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During storage.

In meat and fish technology, sodium lactate (E325) is one of the most useful “hurdle ingredients” for extending shelf life and belongs to the group of inhibitors of pathogenic microorganism growth in food. Its effectiveness is especially clear in finished products where hygiene of the raw material and production has been taken care of, limiting contamination at an early stage of product formation.

1. HOW DOES SODIUM LACTATE WORK?

Sodium lactate works through several mechanisms at once:

• it lowers water activity,
• it increases the osmotic pressure of the cell’s environment, forcing the bacterium to spend more energy maintaining homeostasis,
• it disrupts microbial metabolism, the lactate ion interacts with, among other things, membrane transport and energy metabolism,
• it extends the microbial lag phase — in practice this is one of the most important effects: the bacterial count does not necessarily drop sharply, but their growth begins much later,
• it lowers the maximum growth rate, which is why lactate is especially valuable where you need to “buy time” during chilled storage.

This is well illustrated by data for cooked ham: at 4°C, a 1% lactate addition reduced the growth rate of L. monocytogenes by around 35%, and 2% by around 60%, compared to the control sample. At a 3% dose, growth of the tested pathogens was inhibited much more strongly.

2. SODIUM LACTATE 60% LIQUID OR SODIUM LACTATE 98% POWDER.

Advantages of sodium lactate 60% liquid:

• very easy distribution in brine,
• fast dissolution,
• easy dosing at the brine station,
• ideal for injection,
• easy to massage,
• no dusting,
• very even distribution.

Disadvantages of sodium lactate 60% liquid:

• contributes around 40% water,
• increases the amount of brine,
• at high doses can limit the possibility of injecting other ingredients,
• higher transport mass and higher logistics costs,

Advantages of sodium lactate 98% (NATRILAC-98) powder:

• very high concentration,
• practically no added water,
• easier to use in dry blends,
• favourable in products with a limited amount of available brine,
• attractive for dry marinades, fillings and functional blends.

Disadvantages of sodium lactate 98% (NATRILAC-98) powder:

• strong hygroscopicity,
• possible caking,
• requires very thorough dissolution,
• direct addition to the filling can locally create a high concentration,
• homogenisation must be controlled more precisely.

3. DOSING SODIUM LACTATE 60% LIQUID VS SODIUM LACTATE 98% POWDER.

Liquid form dose 2.0–2.5%:

• delayed growth for Listeria,
• limitation of LAB,
• limitation of Enterobacteriaceae,
• extension of the time needed to reach the TVC/APC threshold count.

Liquid form dose 3.0%:

Strong inhibitory effect, especially attractive for:

• RTE cured meats,
• hams,
• chicken breast,
• vacuum products,
• MAP products,
• some fish products.

Above this level, the limiting factor increasingly becomes:

• saltiness (be sure to account for reduced sodium content elsewhere in the recipe),
• the characteristic taste,
• total sodium content,
• recipe economics.

In this case, dosing the powder form at a 4–5 times lower dose will provide an equivalent microbiological stabilisation effectiveness compared to the liquid version.

4. WHICH MICROORGANISMS DOES SODIUM LACTATE ACT AGAINST?

a/ Listeria monocytogenes.

This is key. Sodium lactate is especially useful in RTE products, because L. monocytogenes can multiply under refrigeration. EFSA notes that RTE cooked meats can allow Listeria growth, especially at the high aw and pH typical of cooked meat products.

Sodium lactate should not be treated as a method of killing Listeria – it is primarily a bacteriostatic agent, and the key parameter is:

Δ log CFU/g over the entire shelf life.

b/ Enterobacteriaceae.

Generally good effect.

In raw products, its use can significantly delay the onset of:

• off-odour,
• slime,
• gas formation,
• colour changes.

c/ Pseudomonas.

The effect is most visible where Pseudomonas can grow, especially in aerobic products. However, in MAP/vacuum the microflora composition changes and LAB become increasingly significant.

d/ LAB.

Sodium lactate can delay the growth of lactic acid bacteria.

e/ Salmonella / E. Coli.

Lactate can limit their growth, but remember that sodium lactate will not compensate for a broken cold chain.

5. PREDICTED SHELF LIFE FOR MEAT.

The table below should not be treated as a declared shelf life. These are indicative technological values, assuming good production hygiene and an actual product temperature of 0–4°C. Dose: 2–3% sodium lactate 60%.

