National Beef Quality Audit-2022 Phase 1: face-to-face and digital interviews.

The National Beef Quality Audit (NBQA) has been conducted regularly since 1991 to assess and benchmark quality in the U.S. beef industry, with the most recent iteration conducted in 2022. The goal of NBQA Phase I is to evaluate what needs to be managed to improve beef quality and demand. Interviews (n = 130) of industry personnel were conducted with the aid of routing software. In total, packers (n = 24), retailers (n = 20), further processors (n = 26), foodservice (n = 18), and allied government agencies and trade organizations (n = 42) were interviewed. Interviews were routed in software based on interviewee involvement in either the fed steer and heifer market cow and bull sectors, or both. Interviews were structured to elicit random responses in the order of determining "must-have" criteria (quality factors that are required to make a purchase), best/worst ranking (of quality factors based on importance), how interviewees defined quality terms, a strength, weakness, opportunities, threats (SWOT) analysis, general beef industry questions, and sustainability goals (the latter four being open-ended). Quality factors were 1) visual characteristics, 2) cattle genetics, 3) food safety, 4) eating satisfaction, 5) animal well-being, 6) weight and size, and 7) lean, fat, and bone. Best/worst analysis revealed that "food safety" was the most (P < 0.05) important factor in beef purchasing decisions for all market sectors and frequently was described as "everything" and "a way of business." Culture surrounding food safety changed compared to previous NBQAs with interviewees no longer considering food safety as a purchasing criterion, but rather as a market expectation. The SWOT analysis indicated that "eating quality of U.S. beef" was the greatest strength, and cited that educating both consumers and producers on beef production would benefit the industry. Irrespective of whether companies' products were fed or market cow/bull beef, respondents said that they believed "environmental concerns" were among the major threats to the industry. Perceived image of the beef industry in the market sectors has improved since NBQA-2016 for both fed cattle and market cow/bull beef.

National Beef Quality Audit-2022: Transportation, mobility, live cattle, and hide assessments to determine producer-related defects that affect animal welfare and the value of market cows and bulls at processing facilities.

The National Beef Quality Audit (NBQA)-2022 serves as a benchmark of the current market cow and bull sectors of the U.S. beef industry and allows comparison to previous audits as a method of monitoring industry progress. From September 2021 through May 2022, livestock trailers (n = 125), live animals (n = 5,430), and post-slaughter hide-on animals (n = 6,674) were surveyed at 20 commercial beef processing facilities across the U.S. Cattle were transported in a variety of trailer types for an average distance of 490.6 km and a mean transport time of 6.3 h. During transit, cattle averaged 2.3 m2 of trailer space per animal indicating sufficient space was provided according to industry guidelines. Of all trailers surveyed, 55.3% transported cattle from an auction barn to a processing facility. When surveyed, 63.6% of all truck drivers reported to be Beef Quality Assurance certified. The majority (77.0%) of cattle were sound when evaluated for mobility. Mean body condition scores (9-point scale) for beef cows and bulls were 3.8 and 4.4, respectively, whereas mean body condition scores (5-point scale) for dairy cows and bulls were 2.3 and 2.6, respectively. Of the cattle surveyed, 45.1% had no visible live animal defects, and 37.9% had only a single defect. Of defects present in cows, 64.6% were attributed to an udder problem. Full udders were observed in 47.5% of all cows. Nearly all cattle were free of visible abscesses and knots (97.9% and 98.2%, respectively). No horns were observed in 89.4% of all cattle surveyed. Beef cattle were predominantly black-hided (68.9% and 67.4% of cows and bulls, respectively). Holstein was the predominant dairy animal observed and accounted for 85.7% of the cows and 98.0% of the bulls. Only 3.1% of all animals had no form of identification. Findings from the NBQA-2022 show improvements within the industry and identify areas that require continued education and research to improve market cow and bull welfare and beef quality.

Liver abscess microbiota of feedlot steers finished in natural and traditional management programs.

