3M™ Petrifilm™ Rapid Yeast and Mold Count Plate for the Enumeration of Yeasts and Molds in Dried Cannabis Flower: AOAC Official MethodSM 2014.05

BACKGROUND

The 3MTM Petrifilm™ Rapid Yeast and Mold Count (RYM) Plate is a sample-ready culture medium system which contains nutrients supplemented with antibiotics, a cold-water-soluble gelling agent, and an indicator system that facilitates yeast and mold enumeration.

OBJECTIVE

The 3M Petrifilm RYM Plate was validated for the enumeration of yeast and mold in dried cannabis flower through the AOAC Emergency Response Validation process.

METHODS

The performance of the 3M Petrifilm RYM Plate was compared to dichloran rose bengal chloramphenicol (DRBC) agar. Matrix data were normalized by log10 transformation and performance indicators included repeatability, difference of means, and inclusivity/exclusivity.

RESULTS

These studies demonstrated the 3M Petrifilm RYM Plate method detects and enumerates yeasts and molds from dried cannabis flower at low, medium, and high contamination levels. The average log counts at 25 or 28°C for 60 to 72 h were equivalent to the average log counts of the DRBC reference method at low, medium and high levels. In strain studies, all 71 yeasts and molds tested produced typical colony morphology on 3M Petrifilm RYM Plates. Of the 32 non-target bacterial strains tested, none were detected on 3M Petrifilm RYM Plates.

CONCLUSION

The 3M Petrifilm RYM Plate is a reliable method for the enumeration of live yeast and mold in dried cannabis flower.

HIGHLIGHTS

The 3M Petrifilm RYM Plate allows for rapid detection of yeast and mold within 60 to 72 h of incubation. Up to 40 sample-ready plates can be stacked during incubation to save space.

3M™ Petrifilm™ Rapid Aerobic Count (RAC) Plate Method for the Enumeration of Aerobic Bacteria on Selected Surfaces: AOAC Official MethodSM 2015.13

BACKGROUND

The 3M™ Petrifilm™ Rapid Aerobic Count (RAC) Plate is a sample-ready culture medium system designed to facilitate colony enumeration in 24 h (48 h for dry powders) for selected food and environmental surfaces.

OBJECTIVE

The objective of this study is to evaluate the 3M Petrifilm RAC Plate in a matrix extension study for the enumeration of aerobic bacteria on stainless steel, sealed concrete, and rubber surfaces.

METHOD

The 3M Petrifilm RAC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual, Ch. 3 (January 2001): Aerobic Plate Count in a paired matrix study for enumeration of aerobic bacteria on stainless steel, sealed concrete, and rubber environmental surfaces.

RESULTS

The 3M Petrifilm RAC Plate showed no statistically significant differences when compared to the reference method for enumeration of aerobic bacteria from stainless steel, sealed concrete, and rubber environmental surfaces. There were no significant statistical differences between the 3M Petrifilm RAC Plate and reference method results for the three matrixes evaluated.

CONCLUSIONS

The 3M Petrifilm RAC Plate is an effective plating method for aerobic plate count when analyzing stainless steel, sealed concrete, and rubber surfaces.

HIGHLIGHTS

The 3M Petrifilm RAC Plate is robust, quick, and simple to perform, providing enumerable colonies in 22 to 26 h after incubation when compared to the 48 h of the reference method. The small size of the Petrifilm Plate allows for less space to be occupied by plates in the incubators. The visual biochemical and enzymatic indicators make enumeration of colonies a simple task by presenting colonies in either a blue or red color.

3M™ Petrifilm™ Rapid Yeast and Mold Count Plate Method for the Enumeration of Yeast and Mold on Selected Surfaces: AOAC Official Method 2014.05

BACKGROUND

The 3M™ Petrifilm™ Rapid Yeast and Mold Count (RYM) Plate contains nutrients supplemented with antibiotics, a cold-water-soluble gelling agent, and an indicator system that facilitates yeast and mold enumeration in 48-60 h.

OBJECTIVE

The objective of this study is to evaluate the 3M Petrifilm RYM Plate in a matrix extension study for the enumeration of yeast and mold on stainless steel, sealed concrete, and rubber surfaces.

