Judy A. Harrison

Fate of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella typhimurium during preparation and storage of beef jerky

The fate of Escherichia coli O157:H7, Listeria monocytogenes , and Salmonella typhimurium during preparation and storage of beef jerky was determined. Control strips and one-half of the inoculated beef loin strips were marinated at 4°C overnight and dried at 60°C (140°F) for 10h. The remaining half of the inoculated samples were heated in marinade to 71.1°C (160°F). Strips were dried at 60°C (140°F) for 10 h. Microbial populations were determined at intervals during drying up to 10 h and also from samples stored at 25°C for 8 weeks at various moisture levels. In general, L. monocytogenes was more resistant to the treatments. After 3 h of drying, populations on the unheated, inoculated samples were reduced by 3.3, 1.8 and 3.1 log units, respectively, and all three were reduced by 5.5 to 6.0 log units after 10h. Reduction of the three populations on strips that were cooked prior to drying was 4.5 to 5.5 log units immediately after cooking. The populations decreased to undetectable levels after 10 h of drying. None of the three pathogens were detected on the controls. After 8 weeks of storage none of the pathogens were detected, indicating that they were unable to recover under the moisture conditions during storage.

Effects of preparation methods on the microbiological safety of home-dried meat jerky.

Historically, drying meats to produce jerky was conisidered to be a safe preservation process and the convenience and flavor of jerky has made it a popular food product for home food preservers. Recent outbreaks of foodborne illness related to both home-dried and commercially manufactured jerky have raised concerns about the safety of the product. Some traditional home recipes and drying processes were shown to be inadequate to destroy Escherichia coli O157, Salmonella, Staphylococcus aureus, and Listeria monocytogenes in both whole-muscle and ground-meat jerky. Several research studies have identified processes such as precooking meats before drying, usingacidic marinades, cooking meats after drying, or some combination of these treatments that can destroy pathogens of concern to produce microbiologically safe and palatable meat jerky at home.

Home-Style Beef Jerky: Effect of Four Preparation Methods on Consumer Acceptability and Pathogen Inactivation

The safety of homemade jerky continues to be questioned. Producing a safe product that retains acceptable quality attributes is important. Lethality of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes as well as consumer acceptability and sensory attributes of jerky prepared by four methods were examined. Preparation methods were drying marinated strips at 60 degrees C (representing a traditional method), boiling strips in marinade or heating in an oven to 71 degrees C prior to drying, and heating strips in an oven after drying to 71 degrees C. A 60-member consumer panel rated overall acceptability. A 10-member descriptive panel evaluated quality attributes. Samples heated after drying and samples boiled in marinade prior to drying had slightly higher acceptability scores but were not statistically different from traditional samples. Although the four treatments were significantly different in color (P = 0.0001), saltiness (P = 0.0001), and texture (P = 0.0324), only texture appeared to influence overall consumer acceptability. Microbial challenge studies subjecting the pathogens to the four treatments showed a 5.8-, 3.9-, and 4.6-log reduction of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively, even with traditional drying. Oven treatment of strips after drying was shown to have the potential to reduce pathogen populations further by approximately 2 logs. In conclusion, a safer, yet acceptable home-dried beef jerky product can be produced by oven-heating jerky strips after drying.

Fate of Listeria monocytogenes and Salmonella species in ground beef jerky

Home-style drying procedures used for jerky made from whole meat strips may be insufficient to eliminate bacterial pathogens from jerky made from ground meat due to the possible distribution of pathogens throughout the product. The fate of Listeria monocytogenes and Salmonella species during preparation of ground beef jerky was determined. Ground beef was inoculated with these pathogens to a level of approximately 106 CFU/g prior to drying. A drying method shown to reduce the population of these microorganisms by 5 log CFU/g on jerky made with beef loin strips in a home-style dehydrator maintained at 60°C (140°F) was used with unheated samples and samples heated to 71.1°C (160°F) prior to drying, with and without cure mix. Populations of each pathogen type were determined after 0, 2, 4, 6 and 8 h of drying. In unheated samples without cure mix, there was only a 2.5 to 4 log reduction in the pathogens after 8 h of drying. When cure mix was added, the populations were reduced by at least 4 logs. Population reductions in heated samples without cure were approximately 3.8 log CFU/g for Salmonella and Listeria . Addition of the cure mix resulted in a greater reduction in Salmonella populations in the heated samples.