Liver abscess etiology in feedlot steers involves the escape of bacteria from the digestive tract to form a polymicrobial abscess within or on the external surface of the liver. However, little is known about the effects of feedlot finishing systems on the microbial composition of the liver abscess purulent material. Liver abscesses were collected at the time of harvest from steers originating from a single feedlot managed in either a traditional program (which included tylosin phosphate supplementation) or a natural program (without tylosin phosphate supplementation). The purulent material of liver abscesses from traditionally managed steers (N = 53 abscesses) and that of naturally managed steers (N = 62 abscesses) was characterized using the V4 region of the 16S rRNA gene. Two phyla and three genera were found in greater than 1% relative abundance across all abscesses. The genus Fusobacterium was identified in all liver abscess samples and accounted for 64% of sequencing reads. Bacteroides and Porphyromonas genera accounted for 33% and 1% of reads, respectively. Trueperella was more likely to be found in the liver abscesses of naturally managed steers than traditionally managed steers (P = 0.022). Over 99% of the genus-level bacterial sequences observed across all liver abscesses belonged to Gram-negative genera. Bacteria known to colonize both the rumen and hindgut were identified within liver abscesses. No differences in alpha diversity or beta diversity were detected between liver abscess communities (between the two management programs or individual pens) when tested as richness, Shannon Diversity Index, or weighted UniFrac distances (P > 0.05). These results were consistent with previous identification of Fusobacterium necrophorum as the primary bacteriologic agent within liver abscesses and emphasized the relationship between the gastrointestinal microbiota and liver abscess formation. Though the microbiota of the liver abscess purulent material was similar between steers fed an antibiotic-free diet and those fed an antibiotic-containing diet from the same feedlot, divergence was detected in liver abscess communities with some being dominated by Fusobacterium and others being dominated by Bacteroides.

As feedlot cattle consume grain, the rumen becomes more acidic. If the lining of the digestive tract is damaged, bacteria that normally remain in the digestive tract can enter the body. Certain bacteria like Fusobacterium necrophorum are involved in the formation of liver abscesses. Feedlot cattle are commonly fed an antibiotic (tylosin phosphate) to reduce the occurrence of liver abscesses, but increasing scrutiny is placed on the antibiotic use. However, the effect of eliminating the antibiotic used to prevent liver abscesses on the bacterial communities involved in liver abscess formation is unknown. This study compared the bacteria found within liver abscesses of cattle fed tylosin phosphate with that of cattle not fed tylosin phosphate. All liver abscesses contained F. necrophorum, and Bacteroides was the second most commonly identified bacterium. Trace amounts of bacteria known to colonize the mouth and digestive tract were observed. Trueperella, a bacteria targeted by tylosin phosphate, was found more frequently in liver abscesses from cattle that received no antibiotic. While the core bacterial composition of the liver abscess was unaffected by antibiotic supplementation to feedlot steers, reduced Trueperella in liver abscesses from cattle-fed tylosin phosphate could be related to a reduction in liver abscess prevalence.

Reduction of Listeria monocytogenes on frankfurters treated with lactic acid solutions of various temperatures.

United States regulations require ready-to-eat meat and poultry processors to control Listeria monocytogenes using interventions which may include antimicrobials that reduce post-processing contamination by at least 1 log-cycle; if the treatment achieves > or = 2 log reductions, the plant is subject to less frequent microbial testing. Lactic acid (LA) may be useful as a post-lethality intervention and its antimicrobial properties may increase with temperature of application. The aim of this study was to evaluate the effect of LA solution concentration and temperature on L. monocytogenes counts of inoculated frankfurters and to identify parameters (concentration, temperature, and time) that achieve 1 and 2 log-unit immediate reductions. Frankfurters were surface-inoculated with a 10-strain mixture of L. monocytogenes (4.4 +/- 0.1 log CFU/cm(2)) and then immersed in distilled water or LA solutions (0-3%) of 4, 25, 40, or 55 degrees C for 0-120 s. A regression equation for L. monocytogenes reduction included significant (P < 0.05) effects by the terms of concentration, time, temperature, and the interaction of concentration and temperature; other tested parameters (other interactions, quadratic and cubic terms), within the experimental range examined, did not affect (P > or = 0.05) the extent of reduction. Results indicated that the effectiveness of LA against L. monocytogenes, in addition to concentration, increased with solution temperature (in the range of 0.6-2.8 log CFU/cm(2)). The developed equation may allow processors to vary conditions of treatment with LA to achieve a 1 or 2 log-unit reduction of the pathogen and comply with United States regulations.

Modeling the growth/no-growth boundaries of postprocessing Listeria monocytogenes contamination on frankfurters and bologna treated with lactic acid.

This study developed models to predict lactic acid concentration, dipping time, and storage temperature combinations determining growth/no-growth interfaces of Listeria monocytogenes at desired probabilities on bologna and frankfurters. L. monocytogenes was inoculated on bologna and frankfurters, and 75 combinations of lactic acid concentrations, dipping times, and storage temperatures were tested. Samples were stored in vacuum packages for up to 60 days, and bacterial populations were enumerated on tryptic soy agar plus 0.6% yeast extract and Palcam agar on day zero and at the end point of storage. The combinations that allowed L. monocytogenes increases of >or=1 log CFU/cm(2) were assigned the value of 1 (growth), and the combinations that had increases of

Fate of post-processing inoculated Listeria monocytogenes on vacuum-packaged pepperoni stored at 4, 12 or 25 degrees C.

