Deli Ham Research Articles

Validation of the Microlab Salmonella for Detection of Salmonella O Group A-E in Selected Foods: AOAC Performance Tested MethodSM 052401.

Microlab Salmonella is an all-in-one solution for detection of Salmonella O Groups A-E that integrates, in a single disposable device, all elements to perform the analysis; a ready-to-use enrichment broth, a lateral flow immunochromatography test and a chemical agent for bacterial inactivation. Microlab Salmonella can be easily used on-site and does not require specific laboratory equipment or technical skills. The device is sealed during the analysis avoiding risks of contamination and is therefore safe to use in food production environments. This report details the method validation study for raw ground beef, raw turkey (thermal processed, marinated), fresh cheese, deli ham and pasteurized liquid egg. Matrix studies and inclusivity/exclusivity, product consistency/stability, and robustness testing were conducted to assess the method's performance. Inclusivity/exclusivity testing showed that the Microlab Salmonella method was able to detect Salmonella O Group A-E isolates while excluding the non-Salmonella strains. In the matrix studies the differences between the candidate and reference methods were not statistically significant. Minor variations in test parameters (enrichment time, time to read results, and enrichment temperature) did not affect the performance of the Microlab assay. There were no statistically significant differences between recently manufactured lots and those that were halfway through their expiration period or between those that were close to expiring. The reported data confirms that Microlab Salmonella is reliable for detecting Salmonella in raw ground beef, raw turkey (thermal processed, marinated), fresh cheese, pasteurized liquid egg and deli ham. Microlab Salmonella is validated to detect Salmonella in select food matrixes. Microlab Salmonella integrates the steps of enrichment, detection, and inactivation in a single device.

Comparative Evaluation of the SMARTCHECK® Listeria monocytogenes Detection Kit for GENECHECKER® UF-300 Real-Time PCR System for Select Foods: AOAC Performance Tested MethodSM 042101.

The candidate method, SMARTCHEK® Listeria monocytogenes Detection Kit, is designed for rapid detection of L. monocytogenes in select food matrixes, for use in conjunction with the Genesystems Rapi:chipTM and GENECHECKER®UF-300 real-time PCR system. The independent laboratory evaluation consisted of an inclusivity and exclusivity study, product consistency study, robustness study, stability study, and a matrix study. The paired matrix study tested stainless-steel environmental sponges, uncured ready-to-eat deli turkey, ready-to-eat deli ham, cooked shrimp, and fresh bagged spinach. The robustness study evaluated the method by changing three parameters. The accelerated stability and product consistency study was conducted at 8, 16, 24, 32, and 40 days. The candidate method was compared to the US Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, 8.11 Isolation and Identification of Listeria monocytogenes from Red Meat, Poultry, Ready-to-Eat Siluriformes (Fish) and Egg Products, and Environmental Samples and to the US Food and Drug Administration Bacteriological Analytical Manual Chapter 10: Detection of Listeria monocytogenes in foods and Environmental Samples, and Enumeration of Listeria monocytogenes in Foods following a paired study design. All 50 L. monocytogenes isolates were detected in all three broths tested for inclusivity, while all 37 non-L. monocytogenes isolates were correctly excluded. In the matrix study, the candidate method showed no significant differences between confirmed candidate method results and reference method results for all food matrixes evaluated. The candidate method is an effective method for the qualitative detection of L. monocytogenes in select food matrixes. The SMARTCHECK Listeria monocytogenes Detection Kit assay allows for fast, reliable detection of L. monocytogenes with results obtained in approximately 35 min after 18-48 h pre-enrichment, depending on the matrix.

Enabling Cost-Effective Screening for Antimicrobials against Listeria monocytogenes in Ham

