Commercial Beef Processing Plant Research Articles

Use of overlapping DNA pools to discern genetic differences despite pooling error.

Genotyping pools of commercial cattle and individual seedstock animals may reveal hidden relationships between sectors enabling use of commercial data for genetic evaluation. However, commercial data capture may be compromised by inexact pool formation. We aimed to estimate the concordance between distances or genomic covariance among pooling allele frequencies (PAFs) of DNA pools comprised of 100 animals with 0% or 50% overlap of animals in common between pools. Cattle lung samples were collected from a commercial beef processing plant on a single day. Six pools of 100 animals each were constructed so that overlap between pools was 0% or 50%. Two pools of all 200 animals were constructed to estimate PAFs for all 200 animals. Frozen lung tissue (0.01 g) from each animal was weighed into a tube containing a pool; there were two pools of 200 animals each and six pools of 100 animals each. Every contribution of an individual animal was an independent measurement to insure independence of pooling errors. Lung samples were kept on dried ice during the pooling process to keep them from thawing. The eight pools were then assayed for approximately 100,000 single nucleotide polymorphisms (SNP). PAF for each SNP and pool was based on the relative intensity of the two dyes used to detect the alleles rather than genotype calls which are not tractable from pooling data. Euclidean distances and genomic relationships among the PAFs for the eight pools were estimated and distances were tested for concordance with pool overlap using permutation-based analysis of distance. Distances among pools were concordant with the planned overlap of animals shared between pools (P = 0.0024); pool overlap accounted for 70% of the variation and pooling error accounted for 30%. Pools containing 100 animals with no overlap were the most distant from one another and pools with 50% overlap were the least distant. This work shows that we can discern differences in distance between pairs of overlapping DNA pools sharing 0% and 50% of the animals. Genomic correlations among nonoverlapping pools indicated that nonoverlapping pool pairs did not share many related animals because genomic correlations were near zero for these pairs. On the other hand, one pair of nonoverlapping pools likely contained related animals between pools because the correlation was 0.21. Pools sharing 50% overlap ranged in genomic relationship between 0.21 and 0.39 (N = 12).

In-Plant Intervention Validation of a Novel Ozone Generation Technology (Bio-Safe) Compared to Lactic Acid in Variety Meats.

The objective of this experiment was to compare the antimicrobial efficacy of an aqueous ozone intervention and a lactic acid solution on natural microbiota of variety meats in a commercial beef processing plant. EZ-Reach™ swabs were used to collect 100 cm2 area samples before and after ozone and lactic acid intervention application for three different offals (head, heart, and liver). Each repetition included 54 samples per variety meat and antimicrobial for a total of 162 samples per repetition. Enumeration of total aerobic bacteria (APC) and Escherichia coli (EC) was performed on each sample. Microbial counts for both microorganisms evaluated were significantly reduced (p < 0.001) after lactic acid immersion (2–5%) and ozone intervention for all variety meats, with the exception of ozone intervention in EC counts of the heart samples. APC after lactic acid intervention was reduced on average by 1.73, 1.66, and 1.50 Log CFU/sample in the head, heart, and liver, respectively, while after ozone intervention, counts were reduced on average by 1.66, 0.52, and 1.20 Log CFU/sample. EC counts after lactic acid intervention were reduced on average by 0.96, 0.79, and 1.00 Log CFU/sample in the head, heart, and liver, respectively, while after ozone intervention, counts were reduced on average by 0.75, 0.62, and 1.25 Log CFU/sample. The aqueous ozone antimicrobial scheme proved to be a promising intervention for the in-plant reduction of indicator levels in variety meats, specifically heads, hearts, and livers.

Variations in Low Electrical Stimulator Voltage Settings Minimally Influence Beef Longissimus Muscle Slice Shear Force Values

The objective of the current study was to evaluate the effect of differing electrical stimulation (ES) voltage levels on beef longissimus muscle tenderness, postmortem temperature, pH decline, and carcass quality. Beef carcasses from 3 commercial beef processing plants (A, B, C) were exposed to 3 varying voltage levels: (1) control (no ES), (2) ES level 1 (ES1; 60 Hz for 17 s each at 16, 20, 24, and 28 V), and (3) ES level 2 (ES2; 60 Hz for 17 s each at 25, 35, 45, and 55 V) prior to chilling. Ninety beef carcasses were selected from each of the 3 plants, and within a carcass, paired sides were randomly assigned to one of 3 ES treatments (n = 60 sides/treatment/plant). The results indicated that ES affected (P &amp;lt; 0.05) muscle pH at 3 h postmortem in 2 of the 3 plants. However, ES did not affect (P &amp;gt; 0.05) pH at the time of grading (postrigor). Although the slice shear force (SSF) values were lower (P &amp;lt; 0.05) for ES steaks compared with controls, voltage did not affect (P &amp;gt; 0.05) SSF values. Variation in SSF was observed among the plants (P &amp;lt; 0.05), with steaks from Plant C having greater (P &amp;lt; 0.05) SSF values compared with steaks from Plants A and B, which exhibited similar (P &amp;gt; 0.05) SSF values. Overall, although ES steaks had lower SSF values compared with control steaks, the lack of difference in postmortem tenderness between ES1 and ES2 voltage settings indicated that the low ES voltages minimally influenced SSF values.