If present, Listeria monocytogenes may not be eliminated during processing of pepperoni or may be introduced during peeling, slicing, or packaging. We evaluated the fate of the pathogen on sliced inoculated pepperoni during vacuum-packaged storage, and potential differences in survival among three types of inocula, including nonacid-adapted, acid-adapted and pepperoni extract-habituated cultures. Commercial pepperoni (two replicates, three samples per treatment) was sliced and inoculated (3 to 4 log CFU/cm(2)), before vacuum-packaging and storage for up to 180 days at 4, 12 or 25 degrees C. Samples were periodically analyzed for pathogen counts (PALCAM agar) and total bacterial counts (tryptic soy agar with 0.6% yeast extract). The pH of the product was relatively stable (4.50-4.81) throughout storage. Overall, levels of the pathogen (all inocula) and total counts decreased continuously during storage at all temperatures. The pathogen died slower at 4 degrees C than at 12 and 25 degrees C, while at 12 and 25 degrees C the death rates were similar. Death rates depended on type of inoculum and generally decreased in the order: acid-adapted, extract-habituated and nonacid-adapted inoculum. At day 60, pathogen levels were below the detection limit and remained undetectable throughout the rest of the 180-day storage period, regardless of inoculum type and storage temperature. Therefore, storage of sliced vacuum-packaged pepperoni, especially at ambient temperature, prior to consumption may reduce the potential risk of listeriosis.

Effect of inoculum preparation procedure and storage time and temperature on the fate of Listeria monocytogenes on inoculated salami.

Although dry/semidry fermented sausages are characterized as being of low-to-moderate risk for human listeriosis on a per-serving and per-annum basis, data are lacking relative to the fate of postprocessing Listeria monocytogenes contamination during storage of such products. This study evaluated the effect of inoculum preparation and storage conditions on the fate of L. monocytogenes on vacuum-packaged salami. Commercially produced salami was sliced and inoculated (4 +/- 1.3 log CFU/ cm2) with one of four types of inocula. All inocula consisted of the same 10-strain L. monocytogenes composite, cultivated as individual strains prior to mixing for inoculation. Active cultures of individual strains were prepared (30 degrees C, 24 h) in either tryptic soy broth (containing 0.25% glucose) plus 0.6% yeast extract (TSBYE), tryptic soy broth without glucose plus 0.6% yeast extract (TSBYE-G), TSBYE-G plus 1% glucose (TSBYE+G), or in TSBYE, and then habituated (7 degrees C, 72 h) in sterile salami homogenate (10% [wt/wt] with distilled water). Inoculated salami slices were vacuum packaged, stored at 4, 12, or 25 degrees C, and analyzed (three samples per treatment in each of two replicates) periodically for surviving bacterial counts. In general, pathogen levels decreased during storage and reached levels below the detection limit (-0.4 log CFU/cm2) between 27 and 90 days of storage, depending on temperature of storage and inoculum type. Death rates (log CFU/cm2/day) were found to increase as storage temperature increased, with the exception of the acid-adapted (TSBYE+G) cells, which decreased more rapidly at 4 degrees C than at 12 or 25 degrees C. The habituated inoculum was inactivated at a faster rate than other inocula at 12 and 25 degrees C, but performed similarly to nonadapted (TSBYE-G) and partially acid-adapted (TSBYE) inocula at 4 degrees C. These data may be used to supplement existing information for use in future risk assessments.

Control of Listeria monocytogenes on vacuum-packaged frankfurters sprayed with lactic acid alone or in combination with sodium lauryl sulfate.

U.S. regulations require that processors employ lethal or inhibitory antimicrobial alternatives in production of ready-to-eat meat and poultry products that support growth of Listeria monocytogenes and may be exposed to the processing environment after a lethality treatment. In this study, lactic acid (LA; 5%, vol/vol) and sodium lauryl sulfate (SLS; 0.5%, wt/vol) were evaluated individually or as a mixture (LASLS) for control of L. monocytogenes on frankfurters. Frankfurters were inoculated with a 10-strain mixture of L. monocytogenes, sprayed for 10 s (20 bar, 23 +/- 2 degrees C) with antimicrobials or distilled water (DW) before (LASLS or DW) or after (LA, SLS, LASLS, or DW) inoculation (4.8 +/- 0.1 log CFU/cm2), vacuum packaged, and stored at 4 degrees C for 90 days. Samples were analyzed for numbers of the pathogen (on PALCAM agar) and for total microbial counts (on tryptic soy agar with yeast extract) during storage. Spraying with DW, LA, or SLS after inoculation reduced numbers of L. monocytogenes by 1.3 +/- 0.2, 1.8 +/- 0.5, and 2.0 +/- 0.4 log CFU/cm2, respectively. The LASLS mixture applied before or after inoculation reduced pathogen populations by 1.8 +/- 0.4 and 2.8 +/- 0.2 log CFU/cm2, respectively. No further reduction by any treatment was observed during storage. The bacterial growth curves (fitted by the model of Baranyi and Roberts) indicated that the lag-phase duration of the bacterium on control samples (13.85 to 15.18 days) was extended by spraying with all solutions containing LA. For example, LA suppressed growth of L. monocytogenes for 39.14 to 41.01 days. Pathogen growth rates also were lower on frankfurters sprayed after inoculation with LA or LASLS compared to those sprayed with DW. Therefore, spraying frankfurters with a mixture of LA and SLS may be a useful antilisterial alternative treatment for ready-to-eat meat and poultry products.