METHODS

The 3M Petrifilm RYM Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual, Ch. 18: Yeasts, Molds and Mycotoxins in a paired matrix study for enumeration of yeast and mold on stainless steel, sealed concrete, and rubber environmental surfaces.

RESULTS

The 3M Petrifilm RYM Plate demonstrated equivalent performance to the reference method for enumeration of yeast and mold from stainless steel, sealed concrete, and rubber environmental surfaces. There were no significant statistical differences between the 3M Petrifilm RYM Plate and reference method results for the three matrixes evaluated.

CONCLUSION

The 3M Petrifilm RYM Plate is an effective plating method for enumerating yeast and mold when analyzing stainless steel, sealed concrete, and rubber surfaces.

HIGHLIGHTS

The 3M Petrifilm RYM Plate method allows the user to obtain accurate results within 48-60 h in the matrices evaluated for the presence of yeast and mold when incubated at 25 ± 1°C or 28 ± 1°C. Interpretation and colony counting was straightforward and the 3M Petrifilm RYM Plate method required no additional agar or Petri dishes, creating an easier workflow by cutting down on supplies, sample plating time, and most noticeably, occupying less space in the incubator.

3M™ Petrifilm Yeast and Mold Count Plate for the Enumeration of Yeasts and Molds in Dried Cannabis Flower: AOAC Official MethodSM 997.02

BACKGROUND

The 3M™ Petrifilm™ Yeast and Mold (YM) Count Plate is a sample-ready culture medium system that contains nutrients supplemented with antibiotics, a cold-water-soluble gelling agent, and an indicator system that facilitates yeast and mold enumeration.

OBJECTIVE

The 3M Petrifilm YM Plate was validated for enumeration of yeast and mold in dried cannabis flower through the AOAC Emergency Response Validation process.

METHODS

The performance of the 3M Petrifilm YM Plate was compared to that of Dichloran Rose Bengal Chloramphenicol (DRBC) agar. Matrix data were normalized by log10 transformation, and performance indicators included repeatability, difference of means, and inclusivity/exclusivity.

RESULTS

These studies demonstrated that the 3M Petrifilm YM Plate method detects and enumerates yeasts and molds from cannabis flower at low, medium, and high contamination levels, and the average log counts at 20-25°C for 5 days were equivalent to the average log counts of the DRBC reference method. In strain studies, 59 out of 60 yeasts and molds produced typical colony morphology on 3M Petrifilm YM Plates. Of the nontarget bacterial strains tested, 38 out of 39 strains were not detected on 3M Petrifilm YM Plates.

CONCLUSIONS

The 3M Petrifilm YM Plate is a reliable method for the enumeration of live yeast and mold in dried cannabis flower.

HIGHLIGHTS

The 3M Petrifilm YM Plate allows for detection of yeast and mold within 5 days of incubation. The sample-ready plates can be incubated at 20-25°C and can be stacked up to 20 plates, thus providing user flexibility and saving incubator space.

Validation of the 3M™ Molecular Detection Assay 2—STEC Gene Screen (stx) for Detection of Shiga Toxin Gene (stx1 and/or stx2) in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodSM 071903

Background

The 3M™ Molecular Detection Assay 2—STEC Gene Screen (stx) method is based on gene amplification by the use of real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing Escherichia coli (STEC) in enriched products. The 3M Molecular Detection Assay 2—STEC Gene Screen (stx) was approved as AOAC Performance Tested MethodSM Certificate No. 071903.

Objective

This matrix extension study evaluated the 3M Molecular Detection Assay 2—STEC Gene Screen (stx) method for detection of STECs in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size.

Method

Testing followed procedures outlined in 3M Molecular Detection Assay 2—STEC Gene Screen (stx) product instructions and Standard Method Performance Requirement (SMPR®) for Detection of Shiga Toxin-Producing Escherichia coli in Cannabis and Cannabis Products (AOAC SMPR 2020.012). The method was evaluated at low, high, and non-inoculated levels.

Results

Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2—STEC Gene Screen (stx) results and the SMPR 2020.012 recommended cultural confirmations.