Ready-to-eat meat products, such as deli ham, can support the growth of Listeria monocytogenes (LM), which can cause severe illness in immunocompromised individuals. The objectives of this study were to validate a miniature ham model (MHM) against the ham slice method and to screen antimicrobial combinations to control LM on ham by using response surface methology (RSM) as a time- and cost-effective high-throughput screening tool. The effect of nisin (Ni), potassium lactate and sodium diacetate, lauric arginate (LAG), lytic bacteriophage (P100), and ε-polylysine (EPL) added alone, or in combination, were determined on the MHM over 12 days of storage. Results showed the MHM accurately mimics the ham slice method because no statistical differences were found (P = 0.526) in the change of LM cell counts in MHM and slice counts after 12 days of storage at 4°C for treated and untreated hams. The MHM was then used to screen antimicrobial combinations by using an on-face design and three center points in a central composite design. The RSM was tested by using a cocktail of five LM strains isolated from foodborne disease outbreaks. Three levels of the previously mentioned antimicrobials were used in combination for a total of 28 runs performed in triplicate. The change of LM cell counts were determined after 12 days of storage at 4°C. All tested antimicrobials were effective on reducing LM cell counts on ham when added alone. A significant antagonistic interaction (P = 0.002) was identified by the RSM between LAG and P100, where this antimicrobial combination caused a 2.2-log CFU/g change of LM cell counts after 12 days of storage. Two interactions, between Ni and EPL (P = 0.058), and Ni and P100 (P = 0.068), showed possible synergistic effects against LM on the MHM. Other interactions were clearly nonsignificant, suggesting additive effects. In future work, the developed MHM in combination with RSM can be used as a high-throughput method to analyze novel antimicrobial treatments against LM.

Soleris®Enterobacteriaceae for the Detection of Enterobacteriaceae in Select Foods: AOAC Performance Tested MethodSM 121901.

BackgroundSoleris®Enterobacteriaceae is a growth-based, automated method for detection of Enterobacteriaceae in food.ObjectiveA study was conducted to validate the Soleris method for detection of Enterobacteriaceae in select foods (pasteurized milk, yogurt, mozzarella cheese, ice cream, dried milk, pasteurized liquid egg, frozen cooked chicken, deli ham, lettuce, and dry dog food) at a threshold of ≥ 10 CFU/g of product.MethodsInclusivity and exclusivity of the Soleris method were assessed by testing 55 and 38 target and non-target bacterial strains, respectively. Matrix testing was performed with one naturally contaminated and nine inoculated foods. Efficacy of the Soleris method was compared to that of the ISO 21528-2:2017 direct plating reference method using probability of detection analysis. Independent laboratory testing was conducted to verify method performance in two matrixes (yogurt and deli ham). Method robustness, stability, and lot-to-lot consistency of the Soleris reagents were also assessed.ResultsInclusivity of the Soleris test was 91% and exclusivity was 100%. In matrix testing, there were no significant differences in the number of positive results obtained with the Soleris and reference methods for any of the matrixes examined. Overall, of 370 test portions, there were 176 positive results by the Soleris method and 177 positive results by the reference procedure.ConclusionsSoleris Enterobacteriaceae is an effective method for detection of Enterobacteriaceae in the foods evaluated, with performance equivalent to that of the ISO 21528-2:2017 reference method.HighlightsThe Soleris method offers the advantages of labor savings and results within 18 h.

Validation Study of LuciPacTM A3 Surface for Hygiene Monitoring through Detection of ATP, ADP, and AMP from Stainless Steel Surfaces: AOAC Performance Tested MethodSM 051901.

The LuciPac A3 Surface Hygiene Monitoring System based on the detection of total adenylate, ATP+ADP+AMP (A3), has been developed by Kikkoman Biochemifa. This A3 swabbing assay kit was validated for Performance Tested MethodsSM (PTM) certification. The LuciPac A3 Surface Hygiene Monitoring System was evaluated for limit of detection (LOD) for each adenylate with pure analyte solutions, detection of food residues and microbial residues on stainless steel surfaces, interference by disinfectants, and selectivity of the method response. Pure analyte studies performed by the method developer and the independent laboratory showed good linearity (R2 > 0.9854) and repeatability precision (RSDr < 20% for ≥2.5 fmol/assay). The LOD values for each adenylate were around 10 relative light units or 2.5 fmol/assay. The repeatability precision in the method developer laboratory for the matrix study (raw chicken breast, sliced deli ham, orange juice, yogurt, and apple pie) and the microbial study (Cronobacter sakazakii, Lactobacillus acidophilus, and Saccharomyces cerevisiae) were 8-30% and 10-35%, respectively. The repeatability precision of independent laboratory testing was 13-27% for orange juice and 16-43% for ham. Interference by several disinfectants indicate that rinsing is recommended to be performed after the use of sanitizing agents and before testing with LuciPac A3 Surface. Selectivity testing revealed that no positive interference and no inhibition were caused by adenylate analogues. Instrument variation, lot-to-lot consistency, accelerated stability (30°C, 5 weeks) were confirmed, and the method was shown to be robust against shaking time. The LuciPac A3 Surface has been successfully validated. This A3 swabbing assay kit was qualified for PTM certification No. 051901.

