Purpose: Determine viability of Lm on casing-cooked ham, formulated or surface treated with food grade antimicrobials, during refrigerated and/or frozen storage (i.e., sleeping at -2.2°C).
Methods: Hams were commercially prepared +/- potassium lactate and sodium diacetate (PM; 1.6%), buffered vinegar (BV; 2.2%), buffered vinegar and potassium lactate (VL; 1.7%), or potassium lactate, potassium acetate, and sodium diacetate (LAD; 1.7%), as well as +/- surface treated with lauric arginate ester (LAE; 44 ppm). In Phase I, hams (ca. 3.5 kg each) were sliced and inoculated (ca. 4.3 log Lm/slice), treated with LAE, and stored at either 4°C for 120 days or at -2.2°C for 90 days and then at 4°C for 120 days. In Phase II, inoculated/treated whole hams (ca. 1.0 kg each) were stored at -2.2°C for up to 6 months.
Results: In Phase I, without antimicrobials Lm increased by > 5.0 log CFU/slice within 90 days at 4°C; however, Lm increased slightly for hams formulated with PM and decreased by ca. 1.2 log CFU/slice when formulated with the other antimicrobials. For slices held/slept at -2.2°C and then stored at 4°C but not treated with LAE, Lm increased ca. 5.0 log CFU/slice for controls, whereas when formulated with antimicrobials, Lm decreased by ca. 1.5 log CFU/slice. For product treated with LAE, Lm increased ca. 4.5 log CFU/slice for controls, whereas when formulated with antimicrobials, Lm decreased by ca. 0.9 log CFU/slice for PM and by ca. 1.5 to 2.0 log CFU/slice for BV, LAD, and VL. In Phase II, Lm decreased by ca. 4.0 to 5.0 log CFU/ham when held/slept at -2.2°C.
Significance: Sleeping hams at -2.2°C was listericidal and inclusion of antimicrobials suppressed outgrowth of Lm during extended storage.