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|Title:||Effects of pasteurization and refrigerated storage on the quality of precooked beef|
|Author(s):||Cooksey, D. Kay|
|Doctoral Committee Chair(s):||Klein, Barbara P.|
|Department / Program:||Human and Community Development|
|Discipline:||Human and Community Development|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Food Science and Technology|
|Abstract:||The objectives of the research were to develop a process for precooking and pasteurization of vacuum packaged beef loin steaks and to examine its effectiveness for elimination of Clostridium perfringens and Listeria monocytogenes. Three common precooking methods were examined and no differences were observed between oven, waterbath and smokehouse cooling procedures (P $>$ 0.05) for thiamin retention and meat composition. A pasteurization process was established for steaks obtained from waterbath precooked roasts. Steaks were pasteurized using three different waterbath temperatures. Texture profiles of precooked steaks were similar to nonpasteurized steaks. Steaks processed in 85$\sp\circ$C water had a heating profile most conducive to microbial destruction.
Precooked beef loin chunks were inoculated with either vegetative cells or spores of Clostridium perfringens and an uninoculated group served as the control. All chunks were vacuum packaged after inoculation and placed in storage (4$\sp\circ$C) for up to 85 days. Precooked chunks were pasteurized in 85$\sp\circ$C water prior to storage. Pasteurization reduced C. perfringens by 5 orders of magnitude in the broth and 1.5 orders of magnitude on the surface. Without pasteurization, vegetative cells of C. perfringens survived well in the meat broth for 28 days and spores remained at a constant level in the broth until 65 days of storage. Presence of C. perfringens on the surface of nonpasteurized chunks was minimal. After 28 days, microflora grew to high levels in nonpasteurized chunks.
Precooked beef loin chunks were inoculated separately with three strains of Listeria monocytogenes (Scott A, 101M, and 103M). Uninoculated chunks served as controls. All chunks were processed and stored as described above. Pasteurization completely eliminated microflora and all three strains of L. monocytogenes on the surface and in the broth of the precooked beef chunks for 85 days of refrigerated storage. L. monocytogenes were recovered from inoculated beef loin chunks using enrichment. Uninoculated beef chunks were positive for Listeria spp. in nonpasteurized chunks without enrichment and were primarily L. welshimeri. Without pasteurization, microflora reached high levels within 14 days of storage. All three strains of L. monocytogenes survived in nonpasteurized chunks, but did not increase significantly during 85 days of storage.
Overall, pasteurization was effective in reducing microbial load in precooked vacuum packaged beef. This technique could be used to extend the shelf-life of precooked meats and reduce the risk of foodborne illness when used in combination with appropriate quality controls.
|Rights Information:||Copyright 1992 Cooksey, D. Kay|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9236435|
This item appears in the following Collection(s)
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois
Dissertations and Theses - Human and Community Development