Purpose: Validate the efficacy of acetic acid-based antimicrobials as ingredients to control L. monocytogenes inoculated onto commercially-produced frankfurters.
Methods: Pork-beef-water frankfurters were formulated by a cooperating processor with or without 0.9%, 1.15%, or 1.40% of buffered vinegar [BV; e(Lm)inate V], a blend of buffered vinegar and potassium lactate [VL; e(Lm)inate VL], or a blend of potassium lactate, potassium acetate, and sodium diacetate [LAD; e(Lm)inate LAD], or 2.37% of a blend of potassium lactate and sodium diacetate [Klac; Ultralac KL 564]. Frankfurters were surface inoculated with 2 ml of a five-strain mixture of L. monocytogenes to achieve a target level of ca. 4.3 log CFU/package. The packages were then vacuum-sealed and stored at 4°C for up to 120 days.
Results: In the absence of any antimicrobials, pathogen numbers increased by ca. 6.0 log CFU/package after 120 days at 4°C. When antimicrobials were included in the formulation, the higher the concentrations used, the greater the observed inhibition of L. monocytogenes. When frankfurters were formulated with 0.9% of BV, VL, or LAD, pathogen numbers increased by ca. 1.0 to 4.0 log CFU/package over 120 days at 4°C, whereas when formulated with 1.15% of BV, VL, or LAD pathogen numbers remained relatively unchanged. In contrast, pathogen numbers decreased by ca. 0.7 to 1.2 log CFU/package when frankfurters were formulated with 1.4% of BV, VL, or LAD or 2.37% of Klac.
Significance: Inclusion of 1.15 or 1.4% of BV, VL, or LAD as ingredients in frankfurters was equally effective as 2.37% Klac at suppressing outgrowth of L. monocytogenes during extended refrigerated storage.