Utilization of Phosphate Alternatives in Marinated Chicken Breast and Chunked and Formed Deli Ham

Experiments were conducted to determine the efficacy of replacing phosphates in marinated chicken and chunked and formed deli ham using alternative ingredient blends. For the marinated chicken study, broiler breasts were marinated with a 13% solution of 1.0% NaCl, water and either 0.35% sodium tripolyphosphate or a phosphate alternative. Treatment variables consisted of (1) 0.35% sodium tripolyphosphate (STP), (2) negative control (no phosphate, NP), (3) 0.83% Whey protein concentrate (WPC), (4) 0.83% Oat fiber (OF, marinated chicken only), or (5) 1.05% Oat fiber with dry vinegar (OFDV).The WPC, OF, and OF-DV treatments also included 1,000 ppm of a natural flavor that served as an antioxidant. The STP treatment yielded breast meat with less (P &lt; 0.05) cooking loss and a higher pH (P &lt; 0.05) than the NP and alternative ingredient treatments. On average, no differences were observed (P &gt; 0.05) in consumer acceptability for chicken breast appearance, texture and overall acceptability. For the ham study, each treatment formulation consisted of approximately 77% pork, 20% water, common commercial curing ingredients, and the following treatment effects: STP (0.4% STP), NP (no phosphate, NP), 1.3% OF-DV, and 1.1% WPC. STP had less cooking loss than all other treatments (P &lt; 0.05). The STP treatment had greater protein bind (P &lt; 0.05) than all other treatments, and the OF-DV treatment had greater protein bind than the WPC and NP treatments. The NP, STP, and WPC treatments were preferred (P &lt; 0.05) over the OF-DV treatment. Application of WPC or OF-DV may help meat processors meet current clean label trends if the decrease in yields for chicken breast and deli hams and the decrease in firmness of texture in deli hams is acceptable to processors and consumers.

Characterization of Enterococcus durans 152 bacteriocins and their inhibition of Listeria monocytogenes in ham

Listeria monocytogenes is a nonfastidious, widely occurring foodborne pathogen that is a major challenge to the food industry. Enterococcus durans 152, a confirmed L. monocytogenes-control microorganism, was isolated from floor drain samples from a food processing facility. In this study, the two bacteriocins produced by E. durans 152 were characterized and identified as Dur 152A (an enterocin L50A derivative with two amino acid substitutions of I→M) and enterocin L50B. The bacteriocins were then partially purified and evaluated for inhibitory activity to L. monocytogenes in deli ham. Results revealed that at 400 AU/ml, the bacteriocins prevented growth of listeria in deli ham for at least 10 weeks at 8 °C and at least 30 days at 15 °C. For comparison, 500 ppm Nisin controlled listeria growth for up to 6 weeks at 8 °C and up to 18 days at 15 °C. These findings reveal the potential for the bacteriocins of E. durans 152 to serve as anti-listerial agents in deli meat.

Utilization of Phosphate Alternatives in Chunked and Formed Deli Ham and Marinated Chicken Breast