Conclusions

This study provides data that demonstrate the 3M Molecular Detection Assay 2—STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of STECs in dried cannabis flower and dried hemp flower.

Highlights

The 3M Molecular Detection Assay 2—STEC Gene Screen (stx) method is suitable for the rapid and specific detection of STECs in dried cannabis flower and dried hemp flower.

Validation of the 3M™ Molecular Detection Assay 2—STEC Gene Screen (stx and eae) for Detection of Shiga Toxin Gene (stx1 and/or stx2) and Intimin Gene (eae) in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodSM 071902

Background

The 3M™ Molecular Detection Assay 2—STEC Gene Screen (stx and eae) method is based on gene amplification by the use of real time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) and intimin gene (eae) from Shiga toxin-producing Escherichia coli (STEC) in enriched products. The 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) was approved as AOAC Performance Tested MethodSM Certificate No. 071902.

Objective

This matrix extension study evaluated the 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) method for detection of STECs in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size.

Method

Testing followed procedures outlined in 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) product instructions and Standard Method Performance Requirements (SMPR®) for Detection of Shiga Toxin-Producing Escherichia coli in Cannabis and Cannabis Products (AOAC SMPR 2020.012). The method was evaluated at low, high, and non-inoculated levels.

Results

Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) results and the SMPR 2020.012 recommended cultural confirmations.

Conclusions

This study provides data that demonstrate the 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) is a reliable method for the rapid and specific detection of STEC organisms in dried cannabis flower and dried hemp flower.

Highlights

The 3M Molecular Detection Assay 2—STEC Gene Screen (stx and eae) method is suitable for the rapid and specific detection of STEC organisms in dried cannabis flower and dried hemp flower.

Validation of the 3MTM Molecular Detection Assay 2—Salmonella for detection of Salmonella in Dried Cannabis Flower and Dried Hemp Flower: AOAC Performance Tested MethodsSM 091501

Background

The 3M™ Molecular Detection Assay 2—Salmonella method is based on real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Salmonella in enriched products. The 3M Molecular Detection Assay 2—Salmonella was approved as AOAC INTERNATIONAL (AOAC) Performance Tested Method^SM (PTM) Certificate No. 091501 and as AOAC Official Method of Analysis^SM2016.01.

Objective

This matrix extension study evaluated the 3M Molecular Detection Assay 2—Salmonella for detection of Salmonella in dried cannabis flower [>0.3% delta 9-tetrahydrocannabinol (THC)] and dried hemp flower (≤0.3% THC) at a 10 g test portion size.

Method

Matrix studies in dried cannabis and hemp flowers followed procedures outlined in 3M Molecular Detection Assay 2—Salmonella product instructions and Standard Method Performance Requirement (SMPR^®) for Detection of Salmonella species in Cannabis and Cannabis Products (AOAC SMPR 2020.002). The method was evaluated at low, high, and non-contaminated levels.

Results

Results showed no statistically significant difference between the presumptive positive 3M Molecular Detection Assay 2—Salmonella results and the SMPR 2020.002 recommended cultural confirmations.

Conclusions

This study demonstrates that the 3M Molecular Detection Assay 2—Salmonella is a reliable method for the rapid and specific detection of Salmonella in dried cannabis flower and dried hemp flower.

Highlights

The 3M Molecular Detection Assay 2—Salmonella method is suitable for the rapid and specific detection of Salmonella in dried cannabis flower and dried hemp flower.

OUP accepted manuscript

Background

The 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) method is based on gene amplification by the use of real-time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC) in enriched foods.

Objective

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method was evaluated as a Level 2 method modification to add new matrixes to the certified claim: 25 g fresh raw ground beef (approximately 75% lean), 375 g raw beef trim (approximately 75% lean), 375 g fresh raw ground pork (approximately 70% lean), 375 g fresh raw poultry parts, and 25 g sprouts.

Methods

Matrix studies were conducted to assess the method’s performance compared to the US Department of Agriculture Food Safety and Inspection Service Microbiology Laboratory Guidebook, 5C.00 for meat and poultry, and to the US Food and Drug Administration Bacteriological Analytical Manual, Ch. 4A for sprouts, using an unpaired study design.

