Inhibition of Listeria monocytogenes by sodium diacetate and sodium lactate on wieners and cooked bratwurst

Abstract

The inhibition of Listeria monocytogenes by sodium lactate and sodium diacetate was evaluated for wieners containing pork, turkey, and beef and for cooked bratwurst containing beef and pork. Both products were supplied by commercial manufacturers. Treated products were surface-inoculated with 105 CFU of L. monocytogenes per package and vacuum-packed in gas-impermeable pouches. Wieners were stored for 60 days at 4.5°C, and bratwurst were stored for 84 days at 3 and 7°C. A surface treatment that consisted of dipping wieners into solutions containing ≤6% lactate and ≤3% diacetate for 5 s did not delay pathogen growth compared with that for untreated wieners. In additional trials, the antilisterial activity of lactate and diacetate in wiener and bratwurst formulations was evaluated. Lactate levels ranged from 1.32 to 3.4%, and diacetate was evaluated at 0.1 and 0.25%. The growth of L. monocytogenes was delayed for 4 and 12 weeks at 7 and 3°C, respectively, on uncured, unsmoked bratwurst formulated with 3.4% lactate/0.1% diacetate, compared with 1 and 2 weeks, respectively, for the formulation containing 2% lactate. L. monocytogenes grew by ≥1 log unit after 4 weeks' storage at 3 or 7°C on cured, smoked bratwurst without lactate or diacetate, but growth was inhibited for 12 weeks on cured, smoked bratwurst formulated with 3.4% lactate and 0.1% diacetate. Sodium lactate levels of ≥3% and combinations of ≥1% lactate plus ≥0.1% diacetate prevented listerial growth on wieners stored for 60 days at 4.5°C. These results indicate that dipping wieners in lactate-diacetate solutions is not an efficient way to apply these antimicrobial agents to wieners. However, the inclusion of combinations of sodium lactate and sodium diacetate in wiener or bratwurst formulations inhibits the growth of L. monocytogenes at ≤7°C, and an additional margin of safety was observed for products that are cured and smoked.