Production conditions vary slightly between plants, and each plant receives different raw material at different times, so it is worth running your own tests.

Two products with the same recipe can have completely different shelf lives at the same starting microbial load:

10² CFU/g vs 10⁴ CFU/g.

6. THE POLISH CONTRIBUTION TO THE MICROBIOLOGICAL STABILISATION OF FOOD PRODUCTS USING SODIUM LACTATE.

In the second half of the 1990s, the Polish company PPF AKWAWIT in Leszno Wlkp. was the first in the country to begin its own production of sodium lactate and undertook a series of research and practical work on an industrial scale to demonstrate the potential of this lactic acid salt in extending the shelf life of meat products.

a/ Tests: industrial scale, 1998 / Publication:

Waldemar Uchman, Jan Zabielski, Commercial Scale Application of Sodium Lactate for Shelf Life Extension of Vacuum Packed Ham Type Pork Products, 44th International Congress of Meat Science and Technology — ICoMST, 1998.

The Institute of Meat Technology at the Agricultural University in Poznań carried out industrial-scale tests using SODIUM LACTATE 60% L(+) produced by PPF AKWAWIT.

Two high-yield pork products were tested:

• pasteurised pork ham,
• coarse-ground cooked ham sausage.

Technological yield was approximately:

140% — ham

160% — ham sausage.

This is particularly interesting, as these were products with a high amount of added brine, i.e. microbiologically more challenging than traditional low-yield cured meats.

Doses of AKWAWIT sodium lactate 60%.

Levels tested corresponded to approximately:

• 0% (zero sample),
• 0.6% active sodium lactate,
• 1.5% active sodium lactate.

Converted to the 60% commercial product, this meant a sodium lactate 60% share of

In practice, this means:

1 kg active lactate = approx. 1.67 kg of the 60% solution.

Storage conditions.

24 hours after production, the products were:

• sliced,
• vacuum packed,
• stored at 2–4°C,
• for 40 days.

Analyses were carried out at roughly 10-day intervals.

The main parameters tested were:

• total plate count — TPC,
• microflora growth dynamics,
• sensory characteristics: appearance, colour and taste.

The microbiological results were very good. The authors calculated a coefficient describing the dynamics of bacterial growth. The addition of sodium lactate reduced TPC growth dynamics by approximately:

1.6–5.6 times, depending on the product tested.

Even more interesting was the time needed for the total bacterial count to increase by 1 log, i.e. tenfold.

• ham without sodium lactate: approximately 17 days,
• ham with sodium lactate: approximately 37–42 days,
• ham sausage without sodium lactate: approximately 17 days,
• ham sausage with sodium lactate: up to 52 days.

These studies confirmed that sodium lactate extends the logarithmic growth phase over time and clearly slows down the dynamics of microflora growth.

b/ Another study/test – poultry sausage.

Renata Cegielska-Radziejewska, Jan Pikul, Sodium Lactate Addition on the Quality and Shelf Life of Refrigerated Sliced Poultry Sausage Packaged in Air or Nitrogen Atmosphere,
Journal of Food Protection, 2004, Vol. 67, No. 3, 601–606.

The authors used a natural liquid 60% sodium lactate preparation obtained from PPF Akwawit, Leszno.

Three application levels were tested:

• 0% (blank sample),
• 1% sodium lactate,
• 2% sodium lactate.

The sausage was heated to a core temperature of approximately 72°C, cooled, sliced and packed in various atmospheres.

Results:

Lactate:

• limited the growth of psychrotrophic bacteria,
• limited LAB,
• slowed the formation of malondialdehyde — i.e. reduced lipid oxidation,
• improved sensory shelf life.

1% sodium lactate 60% → approximately a 3-fold extension of shelf life

2% sodium lactate → approximately a 4-fold extension of shelf life

The best result was obtained for: 2% lactate + nitrogen atmosphere, with a shelf life of:

35 days

which the authors described as approximately a 7-fold extension of shelf life compared to the control sample.

As we can see, innovation was also not lacking in our country during a period of turbulent economic change, and in this case it confirmed the effectiveness of SODIUM LACTATE 60% in food stabilisation.

Unfortunately, at the end of the 1990s, colliding with a financially strong European market, without understanding or support from the Polish state, hit the PPF AKWAWIT company hard, which was unable, on its own, to compete and withstand the competition — ultimately leading to the closure of the lactic acid and derivatives plant within less than 10 years of undertaking this ambitious project.