ObjectivesConsumer demand for clean ingredient labels has led to research into natural alternatives to synthetically derived functional ingredients. Phosphates, including sodium tripolyphosphate, have been reported as an undesirable additive in meat products by some consumers. Phosphates are used by meat processors to increase yields, improve texture, and protect flavor. The objective of this research was to determine if the addition of phosphate substitutes including oat fiber, oat fiber with dried vinegar, and whey protein concentrate are viable natural alternatives to phosphate in ready-to-eat (RTE) marinated chicken breast.Materials and MethodsBroiler breast meat (0.19 to 0.25 kg per fillet) was marinated with formulations containing 1.0% NaCl and 0.4% sodium tripolyphosphate or a phosphate substitute treatment and water. The treatment variables consisted of positive phosphate, negative phosphate, whey protein concentrate (WPC), oat fiber, or oat fiber with dry vinegar. Treatments were vacuum tumbled at 25 mm hg for 30 min at 8 rpm with 0.91 kg of brine solution and 7.8 kg of chicken breast. Samples were measured for percent pick-up of brine, cooking loss, pH, color, and instrumental tenderness. Sensory evaluation was conducted (n = 180 total panelists) to evaluate the appearance, aroma, texture, flavor and overall acceptability of chicken breast treatments. A randomized complete block design with 3 replications was used to test the effect of adding whey protein concentrate, oat fiber, and oat fiber DV on quality parameters and sensory acceptability of chicken breast. Duncan’s multiple range test was utilized to separate the treatment means when significant differences occurred (P < 0.05).ResultsPhosphate treatments yielded breast meat with less (P < 0.05) cooking loss and a greater pH than the negative control and phosphate substitute treatments. No differences existed (P > 0.05) among treatments with respect to brine pick up and shear force. On average, no differences existed (P > 0.05) in consumer acceptability for appearance, texture and overall acceptability, with all mean values between like slightly and like moderately on the 9 point hedonic scale. Furthermore, 82% of panelists rated the positive phosphate treatment at least like slightly. The oat fiber treatment was liked slightly or greater by 77% of panelists, while 74% of panelists rated the whey protein concentrate treatment at least like slightly or greater. Both the oat fiber with dry vinegar and negative phosphate treatments were like slightly or greater by 68% of panelists. This indicates that formulating whey protein concentrate, and oat fiber into chicken marinades can effectively increase the percentage of panelists that like chicken breast as compared to the negative phosphate treatmentConclusionWhey protein concentrate and oat fiber have potential as phosphate alternatives in marinated chicken breast. Future research should be explored to determine ingredients that can increase negative charges on myofibrillar proteins to maximize yield and functionality for use in conjunction with oat fiber and whey protein concentrate as a potential phosphate replacer in meat systems.

Utilization of Phosphate Alternatives to Produce Chunked and Formed Deli Ham

ObjectivesThe objective of this study was to determine the efficacy of replacing phosphate with a natural alternative in chunked and formed deli ham.Materials and MethodsBoneless biceps femoris muscles were chunked into 2.54-cm cubes. Each treatment formulation (6 kg) consisted of approximately 77% pork (85% cubed meat and 15% finely chopped trim to improve protein binding), 20% water, 1.8% salt, 0.9% dextrose, 120 ppm sodium nitrite, 450 ppm sodium erythorbate and the following treatment effects: positive control (0.4% sodium tripolyphosphate, STP), negative control (no phosphate, NP), a 1.3% Fiber Dry Vinegar (FDV) blend, and a 1.1% whey protein concentrate blend (WPC). The ham formulations were vacuum tumbled (25 mm/hg of mercury) for four 20 min intervals with 10 min rest periods in-between. After the rest period of the third interval, the trim was added and the formulation was vacuum tumbled for the final 20 min. The contents of the tumbler were then stuffed into cellulose casings, tipper tied, heat processed in a smokehouse to an internal temperature of 74 C, and sliced into 1.27 cm slices for color and protein bind analysis Consumer acceptability testing (n = 60 panelists) was also conducted using a 9-point hedonic scale. A completely randomized design with 2 replications was utilized to evaluate treatment effects. When significant differences occurred (P < 0.05) among treatments, Fisher’s Protected Least Significance Test was utilized to separate treatment meansResultsThe STP treatment had less cooking loss than all other treatments (P < 0.05) at 9.3%. The cooking loss for the WPC treatment was less (P < 0.05) than that of the NP treatment % but was not different (P > 0.05) from the FDV treatment. The STP treatment had greater protein bind (P < 0.05) than all other treatments. In addition, the FDV treatment had greater protein bind than the WPC and NP treatments. On average, no differences (P < 0.05) existed between treatments with respect to consumer acceptability. Cluster analysis was conducted to determine if any variability could be determined among treatments since all hams were liked. Results indicated that 88% of consumers rated the STP treatment like moderately or greater, 73% of the panelists liked the NP treatment moderately or greater, and 85% of panelists liked the WPC and fiber treatments at least like moderately.ConclusionApplication of WPC or FDV may help meat processors meet current clean label trends if the decrease in cooking yields and firmness of texture was acceptable to processors and or consumers.

