct),. experimentally verified
logPoct values (2). The second column gives logPoil values
calculated from logPoct using equation 2. The third column
gives values for –log of the acid dissociation constant, pKa
(2).The last column shows the efficacy of the acids against
L.plantarum in broth at pH 6 .
Being focused on LAB growth suppression, it is easy to overlook the upside of the growth of LAB in food products. Namely, these spoilage bacteria hinder pathogens like Listeria monocytogenes from growing in the same environment. Inhibition of LAB stimulates Listeria monocytogenes to grow and create a food safety issue.
The question could arise whether it is worth to suppress spoilage bacteria with the risk of potential danger. Various facts make more than one answer possible. One is the fact that extending shelf life has a direct impact on food waste which is in favor of global sustainability(6). Another is the fact that the extension of shelf life can save the food supplier substantial amounts of money(5). In order to extend the shelf life of meat products without compromising safety and health, Niacet developed Provian®K, which is an antimicrobial powder based on potassium acetate and potassium diacetate. This patented(7) free-flowing powder was developed using advanced technology based on spray drying and crystallization. The powder was developed to enhance ease in handling, shipping, storing and mixing, compared to liquids. The high efficacy means a low dosage rate in the application, which results in an environmentally friendly product due to eliminating the need to transport or store bulky liquid containers. The sodium-free composition makes Provian®K an excellent choice in sodium reduction programs and formulations.
In order to prove its efficacy in meat products, Provian®K was tested in Frankfurters as well as in turkey ham applications. The graphs below show the outstanding efficacy of Provian®K against Listeria monocytogenes compared to the commonly used lactic acid-based liquid product. Using Provian®K demonstrates a lower dosage, a reduction in costs, and fewer e-numbers (only one) to declare. The table below the two graphs reflects the number of weeks to reach 1 log (cfu/gram) of growth.
Another test was performed in uncured meat to show the efficacy of Provian®K against a cocktail containing various species of Lactic acid bacteria, e.g. Leuconostoc mesenteroides, Lactococcus lactis (see figure 3). The table below the graphs shows the shelf life for the different treatments and a control without any preservatives.
An extensive sensory evaluation(7) in deli-style turkey ham resulted in no significant differences in taste compared to the control without Provian® K. According to the results shown here, it may be concluded that Provian® K is a highly effective sodium-free meat preservative, even in uncured products. It increases product safety by controlling Listeria monocytogenes as well as helping to extend the shelf life by inhibiting the growth of a variety of lactic acid bacteria.
2. Eklund T. The antimicrobial effect of dissociated and undissociated sorbic acid at different pH levels. J Appl Bacteriol. 1983 Jun;54(3):383-9.
3. Sikkema, J.; J.A.M.de Bont; B.Poolman (1994) Interactions of cyclic hydrocarbons with biological membranes. J. Biol. Chem. 269: 8022 8028
4. LogP oct Syracuse Research Corporation website http://esc.syrres.com/fatepointer/search.asp, the SRC PhysProp Physical Properties database
5. Extending product life can cut food waste and save millions: Waste & Resources Action Programme (March 2015)
6. Retail Sector Wastes 200,000 Tonnes Of Food Every Year: Chartered Institution of Wastes Management (2015) –http://www.ciwm-journal.co.uk/archives/11727
7. Glass K., Golden M., Wanless B., Comparison of Antimicrobials on the Inhibition of Listeria monocytogenes on Cured RTE Meats. Internal Niacet Report performed by Food Research Institute, Wisconsin University, October 2, 2014. https://www.niacet.com/wpcontent/uploads/MaxGolden-Niacet_IAFP2015.pdf