THE EFFECTS OF DIACETATE WITH NITRITE, LACTATE, OR PEDIOCIN ON THE VIABILITY OF LISTERIA-MONOCYTOGENES IN TURKEY SLURRIES

The antilisterial effects of sodium diacetate (0.1, 0.3 and 0.5%) alone or in combination with sodium nitrite (30 ppm), sodium lactate (2.5%) or pediocin (5000 arbitrary units/ml) were evaluated in slurries (25% meat in sterile deionized H2O) prepared from vacuum-packaged, ready-to-eat turkey breast meat and challenged with Listeria monocytogenes. In the absence of food additives, counts of L. monocytogenes increased from 4.5 log10 cfu/ml to ca. 8 log10 cfu/ml within 1 day at 25-degrees-C and within 14 days at 4-degrees-C. Similarly, the pathogen grew to ca. 8 log10 cfu/ml within 1 d at 25-degrees-C and within 28 days at 4-degrees-C in slurries containing nitrite or lactate. In the presence of pediocin, after an initial decrease of 0.9 log10 cfu/ml, numbers of the pathogen reached ca. 8 log10 cfu/ml within 5 days at 25-degrees-C and within 28 days at 4-degrees-C. However, 0.3 and 0.5% diacetate in turkey slurries were listericidal at 4 and 25-degrees-C, respectively. In the presence of nitrite with diacetate, there was no appreciable difference in growth of L. monocytogenes compared with diacetate alone. Antilisterial activity was potentiated in treatments containing lactate with 0.3% diacetate at 25-degrees-C and lactate with 0.1% diacetate at 4-degrees-C, compared to similar treatments containing diacetate or lactate alone. A listericidal effect (ca. 7 log10) cfu/ml difference compared to slurries without additives) was observed in treatments containing pediocin with 0.5% diacetate at 25-degrees-C and pediocin with 0.3% diacetate at 4-degrees-C. The pH of slurries containing 0.3 or 0.5% diacetate was 5.5 and 5.2, respectively, whereas nitrite (pH 6.2), lactate (pH 6.3) or pediocin (pH 6.2) in slurries had a negligible effect on pH compared to the control (pH 6.2). The increased antilisterial activity in slurries with diacetate in combination with other additives was due to synergistic effects and not just pH. Thus, sodium diacetate alone can be used to delay growth of L. monocytogenes in turkey, and an additional level of safety can be achieved using diacetate in combination with sodium lactate or pediocin.