Comparison of process control viruses for use in extraction and detection of human norovirus from food matrices

Although RT-qPCR is a powerful tool for human norovirus (HuNoV) detection, low virus concentrations in potentially large sample volumes necessitate the use of inefficient sample processing step(s) prior to detection. Process control viruses (PCVs) are used to monitor the efficiency of these virus concentration steps. This study compared five PCVs [Mengovirus (Mengo), murine norovirus (MNV-1), MS2 coliphage, Tulane virus, and turnip crinkle virus (TCV)] to two HuNoV strains for recovery during the steps of elution, polyethylene glycol precipitation (PEG), and RNA extraction from select foods (lettuce and sliced deli ham). Results demonstrate high recovery efficiencies of HuNoV GI.6 and GII.4 using the methods described in this study: combined (sequential) losses during processing from sliced deli ham and lettuce were <1 log10 genome equivalent copies (GEC). When considering the processing steps separately, HuNoV loss was negligible after elution, and low after PEG precipitation (mean 0.5 log10 GEC) and RNA extraction (mean 0.1 log10 GEC). The virus that least mimicked the behavior of HuNoV during sample processing was MNV-1. Of the viruses tested, a commercial mengovirus strain gave recovery efficiencies closest to HuNoV, showing combined losses from sliced deli ham and lettuce of <1 log10 GEC and ~1 log10 GEC, respectively. All PCVs do not behave equivalently and validation of their performance is recommended before their routine use on an application-by-application basis.

MicroSEQ®Listeria spp. Detection Kit

Abstract The Applied Biosystems Performance Tested MethodSM for detecting Listeria species in food and environmental samples was compared to the Health Canada reference method (MFHPB-30) for the analysis of five ready-to-eat (RTE) meats (deli turkey, hot dogs, liver paté, deli ham, and raw fermented sausage) and a stainless steel surface. The MicroSEQ method includes the MicroSEQ®Listeria spp. Detection Kit and the option of two different sample preparation kits, either the automated high-throughput PrepSEQ™ Nucleic Acid Extraction Kit or the manual low- to mid-throughput PrepSEQ™ Rapid Spin Sample Preparation Kit. For each sample matrix, 20 replicates were analyzed at two inoculum levels: for RTE meats a low-level inoculum at 0.2–2 CFU/25 g and a high-level inoculum at 2–5 CFU/25 g; and for environmental surfaces, a low-level inoculum at 0.2–2 CFU/5 cm2 sampling area and a high-level inoculum at 2–5 CFU/5 cm2 sampling area. Five control replicates were also analyzed at 0 CFU/25 g (uninoculated) for food or 0 CFU/5 cm2 sampling area for environmental surface. Both sample preparation methods returned identical results. There was no statistically significant difference in the number of positive samples detected by the MicroSEQ Listeria species method and the MFHPB-30 reference method for three RTE meats and for the one stainless steel environmental surface tested. For deli turkey, there was a statistically significant difference in the number of positive results detected by the MicroSEQ method and the Health Canada MFHPB-30 reference method for the low inoculation level, with the MicroSEQ method detecting more positives. For hot dogs, statistical equivalence was not applicable since hot dogs were spiked with 10x Listeria innocua as competitive background, and the MicroSEQ method detects all known Listeria. Because the MicroSEQ method uses real-time PCR to detect pathogens, it provides faster time-to-results with equivalent detection compared to culture methods. The MicroSEQ method detects Listeria species within 2 to 3 h following 24 to 28 h enrichment compared to culture methods that take at least 5 days for presumptive positive results.

MicroSEQ®Listeria monocytogenes Detection Kit

Abstract The Applied Biosystems Performance Tested MethodSM for detecting Listeria monocytogenes in food and environmental samples was compared to the Health Canada reference method (MFHPB-30) for the analysis of five ready-to-eat (RTE) meats (deli turkey, hot dogs, liver paté, deli ham, and raw fermented sausage) and a stainless steel environmental surface. The MicroSEQ® method includes the MicroSEQListeria monocytogenes Detection Kit and the option of two different sample preparation kits, either the automated high-throughput PrepSEQ™ Nucleic Acid Extraction Kit or the manual low- to mid-throughput PrepSEQ Rapid Spin Sample Preparation Kit. For each sample matrix, 20 replicates were analyzed at two inoculum levels: for RTE meats, a low-level inoculum at 0.2–2 CFU/25 g and a high-level inoculum at 2–5 CFU/25 g; and for environmental surfaces, a low-level inoculum at 0.2–2 CFU/5 cm2 sampling area and a high-level inoculum at 2–5 CFU/5 cm2 sampling area. Five control replicates were also analyzed at 0 CFU/25 g (uninoculated) for food or 0 CFU/5 cm2 sampling area for environmental surface. Both sample preparation methods returned identical results. There was no statistically significant difference in the number of positive samples detected by the MicroSEQ Listeria monocytogenes method and the MFHPB-30 reference method for four of the five RTE meats and the one stainless steel surface tested. For deli turkey, there was a statistically significant difference in the number of positive results detected by the MicroSEQ method and the Health Canada MFHPB-30 reference method for the low inoculation level, with the MicroSEQ method detecting more positives. Because the MicroSEQ method uses real-time PCR to detect pathogens, it provides faster time-to-results compared to culture methods while at the same time demonstrating equivalent detection. The MicroSEQ method detects L. monocytogenes within 2 to 3 h following 24 to 28 h enrichment compared to culture methods that take at least 5 days for presumptive positive results.

