Inhibition of Listeria monocytogenes in Deli-style Turkey Breast Using Alternate Curing Systems and Clean Label Antimicrobials

Introduction: Fermentation-derived nitrite (NO₂) from vegetable sources is increasingly used as a “clean label” alternative to conventional NaNO₂. While some studies suggested that processed meats produced in this manner had lower inhibitory properties than conventionally cured meats, the differences are likely attributed to NO₂ concentration rather than the source.

Purpose: Compare the antilisterial properties of traditional and “clean label” fermentation-derived curing approaches when combined with antimicrobials in deli-style turkey.

Methods: Listeria monocytogenes inhibition by NO₂ from synthetic and natural sources was validated in deli-style turkey (73-74% moisture, 1.8% salt, pH 6.4). Products were prepared with 0, 80 or 120 ppm NaNO₂ equivalent using synthetic NaNO₂ or cultured celery powder; treatments with 0 or 80 ppm nitrite were further supplemented with 3.8% lactate-diacetate (LD) or 1% commercial fermentate (DF). Sliced cooked products were surface inoculated with 3 log CFU/g of L. monocytogenes, vacuum packaged, stored at 4°C and triplicate samples assayed through 12 weeks; study was replicated twice.

Results: Results revealed an average 2.4 log L. monocytogenes increase at 3 weeks in the control without antimicrobials, 1.3 log increase at 4 weeks for both 80 ppm NO₂ treatments and a 1.5 log increase at 6 weeks for the 120 ppm NO₂ treatments; there was no significant difference in growth inhibition between the two NO₂ sources when equivalent concentrations were added. Uncured turkey with 3.8% LD or 1% DF both delayed growth until 6 weeks, whereas supplementing LD or DF with 80 ppm nitrite from either source delayed listerial growth through 12 weeks.

Significance: This study confirmed that the concentration of NO₂, rather than source, is the primary factor in enhancing the safety of ready-to-eat meats. A clean label solution consisting of a fermentation-derived antimicrobial in combination with 80 ppm naturally-derived NO₂ was shown to inhibit L. monocytogenes through 12 weeks storage at 4°C as well as conventional-NO₂ versions.