Effect of sodium lactate, sodium nitrite, pH and temperature on growth of listeria monocytogenes

摘要

Standard Bologna-type sausages were manufactured using six different formulations: (a) standard with 60ppm nitrite, (b) standard with 150ppm nitrite, (c) standard with 60ppm nitrite and 2 percent lactate, (d) standard with 150ppm nitrite and 2 percent lactate, (e) standard with 60ppm nitrite and 3 percent lactate, (f) standard with 150ppm nitrite and 3 percent lactate. PH was kept at 6,3 for all formulations. The sliced sausages were inoculated with a strain of Listeria monocytogenes (L.m.) serotype 4 (700 cfu/g). The samples were vacuum-packaged and stored at 4 deg C and 8 deg C for 35 days. Rapid growth of L.m. was observed in formulations a and b at 4 deg C and 8 deg C. In formulation c after 35 days of storage the level of L.m. was equal to the inoculation level at 4 deg C. However at 8 deg C growth started after 2 weeks storage and reached a level of 1 million L.m. per gram after 35 days. In formulation d, e and f no growth was observed after 35 days either at 4 deg C or 8 deg C. However, when using 3 percent lactate, off-flavours were registered by a trained taste panel. It can be concluded that it is possible to prevent growth of L.m. in chilled meat products at pH 6.3 for 35 days using suitable amounts of sodium lactate and sodium nitrite. However the concentration of lactate should not exceed 2 percent for quality reasons.