DuPont BAX® System PCR Assay for Genus Listeria 24E

The DuPontTM BAX® System PCR assay for Genus Listeria 24E using 24 LEB was assessed to detect Listeria spp. from food and stainless steel surfaces. The assay protocol used in these studies includes test kit lysis reagents that differ from those used in previous BAX System PCR assays (and are similar to those in the BAX System reverse-transcriptase PCR test kit for Listeria spp.) and a new proprietary enrichment medium optimized for use with this test kit. The genomic target for PCR in the Genus Listeria 24E assay is the same as that used in the previously-validated BAX System PCR assay for Genus Listeria (AOAC-RI Performance Tested MethodSM 030502), but the redesign of the test kit and new medium allow for faster target cell growth, a more quantitative lysis of enriched cells and a faster time to result. Five foods—liver paté, hot dogs, raw fermented sausage, sliced deli turkey, and sliced deli ham—and one environmental surface type, stainless steel, were simultaneously analyzed with the BAX System Q7 instrument and the Health Canada MFHPB-30 method for detecting Listeria spp. One food type, hot dogs, was artificially inoculated with L. innocua and Enterococcus faecalis. The environmental surfaces were co-inoculated with both L. monocytogenes and E. faecalis; all the other matrixes were inoculated with a single strain of L. monocytogenes. No significant differences were found in method performance when the test method was compared with the reference method.

Comparative Evaluation of the VIDAS®Listeria monocytogenes Xpress (LMX) for the Detection of Listeria monocytogenes in a Variety of Foods

The VIDAS Listeria monocytogenes Xpress (LMX) test is an enzyme-linked fluorescent immunoassay designed for use with the automated VIDAS or mini-VIDAS instruments for the specific detection of L. monocytogenes using a 26 h proprietary enrichment broth. The VIDAS LMX method was validated according to harmonized AOAC Research Institute (RI) and Official Methods of Analysis guidelines in both the AOAC Performance Tested Method (PTM) and GovVal programs. In the PTM comparison studies, the VIDAS LMX method was compared to the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook, the U.S. Food and Drug Administration Bacteriological Analytical Manual, and AOAC Official Methods. The comparative food studies consisted of two main parts: internal testing and AOAC independent laboratory testing, which included seven food matrixes (deli ham, processed cheese, vanilla ice cream, cooked shrimp, smoked white fish, frozen spinach, and peanut butter). As part of the AOAC R1 GovVal program, the VIDAS LMX method was compared to the Health Canada MFHPB-30 method for the detection of L. monocytogenes in five ready-to-eat (RTE) meats (hot dogs, deli turkey, deli ham, fermented sausage, and liver paté). Twenty replicates of each inoculation level and five uninoculated controls were evaluated in each study. The LMX method also included the use ofchromogenic media, chromID Ottaviani Agosti agar and chromID L. mono. agar, for confirmation of LMX presumptive results. In both the PTM and GovVal evaluations, there were no significant differences in the Chi-square values for the LMX method when compared to reference methods. The additional parameters tested in the PTM evaluation (inclusivity, exclusivity, ruggedness, stability, and lot-to-lot) satisfied the AOAC RI performance requirements. In both the PTM and GovVal validation studies, the VIDAS LMX method demonstrated reliability as a rapid qualitative method for next-day detection of L. monocytogenes in a variety of foods, including RTE meats.