Studies to evaluate chemicals and conditions with low-pressure applications for reducing microbial counts on cattle hides.

Studies were conducted to identify effective antimicrobials and application parameters that could be used as decontamination interventions to reduce microbial loads on cattle hides before removal from carcasses. In study I, hide swatches inoculated with Escherichia coli O157:H7 were sprayed with 10% acetic acid (at 23 and 55 degrees C), 10% lactic acid (at 23 and 55 degrees C), 3% sodium hydroxide (at 23 degrees C) or 4 and 5% sodium metasilicate (at 23 degrees C). All antimicrobials were evaluated independently after being applied alone, being applied after a water rinse, or being followed by a water rinse. Antimicrobial treatments followed by a water rinse lowered E. coli O157:H7 populations by 0.6 to 2.4 log CFU/cm2 and resulted in hides with a surface pH of 6.3 to 9.2. Treatments in which a water rinse was followed by antimicrobial application lowered E. coli O157:H7 populations by 1.5 to 5.1 log CFU/cm2 but resulted in hides with a surface pH of 3.9 to 10.5. In study II, whole hides were treated with one of four antimicrobials (acetic acid, lactic acid, sodium hydroxide, or sodium metasilicate) followed by a water rinse. Hides were evaluated for aerobic bacterial counts, total coliform counts, and E. coli counts. Generally, all antimicrobials resulted in greater reductions (P < 0.05) of E. coli counts when compared with the control; however, only acetic and lactic acids resulted in greater reductions (P < 0.05) of aerobic bacterial counts and total coliform counts compared with the controls. These antimicrobials could be used to reduce microbial contamination on hides, potentially reducing microbiological contamination transferred to carcasses or to the plant environment.

Thermal inactivation of Escherichia coli O157:H7 in beef treated with marination and tenderization ingredients.

Internalization of Escherichia coli O157:H7 in nonintact beef products during mechanical tenderization or during injection of marination and tenderization ingredients is of concern if such products are undercooked. This study tested organic acids (0.2% citric acid and 0.3% acetic acid), potassium and calcium salts (1.8% potassium lactate, 0.63% calcium lactate, 0.86% calcium ascorbate, and 0.23% calcium chloride), and sodium chloride (2.5%) for their influence on thermal destruction of E. coli O157:H7 in ground beef serving as a model system. Ground beef batches (700 g; 5% fat) were mixed with equal volumes (22 ml) of each treatment solution or distilled water and portions (30 g) of treated ground beef were extruded in test tubes (2.5 by 10 cm). A five-strain mixture of E. coli O157:H7 (0.3 ml; 7 log CFU/g) was introduced at the center of the sample with a pipette. After overnight storage (4 degrees C), simulating product marination, samples were heated to 60 or 65 degrees C internal temperature, simulating rare and medium rare doneness of beef, in a circulating water bath. At 65 degrees C, treatments with citric and acetic acid showed greater (P < 0.05) reduction (4 to 5 log CFU/g) of E. coli O157:H7 than all the other ingredients and the control (3 to 4 log CFU/g). Sodium chloride reduced weight losses (16 to 18% compared with 20 to 27% by citric or acetic acid) and resulted in a 4-log reduction in counts during cooking to 65 degrees C. Ingredients such as citric or acetic acid may improve thermal inactivation of E. coli O157:H7 internalized in nonintact beef products, while sodium chloride may reduce cooking losses in such products.

Effect of acid adaptation on growth during storage at 10 degrees C and resistance to simulated gastric fluid of Listeria monocytogenes inoculated onto bologna formulated with or without antimicrobials.