In-Plant Validation of Novel On-Site Ozone Generation Technology (Bio-Safe) Compared to Lactic Acid Beef Carcasses and Trim Using Natural Microbiota and Salmonella and E. coli O157:H7 Surrogate Enumeration.

The purpose of this study was to evaluate the antimicrobial efficacy of an aqueous ozone (Bio-Safe) treatment and lactic acid solutions on natural microbiota and E. coli O157:H7 and Salmonella surrogates on beef carcasses and trim in a commercial beef processing plant. For every repetition, 40 carcass and 40 trim swabs (500 cm2) were collected. Samples were taken using EZ-ReachTM swabs, and plated into aerobic plate count (APC), coliform, and E. coli PetrifilmTM for enumeration. In addition, a five-strain cocktail (MP-26) of E. coli surrogates was inoculated onto trim. For every trim surrogate repetition, 30 trim pieces were sampled after attachment and after ozone intervention. Samples were diluted and counts were determined using the TEMPO® system for E. coli enumeration. Ozone and lactic acid interventions significantly reduced (p < 0.003) bacterial counts in carcasses and trim samples. Moreover, lactic acid further reduced APC and coliforms in trim samples compared to ozone intervention (p < 0.009). In the surrogate trials, ozone significantly reduced (p < 0.001) surrogate concentration. Historical data from the plant revealed a reduction (p < 0.001) of presumptive E. coli O157:H7 in trim after a full year of ozone intervention implementation. The novel technology for ozone generation and application as an antimicrobial can become an alternative option that may also act synergistically with existing interventions, minimizing the risk of pathogens such as Salmonella and E. coli O157:H7.

Validation of Additional Approaches and Applications for Using the Continuous and Manual Sampling Devices for Raw Beef Trim

In this work, the goal was to determine the efficacy of MicroTally-based sampling in scenarios commonly encountered in the commercial beef processing industry, but outside of the parameters evaluated during the initial proof-of-concept work. The data were derived from 1,650 matched samples collected from 540 individual combo bins at six commercial beef processing plants, comparing MicroTally-based sampling (continuous and manual sampling devices [CSD and MSD]) to N60 Excision and/or N60 Plus methods. Mounting a 61-cm CSD cartridge to a 30-cm-wide conveyor provided sampling that is equivalent to N60 Excision and N60 Plus methods. Mounting a CSD to a chute instead of a conveyor was equivalent to the N60 Plus sampling method. The CSD was shown to be effective for sampling when used in conjunction with a "swinging arm trim diverter" and receiving product in batch mode as opposed to continuous flow. MSD sampling of oval combo bins with trim surface area (≈0.93 m2 [≈1,439 in2]) less than 1 m2 (1,600 in2) was shown to be equivalent to the N60 Plus sample collection method. Peracetic acid applied at the end of the trim conveyor did not negatively impact pathogen index target detection of the CSD even if the samples were shipped overnight before analysis. Pathogen index targets were demonstrated to be useful tools for validating methods designed to measure pathogen prevalence. The data presented herein support equivalency criteria of within 0.5 log CFU per sample for indicator organism counts. These data collectively support various alternative applications of MicroTally-based trim sampling and the application and interpretation of alternative methods for pathogen detection.

Investigating the Etiology of Sour Knuckles in Postchilled Beef Carcasses

Development of sourness in beef round muscle cuts, such as knuckles, has been a long-standing issue in the beef industry with little characterization. Therefore, the objective of this study was to investigate and characterize the sour odor associated with beef knuckles using sensory, analytical (gas chromatography-mass spectrometry [GC-MS]), and microbiological approaches. Knuckles (n = 10) with no sour odor (control), a slight sour odor, or severe sour odor were collected during fabrication from a commercial beef processing plant. In addition, the synovial fluid from the femur joint, and the femur surface associated with the collected knuckles, were sponge-sampled. Knuckles were separated into 2 halves, with one half subjected to an odor panel, GC-MS, and microbial analyses on the day of collection (day 0). The remaining half was analyzed for odor and microbial populations following 35 d of vacuum-packaged storage at 0°C ± 2°C (day 35). Odor panelists identified differences (P &amp;lt; 0.05) between control and sour knuckles (slight sour odor and severe sour odor) for all attributes tested (off-odor, oxidation, putrid, and sour notes) regardless of storage day. GC-MS analysis found no statistical difference (P &amp;gt; 0.05) in volatiles between control and severe-sour-odor samples. Microbial analysis (aerobic plate counts and lactic acid bacteria counts) of muscle tissue on day 0 and day 35 of storage revealed no (P &amp;gt; 0.05) differences between the 3 treatment groups. Similarly, no (P &amp;gt; 0.05) differences between the treatment groups were obtained following analysis of synovial fluid and femur surface sponge samples for psychrotrophic anaerobic sporeformer counts. The findings of the study indicated that the souring condition in knuckles exists at identifiable intensities with no volatile acid or microbial population differences; therefore, further investigation is needed to determine the etiology.

