Degree Type

Dissertation

Date of Award

2003

Degree Name

Doctor of Philosophy

Department

Animal Science

First Advisor

Joseph G. Sebranek

Abstract

Frankfurters, in 1-link, 5-link and 10-link packages, were surface-inoculated with a 5-strain mixture of Listeria monocytogenes (3.40 or 5.20 log CFU/g) after treatment with 3,000 or 6,000 AU pediocin (in ALTA(TM) 2341) per link (Pdn-3000 or Pdn-6000). The frankfurters were vacuum-packaged, after which the packages were heated in hot water at 71°C, 81°C or 96°C for 30, 60 or 120 s or irradiated at 1.2 or 2.3 (single-link or 5-link packages), and 1.4 or 3.5 kGy (10-link packages). L. monocytogenes was enumerated following the treatments. Selected treatments were subsequently evaluated during storage at 4°C, 10°C and 25°C for up to 12 weeks.;L. monocytogenes on frankfurters was reduced by pediocin alone, by pediocin combined with post-packaging thermal pasteurization (PPTP) or by irradiation pasteurization (PPIP) for all package types. To achieve a 50% reduction or more of initial inoculation numbers, the following treatments were necessary: Pdn-6000 alone, Pdn-6000 plus PPTP (≥81°C, ≥60 s), Pdn-3000 and PPIP (≥1.2 kGy), or PPIP (≥2.3 kGy) alone. Frankfurters treated with Pdn-6000 alone inhibited the growth of L. monocytogenes at 4°C for 12 weeks. Significant antilisterial, and even listericidal, effects for the combinations of Pdn-6000 and PPTP (96°C, ≥60 s) or PPIP (≥2.3 kGy) were observed. PPTP and PPIP treatments significantly (P < 0.05) enhanced the antilisterial effects of pediocin. There was a significant (P < 0.05) synergistic effect between pediocin and irradiation that was not observed for pediocin and thermal treatments.;Use of pediocin and other barriers (PPTP or PPIP) are effective means to control the growth of L. monocytogenes during storage at refrigeration temperatures. These treatments had greater antilisterial effects during storage at 4°C than 10°C and 25°C thus temperature remains a critical point for control of this pathogen. Smaller package types (≤5 links per packages) resulted in greater antilisterial effectiveness for PPTP treatments. While dipping or spraying are effective methods for surface treatment of frankfurters with antimicrobials, other methods such as coated casings or co-extrusion systems are much easier to use. Further work with these systems to increase the microbial impact of the antimicrobials is recommended.

DOI

https://doi.org/10.31274/rtd-180813-11157

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu

Copyright Owner

Chih-Ming Chen

Language

en

Proquest ID

AAI3085893

File Format

application/pdf

File Size

123 pages

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