Survival of Escherichia coli O157:H7 in ground beef jerky assessed on two plating media.

Recent outbreaks of food-borne illness due to Salmonella spp. in beef jerky and Escherichia coli O157:H7 in venison jerky, coupled with the fact that a variety of preparation methods and dying procedures abound, raise concern over the safety of processed meat products made in the home. The potential of injured bacterial cells to regain the ability to cause illness is a particular threat with pathogens such as E. coli O157:H7, which is believed to have a low infectious dose. This study examined the efficacy of various methods of jerky preparation in reducing populations of E, coli O157:H7 in ground beef jerky and compared the recovery rate of E. coli O157:H7 on two selective plating media, modified sorbitol MacConkey agar (MSMA) and modified eosin methylene blue agar (MEMB). Populations of E. coli O157:H7 in both heated and unheated samples exhibited a greater decline during drying when a nitrite and salt cure mix was added during jerky preparation. When recovery of E. coli O157:H7 on MSMA and MEMB was compared, a trend toward slightly higher recovery rates with MEMB was observed. On the basis of these results, MEMB is a suitable alternative to MSMA for the recovery of E. coli O157:H7 from heated and dried meat samples similar to beef jerky.

Sanitizer Efficacy against Murine Norovirus, a Surrogate for Human Norovirus, on Stainless Steel Surfaces when Using Three Application Methods

ABSTRACT Human noroviruses are major etiologic agents of epidemic gastroenteritis. Outbreaks are often accompanied by contamination of environmental surfaces, but since these viruses cannot be routinely propagated in laboratory cultures, their response to surface disinfectants is predicted by using surrogates, such as murine norovirus 1 (MNV-1). This study compared the virucidal efficacies of various liquid treatments (three sanitizer liquids, 5% levulinic acid plus 2% SDS [LEV/SDS], 200 ppm chlorine, and an isopropanol-based quaternary ammonium compound [Alpet D2], and two control liquids, sterile tap water and sterile tap water plus 2% SDS) when delivered to MNV-1-inoculated stainless steel surfaces by conventional hydraulic or air-assisted, induction-charged (AAIC) electrostatic spraying or by wiping with impregnated towelettes. For the spray treatments, LEV/SDS proved effective when applied with hydraulic and AAIC electrostatic spraying, providing virus reductions of 2.71 and 1.66 log PFU/ml, respectively. Alpet D2 provided a 2.23-log PFU/ml reduction with hydraulic spraying, outperforming chlorine (1.16-log PFU/ml reduction). Chlorine and LEV/SDS were equally effective as wipes, reducing the viral load by 7.05 log PFU/ml. Controls reduced the viral load by <1 log with spraying applications and by >3 log PFU/ml with wiping. Results indicated that both sanitizer type and application methods should be carefully considered when choosing a surface disinfectant to best prevent and control environmental contamination by noroviruses.

Listeria monocytogenes survival in refrigerator dill pickles.

Listeria monocytogenes can survive and grow in refrigerated foods with pH values of approximately 4.0 to 5.0 and salt concentrations of 3 to 4%. Home-fermented refrigerator dill pickles fit this description. Contamination of this product with L. monocytogenes could cause serious problems because these items are not heated prior to consumption. L. monocytogenes survival and growth patterns were investigated in refrigerator dill pickles at 1.3, 3.8, and 7.6% salt concentrations. Pickling cucumbers were dipped into an inoculum of L. monocytogenes, brine mixtures were added, and cucumbers were held at room temperature for 1 week and then refrigerated for up to 3 months. The pH, NaCl percentage, titratable acidity percentage, and total populations of Listeria and aerobic, psychrotrophic, and lactic acid bacteria were measured at the addition of brine, after 2, 4, and 7 days of storage at room temperature, and then weekly during refrigerated storage. The initial Listeria population was 5.4 to 5.6 log CFU/cm2 on cucumber surfaces and 3.9 to 4.6 log CFU/g internally. There was an approximate 0.3- to 1-log increase during room temperature fermentation followed by a population decline during refrigerator storage, with a greater decrease in the brines with the highest NaCl concentration. Up to 49 days, the internal tissue of pickles with 1.3, 3.8, or 7.6% salt concentrations were presumptively positive for L. monocytogenes by the enrichment method, and at 91 days the surfaces of such pickles were still positive for L. monocytogenes. Populations of total aerobes and lactic acid bacteria increased during room temperature storage and decreased gradually during refrigerated storage.