The fate of acid-adapted and nonadapted Listeria monocytogenes inoculated onto bologna slices (formulated with or without antimicrobials) was examined during storage and after exposure to in vitro gastric challenge. Bologna slices formulated with no antimicrobials (control), 3% sodium lactate (SL), or 1.8% SL plus 0.25% sodium diacetate (SD) were inoculated (2 log CFU/cm2) with a 10-strain composite of acid-adapted or nonadapted L. monocytogenes strains. Growth or survival of the two inocula on bologna was evaluated during vacuum-packaged storage (10 degrees C) for up to 36 days. Survival of previously acid-adapted or nonadapted L. monocytogenes on stored bologna exposed to simulated gastric fluid (adjusted to pH 1.0 with HCl) for 20, 40, and 60 min also was determined. As expected, inclusion of antimicrobials in the product formulation inhibited growth of L. monocytogenes during storage of vacuum-packaged bologna compared with growth on control samples. Acid adaptation of L. monocytogenes prior to product inoculation did not affect subsequent survival or growth on bologna or resistance to simulated gastric fluid (P > 0.05). Survival of L. monocytogenes exposed to simulated gastric fluid during storage increased with product age, growth phase of the cells, and possibly age of the cells, particularly for control samples (no antimicrobials), in which the pathogen grew uninhibited to approximately 6 log CFU/cm2 by day 8 of storage. Inhibition of L. monocytogenes growth on product formulated with antimicrobials was associated with only sporadic and small numbers of survivors following exposure of these samples to simulated gastric fluid, especially in samples stored longer. However, cell numbers in these treatment groups before the gastric challenge did not exceed 3.8 log CFU/cm2. Inhibition of growth on product with antimicrobials precluded detection of survivors resistant to the effects of simulated gastric fluid.

Fate of Listeria monocytogenes in commercial ham, formulated with or without antimicrobials, under conditions simulating contamination in the processing or retail environment and during home storage.

Commercial cured ham formulated with or without potassium lactate and sodium diacetate was inoculated with Listeria monocytogenes and stored to simulate conditions of processing, retail, and home storage. The ham was sliced, inoculated with a 10-strain composite of L. monocytogenes (1 to 2 log CFU/cm2), vacuum packaged, and stored at 4 degrees C to simulate contamination following lethality treatment at processing (first shelf life). After 10, 20, 35, and 60 days of storage, packages were opened, samples were tested, and bags with remaining slices were reclosed with rubber bands. At the same times, portions of original product (stored at 4 degrees C in original processing bags) were sliced, inoculated, and packaged in delicatessen bags to simulate contamination during slicing at retail (second shelf life). Aerobic storage of both sets of packages at 7 degrees C for 12 days was used to reflect domestic storage conditions (home storage). L. monocytogenes populations were lower (P < 0.05) during storage in ham formulated with lactate-diacetate than in product without antimicrobials under both contamination scenarios. Inoculation of ham without lactate-diacetate allowed prolific growth of L. monocytogenes in vacuum packages during the first shelf life and was the worst case contamination scenario with respect to pathogen numbers encountered during home storage. Under the second shelf life contamination scenario, mean growth rates of the organism during home storage ranged from 0.32 to 0.45 and from 0.18 to 0.25 log CFU/cm2/day for ham without and with lactate-diacetate, respectively, and significant increases in pathogen numbers (P < 0.05) were generally observed after 4 and 8 days of storage, respectively. Regardless of contamination scenario, 12-day home storage of product without lactate-diacetate resulted in similar pathogen populations (6.0 to 6.9 log CFU/cm2) (P > 0.05). In ham containing lactate-diacetate, similar counts were found during the home storage experiment under both contamination scenarios, and only in 60-day-old product did samples from the first shelf life have higher (P < 0.05) pathogen numbers than those found in samples from the second shelf life. These results should be useful in risk assessments and for the establishment of "sell by" and "consume by" date labels for refrigerated ready-to-eat meat products.

Mobility Scoring of Finished Cattle.

Lameness is among the most important welfare and production issues affecting dairy cattle. Recently, it has received significant research emphasis. Certain events in 2013 within the cattle industry heightened the focus on mobility issues in finished cattle. Scoring systems are needed in the finished cattle industry to capture and measure mobility issues at packing facilities. The North American Meat Institute Animal Welfare Committee helped facilitate the creation of a scoring system to evaluate mobility of cattle at packing plants, providing the cattle industry with a tool to benchmark and improve the welfare of finished cattle.

Post process control of Listeria monocytogenes on commercial frankfurters formulated with and without antimicrobials and stored at 10 degrees C.