110 Metmyoglobin reducing activity and oxygen consumption properties of atypical dark-cutting beef

Abstract Deviation from characteristic bright-red color during grading leads to discounted carcass price and value. Dark-cutting carcasses are examples of color deviation due to high-pH. However, atypical dark-cutters are not discounted at grading but have a dark color compared to normal-pH beef. Limited knowledge is currently available on the biochemical properties of atypical dark cutting beef compared with normal-pH beef. Therefore, the objective of the study was to determine metmyoglobin reducing activity and oxygen consumption of atypical dark-cutting beef. Strip loins from atypical dark-cutting (ADC; selected based on HunterLab L* values and pH less than 5.8 and not discounted by grader) and USDA Low Choice (C) carcasses were selected from a commercial beef processing plant and transported to the Food and Agricultural Products Center in Stillwater, Oklahoma. pH, color, oxygen consumption, and metmyoglobin reducing activity of atypical dark cutters and normal pH loins were determined on d3 postmortem. The surface color was determined using a HunterLab Miniscan spectrophotometer. Reflectance-based methods using K/S ratios were utilized to determine oxygen consumption and metmyoglobin reducing activity. The data were analyzed using the Mixed Procedure of SAS and the experiment was replicated 10 times (n = 10). There were no differences in initial pH (C = 5.46 and ADC = 5.6 atypical dark-cutter; P = 0.05) between normal-pH and atypical dark cutters. However, atypical dark cutters had lower lightness (L* values; C = 44.2 and ADC = 38.4), redness (a* values; C = 28.6 and ADC = 25.2), and red intensity (chroma; C = 40.2 and ADC = 36.4) compared with normal-pH. Further, atypical dark cutters had greater (P &amp;lt; 0.05) oxygen consumption and metmyoglobin reducing activity than normal-pH. The results suggest that atypical dark cutters and normal-pH beef have different biochemical properties.

The Effect of Modified Atmospheric Packaging on Beef Color Sensory Characteristics of Different Muscle pH Categories

ObjectivesAny deviation from the bright-red color of beef can lead to discounted price or consumer rejection. Fresh beef lean color is influenced by pH. Various packaging techniques have been developed to enhance the lean color of beef steaks. Therefore, the objective of the current study was to evaluate the effects of modified atmospheric packaging on three different beef muscle pH categories.Materials and MethodsThe three categories evaluated for this study were: Normal (pH = 5.57 ± 0.1; N-pH), Moderately high (pH = 5.70 ± 0.09; M-pH), and High (pH = 6.39 ± 0.03; H-pH). The pH was taken on the carcass, at the 12th and 13th rib interface within 72 h of harvest at a commercial beef processing plant. Strip loins were fabricated from each carcass (n = 12) and sent to Oklahoma State University for further analysis. Strip loins were then cut into 2.54 cm steaks and randomly assigned to 1 of 3 packaging treatments: polyvinyl chloride overwrap (PVC), carbon monoxide modified atmosphere packaging (CO-MAP; 0.4% CO, 69.6% N, and 30% CO2) and high-oxygen modified atmospheric packaging (HiOx-MAP; 80% O2, and 20% CO2). Visual color measurements for muscle color (MC; (1 = extremely bright cherry-red and 7 = extremely dark red), and surface discoloration (SD; 1 = no discoloration [0%] and 7 = extensive discoloration [81–100%]) were recorded on d 2, 4, and 6 of retail display by a trained panel. Data were analyzed using the Mixed Procedure of SAS.ResultsFor all pH treatments, PVC packaging possessed the darkest muscle color (P &lt; 0.05) score compared to CO- and HiOx-MAP. When comparing N-pH, M-pH, and H-pH values, CO-MAP had approximately a 27.3%, 22.2%, and 25.3% improvement in muscle color, indicating a brighter lean color compared to PVC. Additionally, HiOx-MAP had approximately a 10.9%, 17.4%, and 16.5% improvement in muscle color score for N-pH, M-pH, and H-pH, respectively. When packaging steaks in either CO- or HiOx-MAP there was no significant difference (P &gt; 0.05) between d 4 and 6 of retail display for muscle color. However, there was a significant (P &lt; 0.05) darkening in muscle color for steaks packaged in PVC from d 4 to 6 of retail display. By the fourth d of retail, N-pH steaks packaged in PVC had 38.3% and 39.0% greater (P &lt; 0.05) surface discoloration than CO- and HiOx-MAP, respectively.ConclusionThese results suggest that packaging steaks of different pH categories in CO- or HiOx-MAP can improve the surface color compared to PVC packaging.