Results

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method demonstrated no significant differences between presumptive and confirmed results or between candidate and reference method results for any of the matrices tested.

Conclusion and Highlights

The data collected in these studies demonstrate that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of STEC in fresh raw ground beef (approximately 75% lean), fresh raw beef trim (approximately 75% lean), fresh raw ground pork (approximately 70% lean), fresh raw poultry parts, and sprouts.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (Stx) for the Detection of Shiga Toxin Gene (stx1 and/or stx2) in Fresh Raw Ground Beef and Fresh Spinach: AOAC® Performance Tested MethodSM 071903

Background

The 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx) method is based on gene amplification by the use of real time loop-mediated isothermal amplification when used with the 3M Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) from Shiga toxin-producing Escherichia coli (STEC) in enriched foods. The stx assay does not differentiate between stx1 and stx2 but detects the presence of stx1 and/or stx2.

Objective

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method was evaluated for AOAC^®  Performance Tested Methods^SM certification.

Methods

Matrix studies, inclusivity/exclusivity, robustness testing, product stability, and lot-to-lot variability testing were conducted to assess the method’s performance.

Results

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) demonstrated equivalent results to the United States Department of Agriculture/Food Safety and Inspection Service Microbiology Laboratory Guidebook Chapter 5C.00 reference method for fresh raw ground beef, and the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 4A reference method for fresh spinach. The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) detected all STEC E. coli strains (E. coli strains with stx1 and/or stx2 genes) and did not detect any of the 45 strains from the exclusivity panel. Robustness testing indicated that small variations in critical test parameters did not adversely affect the assay’s performance. Product consistency and stability testing demonstrated no differences between the lots evaluated.

Conclusion

The data collected in these studies demonstrate that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) is a reliable method for the rapid and specific detection of Shiga toxin-producing E. coli in raw ground beef and spinach.

Highlights

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx) method is suitable for the rapid and specific detection of Shiga toxin-producing E. coli in fresh raw ground beef, and spinach.

Validation of the 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) for the Detection of Shiga Toxin Gene (stx and eae) in Fresh Raw Beef Trim, Fresh Raw Ground Beef and Fresh Spinach: AOAC® Performance Tested MethodSM 071902

BACKGROUND

The 3M™ Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method is based on gene amplification using real time loop-mediated isothermal amplification with the 3M™ Molecular Detection System for the rapid and specific detection of Shiga toxin gene (stx1 and/or stx2) and intimin gene (eae) from Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC) in enriched foods.

OBJECTIVE

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method was evaluated for AOAC® Performance Tested MethodsSM certification.

METHODS

Matrix studies, inclusivity/exclusivity, robustness, product stability and lot-to-lot variability testing were conducted to assess the method's performance.

RESULTS

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) demonstrated equivalent results to the U. S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook 5C.00 for fresh raw beef trim and fresh raw ground beef, and to U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 4A for fresh spinach. The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) detected 50 of 50 E. coli strains with stx1 and/or stx2 genes, and the eae gene, and detected zero of 40 strains from the exclusivity panel. Robustness testing indicated that small variations in critical test parameters did not adversely affect the assay's performance. Product consistency and stability testing demonstrated no differences between the lots evaluated.

CONCLUSION

The data collected demonstrates that the 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) is a reliable method for the rapid and specific detection of STEC in raw beef trim, raw ground beef, and spinach.

HIGHLIGHT

The 3M Molecular Detection Assay 2 - STEC Gene Screen (stx and eae) method is suitable for the rapid and specific detection of STECs in raw beef trim, raw ground beef, and spinach.

Validation of the 3M™ Petrifilm™ Coliform Count Plate for Enumeration of Coliforms in Bottled Water: AOAC® Performance Tested MethodSM 082101

Background

The 3M^™ Petrifilm^™ Coliform Count (CC) Plate is a sample-ready-culture medium system which contains modified Violet Red Bile nutrients, a cold-water-soluble gelling agent, and a tetrazolium indicator that facilitates colony enumeration.

Objective

To validate the 3M Petrifilm CC Plate method for bottled water through the AOAC^®  Performance Tested Method(s)^SM program.