The antilisterial effect of postprocess antimicrobial treatments on commercially manufactured frankfurters formulated with and without a 1.5% potassium lactate-0.05% sodium diacetate combination was evaluated. Frankfurters were inoculated (ca. 3 to 4 log CFU/cm2) with 10-strain composite Listeria monocytogenes cultures originating from different sources. The inocula evaluated were cells grown planktonically in tryptic soy broth plus 0.6% yeast extract (30 degrees C, 24 h) or in a smoked sausage homogenate (15 degrees C, 7 days) and cells that had been removed from stainless steel coupons immersed in an inoculated smoked sausage homogenate (15 degrees C, 7 days). Inoculated frankfurters were dipped (2 min, 25 +/- 2 degrees C) in acetic acid (AA; 2.5%), lactic acid (LA; 2.5%), potassium benzoate (PB; 5%), or Nisaplin (commercial form of nisin; 0.5%, equivalent to 5,000 IU/ml of nisin) solutions, or in Nisaplin followed by AA, LA, or PB, and were subsequently vacuum packaged and stored for 48 days at 10 degrees C. In addition to microbiological analyses, sensory evaluations were performed with uninoculated samples that had been treated with AA, LA, or PB for 2 min. Initial L. monocytogenes populations were reduced by 1.0 to 1.8 log CFU/cm2 following treatment with AA, LA, or PB solutions, and treatments that included Nisaplin reduced initial levels by 2.4 to >3.8 log CFU/ cm2. All postprocessing treatments resulted in some inhibition of L. monocytogenes during the initial stages of storage of frankfurters that were not formulated with potassium lactate-sodium diacetate; however, in all cases, significant (P < 0.05) growth occurred by the end of storage. The dipping of products formulated with potassium lactate-sodium diacetate in AA or LA alone--or in Nisaplin followed by AA, LA, or PB-increased lag-phase durations and lowered the maximum specific growth rates of the pathogen. Moreover, depending on the origin of the inoculum, this dipping of products led to listericidal effects. In general, differences in growth kinetics were obtained for the three inocula that were used to contaminate the frankfurters. Possible reasons for these differences include the presence of stress-adapted subpopulations and the inhibition of the growth of the pathogen due to high levels of spoilage microflora. The dipping of frankfurters in AA, LA, or PB did not (P > 0.05) affect the sensory attributes of the product when compared to the control samples. The data generated in this study may be useful to U.S. ready-to-eat meat processors in their efforts to comply with regulatory requirements.

Fate of inoculated Escherichia coli O157:H7, cultured under different conditions, on fresh and decontaminated beef transitioned from vacuum to aerobic packaging.

This study evaluated the behavior of Escherichia coli O157:H7 during aerobic storage, after storage in vacuum packages, on beef inoculated with cultures prepared (35 degrees C, 24 h) in tryptic soy broth without dextrose (TSB), nonacid hot water carcass decontamination runoff fluids (washings; pH 6.0; WASH), cells from biofilms formed on stainless steel coupons in WASH (WETB), or WETB dried (25 degrees C, 12 h) before harvesting of cells (DRYB). These inocula were applied to fresh beef pieces (40 cm2), which were then left untreated or treated by immersion in hot water (75 degrees C) followed by 2% lactic acid (55 degrees C; hot water/lactic acid [HW/LA]), for 30 s each. Inoculated samples were vacuum packaged and stored at 0 (30, 60, or 90 days), 4 (7 or 14 days), or 12 degrees C (4 or 8 days) and subsequently transferred to retail packages for aerobic storage at 7 degrees C for 5 days. Populations of E. coli O157:H117, regardless of inoculum type, remained generally unchanged (P > 0.05) after aerobic storage (7 degrees C, 5 days) of untreated or HW/LA-treated beef samples previously stored in vacuum packages at 0 or 4 degrees C. However, reductions in E. coli O157:H7 levels were generally obtained when vacuum packaged, untreated beef samples previously stored at 12 degrees C were transitioned to aerobic conditions. Additionally, despite similar (P > 0.05) levels of E. coli O157:H7 cells of TSB, WASH, WETB, and DRYB origin on vacuum-packaged, untreated samples after 8 days of storage at 12 degrees C, subsequent aerobic storage resulted in larger (P < 0.05) reductions of cells of WETB and DRYB origin than for cells of TSB and WASH origin. For HW/LA-treated beef previously stored at 12 degrees C in vacuum packages, populations of E. coli O157:H7 remained largely unchanged after aerobic storage in retail packages. Results thus indicated that aerobic storage of beef (7 degees C, 5 days) previously stored in vacuum packages at 0 or 4 degrees C did not lead to E. coli O157:H7 population changes, whereas transition from vacuum packages stored under mildly abusive temperature (12 degrees C) to aerobic storage may have caused injury and death to the pathogen.

Detection of central nervous system tissue on meat and carcass-splitting band saw blade surfaces using modified fluorescent glial fibrillary acidic protein enzyme-linked immunosorbent assay sampling and extraction procedures.