Modified Atmospheric Packaging and Antioxidant Enhancement Improves Redness of Atypical Dark-Cutting Beef

ObjectivesDark-cutting carcasses occur when muscle pH does not decrease sufficiently during rigor mortis because of antemortem glycogen depletion. Typical dark-cutting beef have a pH &gt; 6.0, however, atypical dark-cutting (ADC) beef have a pH around 5.7- 5.9 but have a darker lean color similar to dark-cutting beef. Previous studies noted that greater muscle pH in dark-cutting beef increase oxygen consumption and decrease myoglobin oxygenation. However, limited research has determined the biochemical basis of ADC. Therefore, the objectives of this study were to characterize the biochemical basis of ADC beef carcasses and to utilize modified atmosphere packaging (MAP) and rosemary enhancement to improve appearance during retail display.Materials and MethodsStrip loins from ADC and USDA Low Choice (C) carcasses were selected from a commercial beef processing plant and transported to the Food and Agricultural Products Center in Stillwater, OK. Control (C) and ADC steaks (prior to enhancement and packaging) were utilized to measure pH, color, oxygen consumption, and proximate compositions. Loin sections were cut into halves and randomly assigned to combinations of packaging types and enhancement treatment. Packaging included high-oxygen MAP (HiOx-MAP; 80% oxygen and 20% carbon dioxide), carbon monoxide MAP (CO-MAP; 0.4% CO, 69.6% N, and 30% CO2), and PVC. Enhancement includes 0.1% rosemary oleoresin pumped to 10% of loin green weights. Following enhancement and packaging, steaks were displayed under retail conditions for 6 d to measure color changes using a HunterLab spectrophotometer. The data were analyzed using the Mixed Procedure of SAS, and the experiment was replicated 13 times (n = 13).ResultsThere were no differences for initial pH or proximate compositions (P &lt; 0.05) between C and ADC. However, ADC had lower initial lightness (L* values), redness (a* values), and red intensity (chroma) compared with C. Further, ADC had greater (P &lt; 0.05) oxygen consumption than C. There was a significant packaging × enhancement × display time interaction resulted for L*, a*, and chroma. CO-MAP and HiOx-MAP in combination with rosemary enhancement improved (P &lt; 0.05) redness of ADC by 61.7% and 42.3%, respectively, compared with ADC in PVC packaging. Similarly, MAP and enhancement improved lightness (L* values) and chroma compared with ADC in PVC. By Day 6 of display, enhanced ADC steaks packaged in both HiOx-MAP and CO-MAP had similar color parameters to control choice steaks; however, non-enhanced ADC steaks had significantly lower a* (P &lt; 0.0001) and chroma (P &lt; 0.01) values when packaged in HiOx-MAP when compared to both C and enhanced ADC.ConclusionThe results suggest that ADC beef has greater oxygen consumption than C steaks even at similar muscle pH. Use of modified atmospheric packaging in combination with enhancement has the potential to improve surface color of ADC beef.

Investigating the Etiology of Increased Incidence of Sour Knuckles in Commercial Beef Processing Facilities

