The use of antimicrobial ingredients in combination with irradiation is an effective antilisterial intervention strategy for ready-to-eat meat products. Microbial safety was evaluated for frankfurters formulated with 0% or 3% added potassium lactate/sodium diacetate solution and inoculated with Listeria monocytogenes before or after treatment with irradiation (0, 1.8, or 2.6 kGy). Frankfurters were stored aerobically or vacuum packaged and L. monocytogenes counts and APCs were determined while refrigerated. The incorporation of lactate/diacetate with or without irradiation had a strong listeriostatic effect for aerobically stored frankfurters. Outgrowth was suppressed and counts were not different from initial counts (5.2 log CFU/frank compared with 5.0 log CFU/frank); however, those without the additive increased steadily (5.4 to 9.3 log CFU/frank). Irradiation treatments alone had higher L. monocytogenes counts after 3 wk. For vacuum-packaged frankfurters, both the addition of lactate/diacetate and irradiation were effective at controlling growth after 8 wk. Large and incremental reductions in total counts were seen for irradiation treatments. Initial counts were reduced by 3 log CFU with the application of 1.8 kGy while 2.6 kGy decreased counts over 5 log CFU. These reductions were maintained throughout storage for lactate/diacetate-treated frankfurters. By 8 wk, L. monocytogenes counts on 1.8 and 2.6 kGy irradiated frankfurters without lactate/diacetate increased to 7.43 and 6.13 log CFU, respectively. Overall, lactate/diacetate retarded the outgrowth of L. monocytogenes on frankfurters throughout aerobic storage and the combination of irradiation and 3% lactate/diacetate reduced and retarded growth of L. monocytogenes, especially during the last 2 wk of vacuum-packaged storage.

Quality attributes were evaluated for irradiated (0, 1.8, or 2.6 kGy) frankfurters formulated with 0% or 3% potassium lactate/sodium diacetate solution and stored aerobically or vacuum packaged at 4 degrees C for 4 or 8 wk, respectively. Quality analyses included descriptive sensory panel, pH, L*a*b* color values, and TBARS determination. Aroma and flavor quality were retained for aerobically stored frankfurters with lactate/diacetate throughout shelf-life. Meaty/brothy complex aroma and flavor, smoke aroma and aftertaste, spice aroma and flavor, astringency, sourness, bitterness, springiness, cohesiveness, and juiciness attributes were lower for aerobically stored frankfurters formulated without lactate/diacetate compared to those with lactate/diacetate toward the end of storage. Sensory color and other quality attributes were minimally influenced by either treatment. Addition of lactate/diacetate and irradiation were also effective shelf-life extenders for vacuum-packaged frankfurters. There were fewer influences on sensory characteristics for vacuum-packaged frankfurters compared to those that were aerobically packaged. However, small yet significant differences were detected by sensory panelists for some aroma and flavor attributes, which remained consistent between treatments throughout storage. Sensory and instrumental color scores varied slightly, but were fairly consistent throughout vacuum-packaged storage. Overall, lactate/diacetate retarded deterioration of frankfurters throughout aerobic storage and helped maintain quality with or without irradiation for vacuum-packaged frankfurters.