This study was conducted to determine optimal buffer pH, extraction procedure, and temperature for detecting central nervous system (CNS) tissue on meat surfaces and on carcass-splitting band saw blades using swab sampling. Glial fibrillary acidic protein (GFAP) is restricted to CNS tissue and has been used as a marker for CNS tissue presence in meat products. Sample preparation, extraction procedure, and extraction temperature of glial fibrillary acidic protein fluorescent enzyme-linked immunosorbent assay (GFAP F-ELISA) were modified to detect CNS tissue on meat surfaces and on carcass-splitting band saw blades. Maximum GFAP recovery was observed with an extraction buffer pH of 7.4. Extracting samples at room temperature by vortexing for 30 s in 1 ml of extraction buffer (phosphate-buffered saline [pH 7.4] plus 0.05% sodium dodecyl sulfate) consistently provided detection of GFAP on meat surfaces contaminated with 500 microg of spinal cord suspension per 50 cm2 and on carcass-splitting band saw blades contaminated with 20 microg of spinal cord suspension per 50 cm2. Recovery of GFAP was not affected by storing samples overnight at 4 degrees C. The current studies demonstrate the effectiveness of modified sampling procedures and preparations, sample extraction buffer pH, and extraction temperatures. These modifications introduced to the original F-ELISA sampling protocol result in asensitive and repeatable assay for detection of CNS tissue on meat surfaces and on carcass-splitting band saw blades.

Comparison of immunochemical (enzyme-linked immunosorbent assay) and immunohistochemical methods for the detection of central nervous system tissue in meat products.

Three methods are widely used in the United States to detect the presence of central nervous system (CNS) tissue in meat products: the fluorescent enzyme-linked immunosorbent assay (F-ELISA), developed in this laboratory, the colorimetric Ridascreen Risk Material 10/5 ELISA (R-ELISA), and the U.S. Department of Agriculture, Food Safety and Inspection Service immunohistochemical (IHC) procedure. These assays are based on the immunological detection of glial fibrillary acidic protein (GFAP), a neural antigen largely restricted to the CNS. The objective of the current study was to compare the sensitivity and repeatability of these tests for detecting the presence of neural tissue in meat. Ground beef spiked with 0.05 to 0.5% of bovine brain, spinal cord (SC), or dorsal root ganglia, as well as advanced meat recovery samples, were evaluated by each of the three GFAP detection procedures. Interassay coefficients of variation for the F-ELISA GFAP standards were 7 to 25%, and intra-assay variation due to sampling and extraction of spiked ground beef was 7 to 13% for SC and 8 to 14% for brain (n = 10). The F-ELISA was the most sensitive of the methods tested, capable of detecting 0.3 ng GFAP standard per well and the presence of 0.05% brain and SC in meat. The R-ELISA standards produced highly variable results (up to 36% variation) and, as a result, none of these standards were different from zero (n = 26). The R-ELISA resulted in high sample variation in SC-spiked ground beef samples (coefficients of variation were 23 to 50%) and did not detect the presence of brain contamination. After modification of the R-ELISA sampling and extraction methods, SC-spiked sample variation was reduced to 16 to 20%, and sensitivity was improved from 0.3 to 0.2% SC, although brain tissue was still not detected. The IHC analysis of CNS-adulterated ground beef had a sensitivity of 0.2% SC and 0.05% brain, with false-negative rates of 10 to 20% at and above the stated sensitivities. None of the methods examined detected dorsal root ganglia contamination. The F-ELISA detected the presence of CNS contamination in 20% of the advanced meat recovery samples, compared to 3.5 to 5% for the R-ELISA and 2% for IHC. This study suggests that the F-ELISA is much more sensitive and repeatable than either the R-ELISA or the IHC procedure method for the detection of CNS tissue in meat products.

Postprocessing antimicrobial treatments to control Listeria monocytogenes in commercial vacuum-packaged bologna and ham stored at 10 degrees C.

The antilisterial effect of chemical dipping solutions on commercial bologna and ham slices, inoculated (3 to 4 log CFU/ cm2) after processing, was evaluated during storage in vacuum packages at 10 degrees C. Samples were inoculated with a 10-strain composite of Listeria monocytogenes and subsequently immersed (25+/-2 degrees C) for 2 min in 2.5% acetic acid (AA), 2.5% lactic acid (LA), 5% potassium benzoate (PB), or 0.5% Nisaplin (commercial form of nisin, equivalent to 5,000 IU/ml of nisin) solutions, either singly or sequentially (Nisaplin plus AA, Nisaplin plus LA, or Nisaplin plus PB), and then vacuum packaged and stored at 10 degrees C for 48 days. In addition to microbiological analysis, sensory evaluations were performed on uninoculated samples treated with AA, LA, or PB. Initial reductions (day 0) of the pathogen, compared with the controls, on bologna and ham samples treated with AA, LA, or PB ranged from 0.4 to 0.7 log CFU/cm2. Higher (P < 0.05) initial reductions (2.4 to 2.9 log CFU/cm2) were obtained for samples treated with Nisaplin alone and when followed by AA, LA, or PB. L. monocytogenes populations on control bologna and ham samples increased from 3.4 log CFU/cm2 (day 0) to 7.4 and 7.8 log CFU/ cm2, respectively, in 8 days at 10 degrees C. Listericidal effects were observed for all treatments tested, except for Nisaplin applied on its own, during storage at 10 degrees C. The sequential treatment of Nisaplin plus LA reduced L. monocytogenes to undetectable levels in both products at the end of storage. The sequential treatments were also found to inhibit growth of spoilage microorganisms. Sensory evaluations indicated that dipping (2 min) of ham samples in AA (2.5%), LA (2.5%), or PB (5%) led to lower sensory scores. However, since results of this study indicated that these treatments caused extensive listericidal effects, there is possibly a potential to reduce the levels of chemicals applied and still achieve adequate antilisterial activity without major negative effects on product quality.