ObjectivesCattle weights have increased during the last couple of decades and have not always been accompanied by improvements in facility capabilities and management. Alongside quality issues of color, tenderness, and water holding capacity, issues such as sour muscles and bone taints are now appearing with great frequency in the meat industry. Development of off-flavor/sourness in deep muscles such as knuckles (vastus femoris, vastus lateralis, vastus medialis, and rectus femoris) has been a long-standing issue in the beef industry, however, has not been well characterized. Therefore, the objective of this study was to investigate the cause, and characterize sour odor associated with beef knuckles using microbial, odor panel, and gas chromatography-mass spectrometric (GC–MS) analyses.Materials and MethodsKnuckles (n = 10) identified as having no sour odor (control), slight odor, or severe odor were collected from the fabrication line of a commercial beef processing plant. Sponge samples of synovial fluid and femur surface of the round were also obtained at the time of collection, for determination of anaerobic sporeformer counts. The collected knuckles were transported on ice to the laboratory where they were aseptically separated into two halves, with one half destined for microbial, odor, and GC–MS analyses on the day of collection (Day 0) and the other half for the same analyses after 35 d of vacuum packaged storage at 2°C (Day 35). For microbial analysis, 15 g of tissue was excised from the muscle surface and was analyzed for aerobic plate counts (Petrifilm Aerobic Count plates) and lactic acid bacteria counts (Lactobacilli MRS agar). Samples (5 g) for GC–MS were held at –80°C until analysis. The remainder of the sample was diced and used for trained odor panels. Data were analyzed using the ANOVA function in R (v. 3.5.1.), with a significance level of α = 0.05. Upon finding significant differences (P &lt; 0.05) the means function was used to determine differences between groups.ResultsIrrespective of sourness classification of the knuckles, similar (P &gt; 0.05) anaerobic sporeformer counts were obtained for the synovial fluid and femur surface. Additionally, muscle tissue samples from control, slightly sour and severely sour knuckles had similar (P &gt; 0.05) aerobic plate counts and lactic acid bacteria counts. Odor panelists identified differences (P &lt; 0.05) for all attributes between control and sour knuckles (slight and severe) on Day 0. Similarly, on Day 35, differences (P &lt; 0.05) were observed between control, slightly sour, and severely sour knuckles for all attributes, with severe receiving the highest score for all categories. GC–MS results showed no differences (P &gt; 0.05) between control and sour knuckles for propionic, butyric, isobutyric, and acetonic acid.ConclusionMicrobiological analysis found no differences in culturable organisms between control, slight, and severely sour knuckles on Day 0 or Day 35. However, odor panelists were able to identify differences between control and sour knuckles even after 35 d in vacuum packaging. GC–MS analysis did not indicate a statistical difference in the abundance of volatiles between the treatments, probably due to high variations within treatment groups.

Draft Genome Sequences of 43 Enterococcus faecalis and Enterococcus faecium Isolates from a Commercial Beef Processing Plant and Retail Ground Beef.

Here, we report the draft genome sequences of 36 Enterococcus faecalis and 7 Enterococcus faecium isolates recovered from a beef processing facility and retail ground beef. The beef processing facility samples were collected from beef carcasses, conveyor belts, and ground product.

The Effect of Modified Atmospheric Packaging on Beef Color Sensory Characteristics of Different Muscle pH Categories

ObjectivesAny deviation from the bright-red color of beef can lead to discounted price or consumer rejection. Fresh beef lean color is influenced by pH. Various packaging techniques have been developed to enhance the lean color of beef steaks. Therefore, the objective of the current study was to evaluate the effects of modified atmospheric packaging on three different beef muscle pH categories.Materials and MethodsThe three categories evaluated for this study were: Normal (pH = 5.57 ± 0.1; N-pH), Moderately high (pH = 5.70 ± 0.09; M-pH), and High (pH = 6.39 ± 0.03; H-pH). The pH was taken on the carcass, at the 12th and 13th rib interface within 72 h of harvest at a commercial beef processing plant. Strip loins were fabricated from each carcass (n = 12) and sent to Oklahoma State University for further analysis. Strip loins were then cut into 2.54 cm steaks and randomly assigned to 1 of 3 packaging treatments: polyvinyl chloride overwrap (PVC), carbon monoxide modified atmosphere packaging (CO-MAP; 0.4% CO, 69.6% N, and 30% CO2) and high-oxygen modified atmospheric packaging (HiOx-MAP; 80% O2, and 20% CO2). Visual color measurements for muscle color (MC; (1 = extremely bright cherry-red and 7 = extremely dark red), and surface discoloration (SD; 1 = no discoloration [0%] and 7 = extensive discoloration [81–100%]) were recorded on d 2, 4, and 6 of retail display by a trained panel. Data were analyzed using the Mixed Procedure of SAS.ResultsFor all pH treatments, PVC packaging possessed the darkest muscle color (P < 0.05) score compared to CO- and HiOx-MAP. When comparing N-pH, M-pH, and H-pH values, CO-MAP had approximately a 27.3%, 22.2%, and 25.3% improvement in muscle color, indicating a brighter lean color compared to PVC. Additionally, HiOx-MAP had approximately a 10.9%, 17.4%, and 16.5% improvement in muscle color score for N-pH, M-pH, and H-pH, respectively. When packaging steaks in either CO- or HiOx-MAP there was no significant difference (P > 0.05) between d 4 and 6 of retail display for muscle color. However, there was a significant (P < 0.05) darkening in muscle color for steaks packaged in PVC from d 4 to 6 of retail display. By the fourth d of retail, N-pH steaks packaged in PVC had 38.3% and 39.0% greater (P < 0.05) surface discoloration than CO- and HiOx-MAP, respectively.ConclusionThese results suggest that packaging steaks of different pH categories in CO- or HiOx-MAP can improve the surface color compared to PVC packaging.

