Author

Shweta Kumari

Advisor

Coggins, C. Patti

Committee Member

Martin, M. James

Committee Member

Williams, Byron J.

Committee Member

Bailey, Hartford, R.

Date of Degree

8-1-2008

Document Type

Graduate Thesis - Open Access

Abstract

Post process application of antimicrobials is one method to control recontamination of Listeria monocytogenes on cooked RTE meat products. This study evaluated the antilisterial effect of externally applied solutions of nisin, buffered solution of sodium citrate supplemented with sodium diacetate (SCSD) and a combined solution of the two antimicrobials on commercial beef frankfurters formulated without antimicrobials. Autoclaved frankfurters were inoculated (104 -105 CFU/g), dipped (5 min, 25 ± 2°C) in treatments consisting of 2000; 4000;or 6000 IU/ml nisin, and buffered solutions of 2.5; 3.0; or 3.5% SCSD (Study I), and 6000 IU/ml nisin followed by 3.5% SCSD, or 3.5% SCSD followed by 6000 IU/ml nisin, or a combined solution containing both 6000 IU/ml nisin and 3.5% SCSD(Study II). Treated hot dogs were vacuum packaged and stored at 4 and 10°C. L. monocytogenes counts were determined on Modified Oxford Agar on 0, 14, 28, and 42 days at 4°C and 0, 4, 8, 12, 16, and 20 days at 10°C. Nisin (6000 IU/ml) initially reduced L. monocytogenes population by 2.1 and 2.5 logs (at 4 and 10°C, respectively on day 0), buffered SCSD (3.5%) by 1.1 and 0.2 logs (at 4 and 10°C, respectively on day 0) and the combined solution by 1.7 and 2.0 logs (at 4 and 10°C, respectively on day 0). The combined solution was the most effective treatment compared to nisin and buffered SCSD, used in sequence or alone, since it inhibited the growth of L. monocytogenes during 28 days at 4°C. The buffered SCSD was effective against L. monocytogenes at 4°C but not at 10°C. Further research is needed to investigate the effectiveness of buffered SCSD with other antimicrobials. The results of this study may be useful for further research on combinations of antimicrobials.

URI

https://hdl.handle.net/11668/15323

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