Effect of single or sequential hot water and lactic acid decontamination treatments on the survival and growth of listeria monocytogenes and spoilage microflora during aerobic storage of fresh beef at 4, 10, and 25 degrees C.

The survival and growth of Listeria monocytogenes and spoilage microflora during storage of fresh beef subjected to different decontamination treatments was studied. Fresh beef inoculated with a five-strain mixture of L. monocytogenes (5.18 log CFU/cm2) was left untreated (control) or was immersed (30 s) in hot water (HW; 75 degrees C), 2% lactic acid (LA; 55 degrees C), hot water followed by lactic acid (HW-LA), or lactic acid followed by hot water (LA-HW) and then stored aerobically at 4, 10, and 25 degrees C for 25, 17, and 5 days, respectively. Initial populations of L. monocytogenes were reduced by 0.82 (HW), 1.43 (LA), 2.73 (HW-LA), and 2.68 (LA-HW) log CFU/cm2. During storage, the pathogen grew at higher rates in HW than in control samples at all storage temperatures. Acid decontamination treatments (LA. HW-LA, and LA-HW) resulted in a weaker inhibition of L. monocytogenes (P < 0.05) at 25 degrees C than at 4 and 10 degrees C. In general, the order of effectiveness of treatments was HW-LA > LA > LA-HW > HW > control at all storage temperatures tested. In untreated samples, the spoilage microflora was dominated by pseudomonads, while lactic acid bacteria, Enterobacteriaceae, and yeasts remained at lower concentrations during storage. Brochothrix thermosphacta was detected periodically in only a limited number of samples. Although decontamination with HW did not affect the above spoilage microbial profile, acid treatments shifted the predominant microflora in the direction of yeasts and gram-positive bacteria (lactic acid bacteria). Overall, the results of the present study indicate that decontamination with LA and combinations of LA and HW could limit growth of L. monocytogenes and inhibit pseudomonads, which are the main spoilage bacteria of fresh beef stored under aerobic conditions. However, to optimize the efficacy of such treatments, they must be applied in the appropriate sequence and followed by effective temperature control.

Control of Listeria monocytogenes with combined antimicrobials after postprocess contamination and extended storage of frankfurters at 4 degrees C in vacuum packages.

Contamination of ready-to-eat foods, such as frankfurters, with Listeria monocytogenes, is a major concern that needs to be addressed in order to enhance the safety of these products. The objective of this study was to determine the effectiveness of combinations of antimicrobials included in the formulation of frankfurters against L. monocytogenes inoculated (10(3) to 10(4) CFU/cm2) on their surface after peeling and before vacuum packaging. In addition, the antilisterial effect of immersing the packaged products, prepared with or without antimicrobials, in hot (75 or 80 degrees C) water for 30 to 90 s was evaluated. Samples were stored at 4 degrees C for up to 120 days and periodically analyzed for pH and for microbial growth on tryptic soy agar plus 0.6% yeast extract (TSAYE) and PALCAM agar. Sodium lactate (1.8%; 3% of a 60% commercial solution) used alone inhibited growth of L. monocytogenes for 35 to 50 days, whereas when used in combination with 0.25% sodium acetate, sodium diacetate, or glucono-delta-lactone (GDL), sodium lactate inhibited growth throughout storage (120 days). Immersing packaged frankfurters in hot water (80 degrees C, 60 s) reduced inoculated populations of L. monocytogenes by 0.4 to 0.9 log CFU/cm2 and reduced its growth by 1.1 to 1.4 log CFU/cm2 at 50 to 70 days of storage in samples containing 1.8% sodium lactate alone. However, immersion of frankfurters containing no antimicrobials in hot water (75 or 80 degrees C) did not inhibit growth of the pathogen for more than 10 to 20 days, unless one frankfurter was placed per bag and heat treated for 90 s. These results indicate that the inclusion of 1.8% sodium lactate with 0.25% sodium acetate, sodium diacetate, or GDL in cured meat formulations may control L. monocytogenes growth during refrigerated (4 degrees C) storage. Additional studies are required to evaluate the effects of these combinations at abusive temperatures of storage, as well as on additional processed meat formulations and on the sensory quality and shelf life of products.