Kelly J. K. Getty

Effect of Packaging and Storage Time on Survival of Listeria monocytogenes on Kippered Beef Steak and Turkey Tenders

UNLABELLED The objective of our study was to determine effect of packaging method and storage time on reducing Listeria monocytogenes in shelf-stable meat snacks. Commercially available kippered beef steak strips and turkey tenders were dipped into a 5-strain L. monocytogenes cocktail, and dried at 23 °C until a water activity of 0.80 was achieved. Inoculated samples were packaged with 4 treatments: (1) vacuum, (2) nitrogen flushed with oxygen scavenger, (3) heat sealed with oxygen scavenger, and (4) heat sealed without oxygen scavenger. Samples were stored at 23 °C and evaluated for L. monocytogenes levels at 0, 24, 48, and 72 h. Initial levels (time 0) of L. monocytogenes were approximately 5.7 log CFU/cm² for steak and tenders. After 24 h of storage time, a 1 log CFU/cm² reduction of L. monocytogenes was observed for turkey tenders for all packaging treatments. After 48 h, turkey tenders showed >1 log CFU/cm² reduction of L. monocytogenes for all packaging treatments except for vacuum, where only 0.9 log CFU/cm² reduction was observed. After 72 h, reductions for all packaging treatments for turkey tenders ranged from 1.5 to 2.4 log CFU/cm². For kippered beef steak, there was no interaction between the packaging treatments and all storage times (P > 0.05) whereas, time was different (P <0.05). For kippered beef steak, there was 1 log reduction of L. monocytogenes at 24 and 48 h of storage times at 23 °C for all packaging treatments and a 2.1 log CFU/ cm² L. monocytogenes reduction at 72 h of storage time. PRACTICAL APPLICATIONS Processors of kippered beef steak and turkey tenders could use a combination of vacuum or nitrogen-flushing or heat sealed with an oxygen scavenger packaging methods and a holding time of 24 h prior to shipping to reduce potential L. monocytogenes numbers by ≥1 log. However, processors should be encouraged to hold packaged product a minimum of 72 h to enhance the margin of safety for L. monocytogenes control.

Effect of Salt Reduction on Growth of Listeria monocytogenes in Meat and Poultry Systems

Reducing sodium in food could have an effect on food safety. The objective was to determine differences in growth of Listeria monocytogenes in meat and poultry systems with salt substitutes. For phase 1, fresh ground beef, pork, and turkey with NaCl, KCl, CaCl(2), MgCl(2), sea salt, or replacement salt added at 2.0% were inoculated with L. monocytogenes to determine growth/survival during 5 d at 4 °C to simulate a pre-blend process. L. monocytogenes populations significantly decreased (0.41 log CFU/g) during the storage time in beef, but no differences (P > 0.05) were observed over time in pork or turkey. Salt type did not affect (P > 0.05) L. monocytogenes populations during pre-blend storage. MgCl(2) and NaCl allowed significant growth of aerobic populations during storage. For phase 2, emulsified beef and pork products were processed with 2% NaCl, KCl, sea salt, or a NaCl/KCl blend and post-process surface-inoculated with L. monocytogenes to determine growth/survival at 4 °C for 28 d. Pork products showed significantly greater L. monocytogenes population growth at all sampling times (0, 7, 14, 21, and 28 d) than beef products, but salt type had no effect on L. monocytogenes populations with sampling times pooled for data analysis. Although salt types had no impact on L. monocytogenes populations in preblend and emulsified meat products, pork and turkey preblends and emulsified pork had greater L. monocytogenes populations compared with beef products. These studies demonstrate that sodium may not affect the safety of preblends and emulsified meat and poultry products.

Package systems and storage times serve as postlethality controls for Listeria monocytogenes on whole-muscle beef jerky and pork and beef smoked sausage sticks.