RNA synthesized during late sporulation is required for germ tube formation inBlastocladiella emersonii

Abstract Inhibition of RNA synthesis with actinomycin D as late as 210 min ( T 210 ) after Blastocladiella emersonii is induced to sporulate results in complete blockage of germ tube formation in the next generation. In agreement with other reports, actinomycin D added during germination did not block germ tube formation. Protein synthesis during germination is reduced by approximately one-half when actinomycin D is added at T 210 but remains at virtually control levels when actinomycin D is added during germination. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel analyses of the abundant proteins synthesized in vivo during the first hour of germination revealed no qualitative differences in the proteins which accumulate when control cells are compared to cells treated with actinomycin D at T 210 . Comparison of proteins synthesized from 20 to 40 min germination vs 40 to 60 min germination demonstrated that actinomycin D alters the temporal pattern of accumulation of some abundant proteins. The RNA synthesized after T 210 is associated with polysomes, suggesting that an mRNA fraction made in late sporulation is required for a germ tube. The available data do not exclude the possibility that a regulatory RNA synthesized during late sporulation is required for germ tube formation.

Food Safety Hazards Identified on Small Farms

Farmers markets have increased in number in the U.S. by almost 400% since the early 1990s. Customers shop at these markets to get to know the farmers who are producing their food, and to purchase products they view as more nutritious, better tasting, higher quality, better for the environment and safer than foods from larger, commercial farms being sold in supermarkets. Yet studies in the U.S. and in other countries have identified food safety hazards on farms and in farmers markets that may increase the risk of foodborne illnesses. Risky practices on farms include the use of raw manure without appropriate waiting periods observed between application and harvest, use of untested well or surface water for irrigation and/or washing of produce, lack of sanitary facilities and handwashing facilities for workers, lack of training for workers, food contact surfaces not properly cleaned and sanitized and lack of temperature control both on the farm and during transport to market. Hazards have also been identified with livestock and poultry products such as lack of sanitation and temperature control. A lack of sanitation practices and microbial problems associated with the use of raw milk have been identified as hazards on farms making and selling artisanal cheeses.

Potential Food Safety Hazards in Farmers Markets

Consumers often view foods sold at farmers markets as healthier and safer than foods produced and shipped long distances and sold in stores. However, outbreaks of foodborne illnesses have occurred from products sold at farmers markets. Studies in the U.S. have shown that rules regarding farmers markets and the food products allowed for sale vary from state to state. A survey of farmers market managers found that few have written food safety plans for their market, and many managers do not ask questions of growers or vendors as to how products are produced or processed. Products in U.S. markets include fresh produce and products made in small businesses, many of which may be operated in home kitchens under cottage food regulations. Studies indicate that threats to the safety of products sold in farmers markets can be categorized into threats from the environment, threats due to the infrastructure or facilities and threats from people—both vendors and customers. Observations have included a lack of handwashing and sanitation, lack of refrigeration, pets in the market, vendors eating and drinking while handling foods and other issues that could put customers at risk. Regulatory personnel and Extension food safety educators responding to a survey indicated that it is prevalent to very prevalent for owner/operators (55–74%) with whom they work to view their products as unlikely to cause illness because their businesses are small, local or organic. However, respondents noted a lack of food safety knowledge, including knowledge of allergens, required labeling and other regulatory requirements among these vendors. These and other practices could put customers in farmers markets at greater risk for foodborne illnesses.