VIDAS®Listeria monocytogenes II (LMO2)

This AOAC GovVal study compared the VIDAS Listeria monocytogenes II (LMO2) to the Health Products and Food Branch MFHPB-30 reference method for detection of L. monocytogenes in ready-to-eat (RTE) meats. The VIDAS LMO2 test is an automated enzyme-linked fluorescent immunoassay for the detection of L. monocytogenes in foods. The LMO2 test, following the enrichment procedure from the MFLP-33 method, also included use of the chromogenic media, chromID Ottaviani Agosti Agar (OAA) and chromID Lmono for confirmation of LMO2 presumptive results. In previous AOAC validation studies comparing the VIDAS LMO2 method to the U.S. Food and Drug Administration Bacteriological Analytical Manual and U.S. Department of Agriculture-Food Safety and Inspection Service reference methods, LMO2 was approved as AOAC Official Method 2004.02 for the detection of L. monocytogenes in dairy products, vegetables, seafood, raw meats and poultry, and processed meats and poultry. The GovVal comparative study included 20 replicate test portions, each at two contamination levels for each matrix, where fractionally positive results (5-15 positive results/20 replicate portions tested) were obtained by at least one method at one level. Five uncontaminated controls were included. Chi-square analysis of the comparative data in this study indicates no statistical differences between the VIDAS LMO2 and the MFHPB-30 standard methods at the 5% level of significance. Confirmation of presumptive LMO2 results with the chromogenic OAA and Lmono media was shown to be equivalent to the appropriate reference method agars. The data demonstrate that the VIDAS LMO2 method is an acceptable alternative method to the MFHPB-30 standard culture method for the detection of L. monocytogenes in RTE meats, including liver paté, hot dogs, raw fermented sausage, sliced deli turkey, and sliced deli ham.

Comparison of public health impact of Listeria monocytogenes product-to-product and environment-to-product contamination of deli meats at retail.

This study compared the relative public health impact in deli meats at retail contaminated with Listeria monocytogenes by either (i) other products or (ii) the retail environment. Modeling was performed using the risk of listeriosis-associated deaths as a public health outcome of interest and using two deli meat products (i.e., ham and turkey, both formulated without growth inhibitors) as model systems. Based on reported data, deli meats coming to retail were assumed to be contaminated at a frequency of 0.4%. Three contamination scenarios were investigated: (i) a baseline scenario, in which no additional cross-contamination occurred at retail, (ii) a scenario in which an additional 2.3% of products were cross-contaminated at retail due to transfer of L. monocytogenes cells from already contaminated ready-to-eat deli meats, and (iii) a scenario in which an additional 2.3% of products were contaminated as a result of cross-contamination from a contaminated retail environment. By using a previously reported L. monocytogenes risk assessment model that uses product-specific growth kinetic parameters, cross-contamination of deli ham and turkey was estimated to increase the relative risk of listeriosis-associated deaths by 5.9- and 6.1-fold, respectively, for contamination from other products and by 4.9- and 5.8-fold, respectively, for contamination from the retail environment. Sensitivity and scenario analyses indicated that the frequency of cross-contamination at retail from any source (other food products or environment) was the most important factor affecting the relative risk of listeriosis-associated deaths. Overall, our data indicate that retail-level cross-contamination of ready-to-eat deli meats with L. monocytogenes has the potential to considerably increase the risk of human listeriosis cases and deaths, and thus precise estimates of cross-contamination frequency are critical for accurate risk assessments.