Modified Atmospheric Packaging and Antioxidant Enhancement Improves Redness of Atypical Dark-Cutting Beef

ObjectivesDark-cutting carcasses occur when muscle pH does not decrease sufficiently during rigor mortis because of antemortem glycogen depletion. Typical dark-cutting beef have a pH > 6.0, however, atypical dark-cutting (ADC) beef have a pH around 5.7- 5.9 but have a darker lean color similar to dark-cutting beef. Previous studies noted that greater muscle pH in dark-cutting beef increase oxygen consumption and decrease myoglobin oxygenation. However, limited research has determined the biochemical basis of ADC. Therefore, the objectives of this study were to characterize the biochemical basis of ADC beef carcasses and to utilize modified atmosphere packaging (MAP) and rosemary enhancement to improve appearance during retail display.Materials and MethodsStrip loins from ADC and USDA Low Choice (C) carcasses were selected from a commercial beef processing plant and transported to the Food and Agricultural Products Center in Stillwater, OK. Control (C) and ADC steaks (prior to enhancement and packaging) were utilized to measure pH, color, oxygen consumption, and proximate compositions. Loin sections were cut into halves and randomly assigned to combinations of packaging types and enhancement treatment. Packaging included high-oxygen MAP (HiOx-MAP; 80% oxygen and 20% carbon dioxide), carbon monoxide MAP (CO-MAP; 0.4% CO, 69.6% N, and 30% CO2), and PVC. Enhancement includes 0.1% rosemary oleoresin pumped to 10% of loin green weights. Following enhancement and packaging, steaks were displayed under retail conditions for 6 d to measure color changes using a HunterLab spectrophotometer. The data were analyzed using the Mixed Procedure of SAS, and the experiment was replicated 13 times (n = 13).ResultsThere were no differences for initial pH or proximate compositions (P < 0.05) between C and ADC. However, ADC had lower initial lightness (L* values), redness (a* values), and red intensity (chroma) compared with C. Further, ADC had greater (P < 0.05) oxygen consumption than C. There was a significant packaging × enhancement × display time interaction resulted for L*, a*, and chroma. CO-MAP and HiOx-MAP in combination with rosemary enhancement improved (P < 0.05) redness of ADC by 61.7% and 42.3%, respectively, compared with ADC in PVC packaging. Similarly, MAP and enhancement improved lightness (L* values) and chroma compared with ADC in PVC. By Day 6 of display, enhanced ADC steaks packaged in both HiOx-MAP and CO-MAP had similar color parameters to control choice steaks; however, non-enhanced ADC steaks had significantly lower a* (P < 0.0001) and chroma (P < 0.01) values when packaged in HiOx-MAP when compared to both C and enhanced ADC.ConclusionThe results suggest that ADC beef has greater oxygen consumption than C steaks even at similar muscle pH. Use of modified atmospheric packaging in combination with enhancement has the potential to improve surface color of ADC beef.

Comparison of the Efficacy of a Sulfuric Acid–Sodium Sulfate Blend and Lactic Acid for the Reduction of Salmonella on Prerigor Beef Carcass Surface Tissue

A study was conducted to compare the efficacy of a commercially available sulfuric acid-sodium sulfate blend (SSS) and lactic acid (LA) in reducing inoculated Salmonella populations on beef. Sixty pieces of prerigor beef carcass surface brisket tissue, collected directly from the processing line of a commercial beef processing plant, were cut into two sections (10 by 10 cm each) and spot inoculated (6 to 7 log CFU/cm2) on the adipose side with a six-strain mixture of Salmonella. One section per piece of brisket tissue was left untreated (control), while the second section was spray treated (5 s, 15 lb/in2, and 33 mL/s flow rate) with unheated (21°C) or heated (52°C) solutions of SSS (pH 1.1) or LA (4%). Unheated and heated SSS lowered (P < 0.05) total bacterial counts from 6.3 to 4.6 and 4.3 log CFU/cm2, respectively. Likewise, unheated and heated LA reduced (P < 0.05) total bacterial counts from 6.3 to 4.7 and 4.4 log CFU/cm2, respectively. Initial counts of inoculated Salmonella populations (6.1 to 6.2 log CFU/cm2) were reduced (P < 0.05) to 4.2 and 3.9 log CFU/cm2 following treatment with unheated and heated SSS, respectively, and to 3.7 and 3.8 log CFU/cm2 after treatment with unheated and heated LA, respectively. Overall, the temperature of the chemical solutions had a small (0.3 log CFU/cm2), but significant (P < 0.05), effect on total bacterial counts but not (P > 0.05) on Salmonella counts. Regardless of solution temperature, Salmonella counts for LA-treated samples were 0.3 log CFU/cm2 lower (P < 0.05) than those of samples treated with SSS. These results indicate that both unheated and heated solutions of SSS and LA are effective interventions for reducing Salmonella contamination on prerigor beef carcass surface tissue.

