Author
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Bhaduri, Saumya |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 1/31/2006 Publication Date: 8/13/2006 Citation: Bhaduri, S. 2006. Thermal inactivation and injury of freeze-stressed campylobacter jejuni in ground chicken. {Abstract} International Association of Food Protection. PB2-40:126-127. Interpretive Summary: Technical Abstract: Although foods of animal origin, mainly poultry and poultry products, are associated with Campylobacter jejuni infection, relatively little is known on the ability of this organism to adapt to environmental conditions, such as cold stress and thermal processing. Therefore, inactivation and injury of C. jejuni by heating in ground boneless chicken breasts with and without prior freeze-stress was investigated. Ten-gram portions of ground chicken were irradiated and artificially contaminated with approximately 10^8 CFU/g of a cocktail of three strains of C. jejuni. A set of samples stored at -20 degrees C for 14 d and an otherwise similar set of samples that was not frozen were both heated to 50, 60, and 74 degrees C. Frozen storage at -20 degrees C for 14 d produced a reduction of viable cell counts to 10^5 CFU/g. At various time intervals, samples were pummeled in a Stomacher Lab Blender for 2 min and serial dilutions were surface plated onto Mueller Hinton agar (MHA) to enumerate the surviving cells, as well as plated onto MHA with 3% NaCl (MHAS) to detect the possible occurrence of thermally-injured cells. The MHA and MHAS plates were incubated for 48 h at 42 degrees C in sealed jars under microaerophilic conditions generated by CamyPak Plus gas generators. Based on the average of duplicate experiments the corresponding D-values were 59.3 min, 1.89 min, and 4.28 sec in samples without prior freeze-stress and 36.25 min, 1.80 min, and 3.94 sec in samples subjected to freeze-stress and then heated at 50, 60, and 74 degrees C, respectively. In general, the recovery of cells on MHAS was lower than on MHA for samples with and without prior freeze-stress that were subsequently heated at 50, 60, and 74 degrees C. This study indicates that freeze-stress at -20 degrees C for 14 d of C. jejuni in ground chicken does not appreciably affect the thermal inactivation of this pathogen (p>0.05) and that heating at 74 degrees C for 30 sec ensured inactivation of C. jejuni in ground chicken. |