To validate how packaging and storage reduces Listeria monocytogenes on whole-muscle beef jerky and smoked pork and beef sausage sticks, four packaging systems (heat sealed [HS] without vacuum, heat sealed with oxygen scavenger, nitrogen flushed with oxygen scavenger [NFOS], and vacuum) and four ambient temperature storage times were evaluated. Commercially available whole-muscle beef jerky and smoked pork and beef sausage sticks were inoculated with a five-strain L. monocytogenes cocktail, packaged, and then stored at 25.5 °C until enumerated for L. monocytogenes at 0, 24, 48, and 72 h and 30 days after packaging. The interaction of packaging and storage time affected L. monocytogenes reduction on jerky, but not on sausage sticks. A >2-log CFU/cm(2) reduction was achieved on sausage sticks after 24 h of storage, regardless of package type, while jerky had <2-log reductions for all packaging types. At 48 h, log reductions were similar (P. 0.05) for all types of jerky packaging, ranging from 1.26 to 1.72 log CFU/cm(2); however, at 72 h, mean L. monocytogenes reductions were >2 log CFU/cm(2), except for NFOS (1.22-log CFU/cm(2) reduction). Processors could package beef jerky in HS packages with oxygen scavenger or vacuum in conjunction with a 24-h holding time as an antimicrobial process to ensure a >1-log CFU/cm(2) L. monocytogenes reduction or use a 48-h holding time for HS- or NFOS-packaged beef jerky. A >3-log CFU/cm(2) mean reduction was observed for all beef jerky and sausage stick packaging systems after 30 days of 25.5 °C storage.

Evaluation of sample preparation methods for water activity determination in jerky and kippered beef: a research note.

Commercially available packaged whole muscle beef jerky, chopped and formed beef jerky, and kippered beef steak were obtained from retail stores to determine the effect of two sample preparation methods on water activity (a(w)). Intact samples were prepared by cutting product into a hexagonal shape with a 3.2 cm diameter. Diced samples were prepared by cutting the product into 0.4 x 0.4 cm squares. Whole muscle jerky a(w) was higher (0.016 units; P<0.001) using the intact method compared to the diced method. There was no difference (P>0.05) in a(w) levels between the two preparation methods for chopped and formed jerky or kippered beef steak. An intact sample preparation method is recommended for a(w) determination of whole muscle jerky to obtain a more conservative value, especially if a(w) is near the margin of safety.

Evaluation of Two Thermal Processing Schedules at Low Relative Humidity for Elimination of Escherichia coli O157:H7 and Salmonella Serovars in Chopped and Formed Beef Jerky†

Foodborne outbreaks have been linked to jerky produced under insufficient thermal processing schedules. Reduction of Escherichia coli O157:H7 and Salmonella serovars during thermal processing of chopped and formed beef jerky was evaluated under two processing schedules representative of those used by large-scale (LS) and small-scale (SS) jerky production facilities. Fresh chopped and formed all-beef jerky batter was inoculated with 5.8 to 7.3 log CFU of E. coli O157:H7 or Salmonella per g, extruded into strips, and thermally processed by LS or SS schedules. A >or=5.0-log CFU/g reduction of both pathogens occurred with <10% relative humidity and a cumulative process of 44 min at 55.6 degrees C followed by 46 min at 77.8 degrees C into the LS schedule. Additional drying at 77.8 degrees C for 3.5 h was needed to achieve a water activity of 0.67 and a moisture-to-protein ratio (MPR) of 0.77. For the SS process, a >or=5.0-log CFU/g reduction of both pathogens occurred with 15 to 20% relative humidity and a cumulative process of 45 min at 52 degrees C, 60 min at 57 degrees C, 45 min at 60 degrees C, 45 min at 63 degrees C, 90 min at 68 degrees C, and finishing with 30 min at 77 degrees C. After processing for an additional 90 min at 77 degrees C, water activity was 0.60 while the MPR was 0.82. The LS and SS processes for producing chopped and formed jerky provided >or=5.0 log lethality to control E. coli O157:H7 and Salmonella. However, both processes would require additional drying to achieve an MPR of 0.75 to be labeled as jerky.

Comparing the mannitol-egg yolk-polymyxin agar plating method with the three-tube most-probable-number method for enumeration of Bacillus cereus spores in raw and high-temperature, short-time pasteurized milk.

The U.S. Food and Drug Administrations Bacteriological Analytical Manual recommends two enumeration methods for Bacillus cereus: (i) standard plate count method with mannitol-egg yolk-polymyxin (MYP) agar and (ii) a most-probable-number (MPN) method with tryptic soy broth (TSB) supplemented with 0.1% polymyxin sulfate. This study compared the effectiveness of MYP and MPN methods for detecting and enumerating B. cereus in raw and high-temperature, short-time pasteurized skim (0.5%), 2%, and whole (3.5%) bovine milk stored at 4°C for 96 h. Each milk sample was inoculated with B. cereus EZ-Spores and sampled at 0, 48, and 96 h after inoculation. There were no differences (P > 0.05) in B. cereus populations among sampling times for all milk types, so data were pooled to obtain overall mean values for each treatment. The overall B. cereus population mean of pooled sampling times for the MPN method (2.59 log CFU/ml) was greater (P < 0.05) than that for the MYP plate count method (1.89 log CFU/ml). B. cereus populations in the inoculated milk samples ranged from 2.36 to 3.46 and 2.66 to 3.58 log CFU/ml for inoculated milk treatments for the MYP plate count and MPN methods, respectively, which is below the level necessary for toxin production. The MPN method recovered more B. cereus, which makes it useful for validation research. However, the MYP plate count method for enumeration of B. cereus also had advantages, including its ease of use and faster time to results (2 versus 5 days for MPN).