Evaluation of Bacteriophage Application to Cattle in Lairage at Beef Processing Plants to Reduce Escherichia coli O157:H7 Prevalence on Hides and Carcasses.

Escherichia coli O157:H7 is a major food safety concern for the beef industry. Several studies have provided evidence that cattle hides are the main source of beef carcass contamination during processing and that reductions in the E. coli O157:H7 load on the hides of cattle entering processing facilities will lead to reductions in carcass contamination. Bacteriophages have been proposed as a novel preharvest antimicrobial intervention to reduce the levels of E. coli O157:H7 on cattle hides. The objective of this study was to evaluate a commercialized phage application administered in the lairage area of commercial beef processing plants for the ability to reduce E. coli O157:H7 contamination of cattle hides and carcasses. Cattle lots either received phage spray treatment (n = 289) or did not (n = 301), as they entered the lairage environments in two separate experiments at two different commercial beef processing plants. Hide and carcass samples were collected and analyzed for E. coli O157:H7 prevalence and concentration. Cattle hides receiving phage treatment had an E. coli O157:H7 prevalence of 51.8%, whereas untreated hides had a prevalence of 57.6%. For carcass samples, the E. coli O157 prevalence in treated and untreated samples was 17.1% and 17.6%, respectively. The results obtained from these experiments demonstrated that the treatment of cattle hides with bacteriophages before processing did not produce a significant reduction of E. coli O157:H7 on cattle hides or beef carcasses during processing.

Genomewide association study of lung lesions in cattle using sample pooling.

Bovine respiratory disease complex (BRDC) is the most expensive disease in beef cattle in the United States costing the industry at least US$1 billion annually. Bovine respiratory disease complex causes damage to lung tissue resulting in persistent lung lesions observable at slaughter. Severe lung lesions at harvest have been associated with decreased preharvest ADG and increased clinical BRDC in the feedlot. Our objective was to identify SNP that are associated with severe lung lesions observed at harvest in feedlot cattle. We conducted a genomewide association study (GWAS) using a case-control design for severe lung lesions in fed cattle at slaughter using the Illumina Bovine HD array (approximately 770,000 SNP) and sample pooling. Lung samples were collected from 11,520 young cattle, a portion of which had not been treated with antibiotics (participating in a "natural" marketing program), at a large, commercial beef processing plant in central Nebraska. Lung samples with lesions (cases) and healthy lungs (controls) were collected when both phenotypes were in close proximity on the viscera (offal) table. We constructed 60 case and 60 control pools with 96 animals per pool. Pools were constructed by sampling sequence to ensure that case and control pool pairs were matched by proximity on the processing line. The Bovine HD array (770,000 SNP) was run on all pools. Fourteen SNP on BTA 2, 3, 4, 9, 11, 14, 15, 22, 24, and 25 were significant at the genomewide experiment-wise error rate of 5% ( ≤ 1.49 × 10). Eighty-five SNP on 28 chromosomes achieved a false discovery rate of 5% ( ≤ 5.38 × 10). Significant SNP were near (±100 kb) genes involved in tissue repair and regeneration, tumor suppression, cell proliferation, apoptosis, control of organ size, and immunity. Based on 85 significantly associated SNP in or near a collection of genes with diverse function on 28 chromosomes, we conclude that the genomic footprint of lung lesions is complex. A complex genomic footprint (genes and regulatory elements that affect the trait) is consistent with what is known about the cause of the disease: complex interactions among multiple viral and bacterial pathogens along with several environmental factors including dust, commingling, transportation, and stress. Characterization of sequence variation near significant SNP will enable accurate and cost effective genome-enhanced genetic evaluations for BRDC resistance in AI bulls and seed stock populations.

Microbial assessment of an upward and downward dehiding technique in a commercial beef processing plant

Preventing microbial contamination during dehiding is challenging, and skinning methods are of critical importance for the hygienic status of beef carcasses. Two skinning methods are usually employed: upward hide pulling (UHP) and downward hide pulling (DHP). This study has compared the microbiological contamination of carcasses using both systems in a beef processing plant in the process of changing its dehiding method from UHP to DHP. 100cm2 areas from eight carcass sites (ham, chuck, rump, bung, flank, brisket, shin and neck) were sampled on 36 skinned carcasses dehided by each technique. Total viable counts (TVCs) and Enterobacteriaceae counts for each site were determined. No significant differences were observed in total (pooled-samples) carcass contamination regardless of the method used. However, significant differences (p<0.05) in TVCs were observed at the flank, shin, brisket and neck. These differences can be attributed to possible deficiencies in the implementation of the HACCP pre-requisite programmes, and are not necessarily associated with the skinning method per se.

Detection of Escherichia coli O157:H7 and Salmonella enterica in air and droplets at three U.S. commercial beef processing plants.

