In this study we tested the validity of the National Organic Program (NOP) requirement for a >120-day interval between application of noncomposted manure and harvesting of vegetables grown in manure-fertilized soil. Noncomposted bovine manure was applied to 9.3-m 2 plots at three Wisconsin sites (loamy sand, silt loam, and silty clay loam) prior to spring and summer planting of carrots, radishes, and lettuce. Soil and washed (30 s under running tap water) vegetables were analyzed for indigenous Escherichia coli. Within 90 days, the level of E. coli in manure-fertilized soil generally decreased by about 3 log CFU/g from initial levels of 4.2 to 4.4 log CFU/g. Low levels of E. coli generally persisted in manure-fertilized soil for more than 100 days and were detected in enriched soil from all three sites 132 to 168 days after manure application. For carrots and lettuce, at least one enrichment-negative sample was obtained <100 days after manure application for 63 and 88% of the treatments, respectively. The current >120-day limit provided an even greater likelihood of not detecting E. coli on carrots (>1 enrichment-negative result for 100% of the treatments). The rapid maturation of radishes prevented conclusive evaluation of a 100-or 120-day application-to-harvest interval. The absolute absence of E. coli from vegetables harvested from manure-fertilized Wisconsin soils may not be ensured solely by adherence to the NOP >120-day limit. Unless pathogens are far better at colonizing vegetables than indigenous E. coli strains are, it appears that the risk of contamination for vegetables grown in Wisconsin soils would be elevated only slightly by reducing the NOP requirement to >100 days.

The survival of Listeria monocytogenes was evaluated on 15 ready-to-eat meat products made using drying, fermentation, and/or smoking. The products were obtained from six processors and included summer sausage, smoked cured beef, beef jerky, snack stick, and pork rind and crackling products. The water activity of the products ranged from 0.27 (pork rinds and cracklings) to 0.98 (smoked cured beef slices). Products were inoculated with a five-strain cocktail of L. monocytogenes, repackaged under either vacuum or air, and then stored either at room temperature (21ЊC) or under refrigeration (5ЊC) for 4 to 11 weeks. Numbers of L. monocytogenes fell for all products during storage, ranging from a decrease of 0.8 log CFU on smoked cured beef slices during 11 weeks under vacuum at 5ЊC to a decrease of 3.3 log CFU on a pork rind product stored 5 weeks under air at 21ЊC. All of the products tested could be produced under alternative 2 of the U.S. Department of Agriculture regulations mandating control of L. monocytogenes on ready-to-eat meat and poultry products. For many of the products, 1 week of postprocessing storage prior to shipment would act as an effective postlethality treatment and would allow processors to operate under alternative 1 of these regulations.On 6 June 2003, the U.S. Department of Agriculture (USDA) published an interim final rule addressing the control of Listeria monocytogenes on ready-to-eat (RTE) meat and poultry products (2). This rule went into effect 6 October 2003 and has already had a major effect on processors of these products. The rule is intended to encourage processors of RTE products to take one or more specific steps to ensure the absence of L. monocytogenes from their products. These steps range from focused sanitation steps to formulation or processing steps designed to kill L. monocytogenes or inhibit its growth. The processor is also required to test for L. monocytogenes or Listeria spp. on food-contact surfaces in the area of the plant in which RTE products are handled after cooking. The amount of testing is related to the type of RTE product, product ingredients, and how the products are processed and handled. In particular, the rule requires processors of RTE meat and poultry products to adopt one of three designated alternatives for control of L. monocytogenes on their products. The alternatives involve various levels of control and microbiological testing. Under alternative 1, the processor uses a postlethality treatment that reduces or eliminates L. monocytogenes and uses an antimicrobial agent or process that suppresses or limits L. monocytogenes growth throughout product shelf life. Under alternative 2, the processor uses either a postlethality treatment that reduces or eliminates L. monocytogenes or uses an antimicrobial agent or process that suppresses or limits L. monocytogenes growth through-* Author for correspondence. Tel: 608-265-4801; Fax: 608-262-6872; E-mail: scingham@wisc.edu.out product shelf life. Under alternative 3, only sanitation measures are rel...

The U.S. Department of Agriculture has cautioned against slow cooking meat such that the interior temperature increases from 10 degrees C (50 degrees F) to 54.4 degrees C (130 degrees F) in > or = 6 h. During a commercial ham-smoking process, the ham cold point is typically between 10 and 54.4 degrees C for 13 h, but the ham is subsequently exposed to heating sufficient to eliminate vegetative pathogenic bacteria. Thus, production of heat-stable staphylococcal enterotoxin is the primary biological hazard. For this study, uncooked surface and uncooked ground interior ham were inoculated with a three-strain Staphylococcus aureus mixture, exposed to simulated surface and interior slow-cook conditions, respectively, and analyzed periodically using the Baird-Parker agar and 3M Petrifilm Staph Express count plate methods. For the surface and interior conditions, S. aureus numbers increased by no more than 0.1 and 0.7 log units, respectively. Predictions derived from actual time and temperature data and S. aureus growth values from a computer-generated model (Pathogen Modeling Program 6.1, U.S. Department of Agriculture) were for 2.7 (ham surface) and 9.9 to 10.5 (ham interior) generations of S. aureus growth, indicating that use of model-derived growth values would not falsely indicate safe slow cooking of ham. The Baird-Parker method recovered significantly (P< 0.05) greater numbers of S. aureus than the Petrifilm Staph Express method. For hams pumped with brine to attain (i) 18% (wt/wt) weight gain, (ii) > or = 2.3% sodium lactate, (iii) > or = 0.8% sodium chloride, and (iv) 200 ppm ingoing sodium nitrite, slow-cooking critical limits of < or = 4 h between 10 and 34 degrees C, < or = 5 h between 34 and 46 degrees C, and < or = 5 h between 46 and 54.4 degrees C could be considered adequate to ensure safety.

Small amounts (10–25 g; 6.3–20.8 cm2 inoculated area) of raw ground beef, intact beef, pork and chicken (dark and white meat),and bratwurst and cured corned beef were inoculated with Salmonella serovars and Escherichia coli O157:H7, refrigerated 24 h at 5C, and then held either at 10C (± 1C) for up to 8 h or at room temperature (22C ± 2C) for up to 2 h. Except for a 0.2 log CFU increase in Salmonella serovars in ground beef during 2 h at room temperature, pathogens did not grow. Results of trials with commercial amounts of beef, pork, chicken, ground beef and bratwurst exposed to 10C for 8 h or 22C for 2 h also showed no pathogen growth. Potential critical limits for processing of previously refrigerated raw meat products are exposure temperatures between 5 and 10C for not more than 8 h or between 5 and 22C for not more than 2 h.