Sanitizing in Dry-Processing Environments Using Isopropyl Alcohol Quaternary Ammonium Formula

Dry-processing environments are particularly challenging to clean and sanitize because introduced water can favor growth and establishment of pathogenic microorganisms such as Salmonella. Our objective was to determine the efficacy of an isopropyl alcohol quaternary ammonium (IPAQuat) formula for eliminating potential Salmonella contamination on food contact surfaces. Clean stainless steel coupons and conveyor belt materials used in dry-processing environments were spot inoculated in the center of coupons (5 by 5 cm) with a six-serotype composite of Salmonella (approximately 10 log CFU/ml), subjected to IPAQuat sanitizer treatments with exposure times of 30 s, 1 min, or 5 min, and then swabbed for enumeration of posttreatment survivors. A subset of inoculated surfaces was soiled with a breadcrumb-flour blend and allowed to sit on the laboratory bench for a minimum of 16 h before sanitation. Pretreatment Salmonella populations (inoculated controls, 0 s treatment) were approximately 7.0 log CFU/25 cm(2), and posttreatment survivors were 1.31, 0.72, and < 0.7 (detection limit) log CFU/25 cm(2) after sanitizer exposure for 30 s, 1 min, or 5 min, respectively, for both clean (no added soil) and soiled surfaces. Treatment with the IPAQuat formula using 30-s sanitizer exposures resulted in 5.68-log reductions, whereas >6.0-log reductions were observed for sanitizer exposures of 1 and 5 min. Because water is not introduced into the processing environment with this approach, the IPAQuat formula could have sanitation applications in dry-processing environments to eliminate potential contamination from Salmonella on food contact surfaces.

Packaging systems and storage times serveas post-lethality treatments for Listeriamonocytogenes on whole muscle beef jerky

Introduction Following several outbreaks involving Listeria monocytogenes in ready-to-eat meat and poultry products, the United States Department of Agriculture Food Safety and Inspection Service required that processors of these products implement post-processing intervention strategies for controlling L. monocytogenes. The USDA defines a postlethality treatment as a process that reduces L. monocytogenes by at least 1 log. Research has shown that packaging can generate a 1 log L. monocytogenes reduction following 1 or more weeks of storage at room temperature. The objective of our study was to determine the effect of packaging system and storage time on reducing L. monocytogenes on shelf-stable whole muscle jerky.

Packaging systems and storage times serve as post-lethality treatments for Listeria monocytogenes on kippered beef steaks

Introduction Following several outbreaks involving Listeria monocytogenes in ready-to-eat meat and poultry products, the United States Department of Agriculture Food Safety and Inspection Service required that processors of these products implement post-processing intervention strategies for controlling L. monocytogenes. The USDA defines a postlethality treatment as a process that reduces L. monocytogenes by at least 1 log. Research has shown that packaging can generate a 1 log L. monocytogenes reduction following 1 or more weeks of storage at room temperature. The objective of our study was to determine the effect of packaging system and storage time on reducing L. monocytogenes in shelf-stable kippered beef steak.

Thermal process with additional drying provides proper lethality for controlling pathogens during jerky production

Introduction The New Mexico Department of Health linked salmonellosis to beef jerky in 2003 after 26 individuals became ill; this prompted a recall of nearly 21,600 lb of product. Following this incident, the USDA’s Food Safety and Inspection Service instituted the Compliance Guideline for Meat and Poultry Jerky Produced by Small and Very Small Plants in 2004 and updated this document in 2007 with the Quick Guide on Jerky Processing. The Quick Guide states that water activity for jerky products should be ≤ 0.85 for safety and a moisture-to-protein ratio (MPR) must be ≤ 0.75:1 for product to be labeled as jerky. Small meat processing businesses that produce jerky products must validate that their processes achieve a ≥ 5-log reduction of Escherichia coli O157:H7 and a ≥ 6.5-log reduction of Salmonella spp. Therefore, the objective of this study was to determine effects of a worst-case scenario thermal processing schedule on reducing E. coli O157:H7 and Salmonella spp. in chopped and formed beef jerky.