CONTROL OF LISTERIA MONOCYTOGENES IN HAM DELI LOAVES USING ORGANIC ACIDS

ABSTRACT Combinations of organic acids, sodium lactate (SL; Fisher Scientific Co. LLC., Pittsburgh, PA), potassium lactate (PL; City Chemical LLC., West Haven, CT) and sodium diacetate (SD; Spectrum Chemical MFG. Corp., Gardena, CA), were applied in the raw product and as a post‐cook dip to determine their inhibitory effect on Listeria monocytogenes in ham deli loaves. Loaves were formulated with an organic acid as an ingredient, cooked, cooled, inoculated with streptomycin‐resistant L. monocytogenes and then dipped in an organic acid treatment. Treatments consisted of PL in the raw product and PL in the dip, PL with SL/PL/SD dip, SL/SD with PL dip, and SL/SD with SL/PL/SD dip. Loaves were examined on a weekly basis for 56 days. Treatments containing PL with SL/PL/SD, SL/SD with PL, and SL/SD with SL/PL/SD had similar inhibition effects on L. monocytogenes from day 0 to day 42 (P &lt; 0.05). On day 56, the PL with SL/PL/SD and the SL/SD with SL/PL/SD treatments were similar (P &lt; 0.05). The PL with SL/PL/SD, SL/SD with PL, and SL/SD with SL/PL/SD treatments increased the lag phase of L. monocytogenes compared with distilled water control (P &lt; 0.05).PRACTICAL APPLICATIONSIncluding a food grade organic acid‐based product in the formulation and as a post‐cook dip treatment can result in the slower growth of Listeria monocytogenes in deli ham loaves. This approach could provide meat processors with a useful method for controlling this deadly pathogen in ready‐to‐eat meat products.

UTILIZATION OF DEIONIZED WATER AND NONMEAT ADJUNCTS TO IMPROVE QUALITY OF CHUNKED AND FORMED BONELESS CURED HAM FORMULATED WITH PALE, SOFT AND EXUDATIVE RAW MATERIAL

ABSTRACT In three separate trials, randomized complete block designs with three replications were utilized to test the effects of deionized water and pale, soft and exudative (PSE) pork percentage on the quality of smoked and retorted ham (with and without nonmeat adjuncts). Product quality was determined through the evaluation of water‐holding capacity, cooked color, protein–protein bind and sensory evaluation. Retorting revealed the potential to reduce the pale‐color effect of PSE meat that is present in raw material and smoked deli ham. In retorted ham, modified food starch and soy protein concentrate reduced (P &lt; 0.05) cook loss, and modified food starch improved color. Deionized water improved yields (1%) in smoked deli hams, and 25% pale pork was used without negatively affecting (P &gt; 0.05) sensory or instrumental quality in a retort pouch ham product. Modified food starch also increased yields (P &lt; 0.05) in retort pouch ham without negatively affecting sensory quality.

An Efficient and Rapid Method for Recovery of Norovirus from Food Associated with Outbreaks of Gastroenteritis

Noroviruses have emerged as the most common cause of foodborne outbreaks of acute nonbacterial gastroenteritis. In this study, two methods for the extraction of viruses from deli ham were compared. Using both methods, as little as 1 to 10 reverse transcription (RT)–PCR units of inoculated norovirus and enterovirus could be detected by nested RT-PCR assays. The fastest and most efficient extraction method based on TRIzol LS Reagent was chosen to identify viruses in food items associated with three different outbreaks. Norovirus was detected using nested (real time) RT-PCR assays that target the genome region routinely used for diagnosis of human cases, thereby facilitating the comparison of sequences detected in food and clinical specimens. For one outbreak, a norovirus sequence (163/163 nucleotides) identical to those detected in clinical samples was found on salami sliced by a food handler with a recent history of gastroenteritis. For the other two outbreaks, norovirus was detected on leftovers of spareribs and ham, but fecal samples from affected persons were not available. The methods used in this study may be useful in future outbreak investigations because the extraction method is easy to perform and suitable for this particular type of food and the detection method facilitates direct comparison of patient and food data.

PARTICLE SIZE AND NONMEAT ADJUNCT EFFECTS ON THE PROTEIN FUNCTIONALITY OF BONELESS CURED PORK FORMULATED WITH PSE AND RFN RAW MATERIAL

ABSTRACT A randomized complete block design with six replications was utilized to test the treatment effects of adjuncts (no adjuncts (C), 2% soy protein concentrate (SPC), and 2% SPC + 1.5% modified food starch (SPC + MFS)) and raw material size (2.54 ± 2.54 cm (CF) and 10 ± 10 cm (SF)) on the protein functionality in boneless cured pork produced from a combination of 25% PSE and 75% red, firm, and nonexudative (RFN) semimembranosus muscle. Utilization of the smaller raw material size, CF decreased (P &lt; 0.05) expressible moisture, CIE L*, and CIE b*values and also decreased (P &lt; 0.001) protein‐protein bind. SPC and SPC + MFS were effective in decreasing (P &lt; 0.05) cooking loss in the CF product. Formulations utilizing smaller particle size in a chunked and formed product demonstrate the potential to improve the water holding capacity and cooked color in deli ham rolls formulated from a combination of 25% PSE and 75% RFN pork.