Pretreatment effect on inactivation of Escherichia coli O157:H7 inoculated beef jerky

Changes in inoculated Escherichia coli O157:H7 populations were determined during drying (62.5 C, 10 h) of whole muscle beef jerky slices pretreated by: (1) immersing in boiling water (94 C, 15 s), then marinating (4 C, 24 h); (2) seasoning (4 C, 24 h), then immersing in a pickling brine (78 C, 90 s); (3) immersing in a vinegar/water (750/750mL) solution (57.5 C, 20 s), then marinating (4 C, 24 h); and (4) marinating (4 C, 24 h), then immersing in a vinegar/water (750/750mL) solution (57.5 C, 20 s). Samples were analysed (bacterial enumeration with selective and nonselective agar media, pH, and aw) following inoculation, each preparation step, and at 0, 4, 6, 8 and 10 h of drying. While all pre-drying treatments resulted in significant ðPo0:05Þ bacterial reductions, treatment 2 resulted in the greatest pre-drying reduction (3.1–4.1 log cfu/cm) and the highest overall reduction at 10 h drying (5.7–5.8 log cfu/cm). Total reductions for treatments 1, 3 and 4 after 10 h drying were 4.3–4.5, 4.9–5.2 and 4.7–4.8 log cfu/cm, respectively. Bacterial populations declined to o1.0 log cfu/cm after 30 d storage and remained at this level throughout 90 d storage. These results should be useful in developing guidelines for jerky preparation by consumers and processors. r 2003 Swiss Society of Food Science and Technology. Published by Elsevier Science Ltd. All rights reserved.