Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science

First Advisor

Dong U. Ahn


This dissertation investigated the effect of irradiation and antimicrobials on the quality and survival of L. monocytogenes, a significant safety concern, in RTE turkey meat products. Results showed that dietary vitamin E was effective in reducing the number of L. monocytogenes carried by live turkeys, a source of L. monocytogenes contamination in RTE products. Irradiation was very effective in eliminating L. monocytogenes in both turkey breast rolls and hams. However, irradiation also caused quality changes. A dose of 2.0 kGy irradiation produced significant off-odor, mainly sulfur-related odor/flavor, in vacuum-packaged RTE turkey ham and rolls. Thus, only low dose irradiation is recommended. However, low-dose irradiation allowed some L. monocytogenes to survive during irradiation. Antimicrobial agents were formulated into RTE turkey rolls and hams as an additional hurdle to suppress the growth of L. monocytogenes that survived low-dose irradiation. Antimicrobials, including 0.1% potassium benzoate (PB), 2% sodium lactate (SL), and 0.1% sodium diacetate (SDA) were used singly or in combinations to assess their effectiveness in inhibiting the growth of L. monocytogenes in RTE meat products following low-dose irradiation. Results showed that for RTE turkey meats formulated with 0.1% PB + 2% SL or 2% SL + 0.1% SDA, 1.0 kGy irradiation was effective in suppressing the growth of L. monocytogenes for about six weeks at 4°C, and 2.0 kGy irradiation was listeriostatic during a 42-day refrigerated storage period. For RTE turkey meat formulated with three antimicrobials in combination, 0.1% PB + 2% SL + 0.1% SDA, 1.0 kGy irradiation was listeriostatic. Including 2% SL in formulation, however, slightly affected the texture and color values of turkey breast rolls, and the addition of PB in RTE turkey meats produced a high amount of benzene after irradiation. Considering their antilistenal activity and their effects on quality, including 2% SL plus 0.1% SDA in formulation in combination with 1.0- or 2.0 kGy-irradiation was a promising technology to ensure the safety of RTE turkey ham and breast rolls from L. monocytogenes.



Digital Repository @ Iowa State University,

Copyright Owner

Meijun Zhu



Proquest ID


File Format


File Size

204 pages