Bacteria are known to be present in the air at beef processing plants, but published data regarding the prevalences of airborne Escherichia coli O157:H7 and Salmonella enterica are very limited. To determine if airborne pathogens were present in beef processing facilities, we placed sedimentation sponges at various locations in three commercial beef plants that processed cattle from slaughter through fabrication. For the 291 slaughter area air samples, E. coli O157:H7 was isolated from 15.8% and S. enterica from 16.5%. Of the 113 evisceration area air samples, E. coli O157:H7 was isolated from only one sample and S. enterica was not isolated from any sample. Pathogens were not isolated from any of the 87 air samples from fabrication areas. Pathogen prevalences, aerobic plate counts, and Enterobacteriaceae counts were highest for air samples obtained from locations near hide removal operations. The process of hide removal disperses liquid droplets, which may contact neighboring carcasses. Samples were obtained both from hide removal locations that were close enough to hide pullers to be contacted by droplets and from locations that were not contacted by droplets. Higher pathogen prevalences, aerobic plate counts, and Enterobacteriaceae counts were observed at locations with samples contacted by the hide removal droplets. We conclude that the hide removal processes likely introduce pathogens into the air via a dispersion of liquid droplets and that these droplets may be an underappreciated source of hide-to-carcass contamination.

Tracking the sources of salmonella in ground beef produced from nonfed cattle.

The objective of this study was to determine the source(s) of Salmonella contamination in ground beef. One hundred dairy cows were harvested in a U.S. commercial beef processing plant. Samples of hides, carcasses after hide removal and before exposure to antimicrobial intervention, carcasses after all antimicrobial interventions, superficial cervical lymph nodes from the chuck, trim, ground beef, and air were obtained. Ninety-six percent of the hide samples, 47% of the carcasses before intervention, 18% of the lymph nodes, 7.14% of the trim, and 1.67% of the ground beef samples were positive for Salmonella. None of the samples obtained from the carcasses after the full complement of interventions and none of the air samples were positive for Salmonella. All Salmonella-positive samples were subjected to pulsed-field gel electrophoresis, and eight DNA Xba I restriction patterns were identified. The majority of isolates had one of two restriction digest patterns. The strain isolated from ground beef had the same pattern as the strains isolated from hides and from carcasses immediately after hide removal. The Salmonella isolates from trim samples and lymph nodes also had the same restriction digest pattern. These results indicate that hide and lymph nodes are the most likely sources of Salmonella in ground beef. Dressing practices that effectively reduce or eliminate the transfer of bacteria from hide to carcass and elimination of lymph nodes as a component of raw ground beef should be considered as measures to reduce Salmonella contamination of ground beef. Because total elimination of lymph nodes from ground beef is not possible, other approaches should be explored. Easily accessible lymph nodes could be screened for Salmonella very early in the slaughter process. When the results are positive for Salmonella, the corresponding carcasses should be fabricated separately at the end of the production run, and the trim from these carcasses should be subjected to a treatment that destroys Salmonella.

Characterization of Antimicrobial Resistance in Enterococcus spp. Recovered from a Commercial Beef Processing Plant

The objective of this study was to characterize antimicrobial resistance in Enterococcus spp. recovered from a commercial beef processing plant. Samples were obtained from conveyers used for moving carcasses before the start of operation (CC), 2 h after operation has started (DC), and from ground beef (GB). Randomly selected isolates from each positive sample (13 from CC; 28 from DC; 26 from GB) were confirmed to genus and species levels using PCR and the API 20 Strep kit (BioMérieux Canada, Inc., St. Laurent, Canada). A total of 199 isolates comprising 39, 84, and 76 from CC, DC, and GB, respectively, were used for antimicrobial resistance testing, major resistance genes detection, and genetic analysis. Enterococcus faecalis (87%) was the most common species found followed by Enterococcus faecium (10%). The majority of enterococci were highly associated with DC samples. About 42% of E. faecium from DC samples were resistant to quinupristin-dalfopristin. Resistance to lincomycin was observed in >90% of E. faecalis from all the three sample sources. The tetracycline-resistant enterococci (52%) were significantly higher in DC samples. Intermediate resistance to erythromycin was significantly higher in enterococci from CC and DC samples. The tetracycline and quinupristin-dalfopristin resistance in enterococci was highly correlated with the presence of tet(M) and vat(E) genes. The erm(B) gene was found in about 50% of the E. faecium isolates from GB samples and was also present in >12% of the E. faecalis isolates from all the three sample sources. Enterococci from individual sample sources were genetically similar. A number of E. faecalis from CC, DC, and GB were clustered together at >85% similarity level. These findings suggest that antimicrobial-resistant Enterococcus spp. are prevalent during commercial beef processing and can transfer between various locations in the plant and that a pool of resistance genes can be found in these enterococci.