Methods

The performance of the 3M Petrifilm CC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual Chapter 4, Section III.D for the enumeration of coliforms in bottled water. Matrix data were normalized by log₁₀ transformation and performance indicators included repeatability and difference of means with 90 and 95% confidence intervals. Inclusivity, exclusivity, robustness, and product consistency and stability were evaluated.

Results

This study demonstrated that the 3M Petrifilm CC Plate method detects and enumerates coliforms from bottled water. The average log₁₀ counts of the 3M Petrifilm CC Plate method were equivalent to or better than the average log₁₀ counts of the reference method. Results from inclusivity and exclusivity studies demonstrated that the 3M Petrifilm CC Plate method differentiated coliforms from non-coliform strains. In product consistency, stability, and robustness testing, different lots of 3M Petrifilm CC Plates and small deviations in incubation time and temperature did not affect test results.

Conclusion

The 3M Petrifilm CC Plate method is an accurate and robust method for the enumeration of coliforms in bottled water.

Highlights

The 3M Petrifilm CC Plate allows for detection of confirmed coliforms within 24 h. Up to 20 sample-ready plates can be stacked during incubation, providing flexibility and saving space.

Evaluation of the 3M™ Environmental Scrub Sampler with Wide-Spectrum Neutralizer: AOAC® Performance Tested MethodSM 022104

BACKGROUND

The 3M™ Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is a non-specific sampling device intended for use for environmental monitoring surface sampling.

OBJECTIVE

To evaluate 3M Wide Spectrum Neutralizer using the 3M Environmental Scrub Samplers for AOAC Performance Tested MethodsSM (PTM) certification.

METHODS

Matrix studies, inclusivity/exclusivity, product consistency/stability, neutralization, and robustness testing were conducted for Salmonella and Listeria species. Stainless steel, sealed concrete, and plastic environmental surfaces were evaluated in the matrix study comparing the performance of the 3M™ method for sample collection to that of the U.S Food and Drug Administration/Bacteriological Analytical Manual reference methods. Four classes of sanitizers, quaternary ammonium, high acid, hydrogen/peroxyacetic acid and chlorine/bleach-based, were assessed in the neutralization study following ASTM E1054-08, Standard Test Methods for Evaluation of Antimicrobial Agents. The other testing parameters followed typical PTM study design.

RESULTS

In matrix studies the 3M sampling device demonstrated no significant differences between candidate and reference sampling method results. All inclusivity organisms were detected, and all exclusivity organisms were excluded for both Salmonella and Listeria strains when tested by the appropriate FDA/BAM detection method. Robustness, product consistency, and stability studies showed the sampling device is not affected by lot or testing parameter differences. The Wide Spectrum Neutralizer was proven to effectively neutralize sanitizers at the concentrations tested and was itself shown to be non-toxic and did not affect target microorganism recovery.

CONCLUSIONS

The 3M Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is an effective, stable, robust sampling device for the recovery of Salmonella spp. and Listeria spp.

HIGHLIGHT

The 3M Environmental Scrub Sampler with 10 mL Wide Spectrum Neutralizer is an acceptable sampling device for use in FDA BAM Salmonella and Listeria reference methods.

Evaluation of VIDAS Listeria monocytogenes II (LMO2) Immunoassay Method for the Detection of Listeria monocytogenes in Foods: Collaborative Study

A multilaboratory study was conducted to compare the VIDAS®Listeria monocytogenes II (LMO2) immunoassay and the standard cultural methods for the detection of Listeria monocytogenes in foods. Five food types—vanilla ice cream, brie cheese, cooked roast beef, frozen green beans, and frozen tilapia fish—at 3 levels were analyzed by each method. A total of 26 laboratories representing government and industry participated. In this study, 1404 test portions were analyzed of which 1152 were used in the statistical analysis. There were 448 positive by the VIDAS LMO2 assay and 457 positive by the standard culture methods. A χ2 analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting χ2 value, 0.36, indicates that overall, there are no statistical differences between the VIDAS LMO2 assay and the standard methods at the 5% level of significance.

Evaluation of the VIDAS® Listeria (LIS) Immunoassay for the Detection of Listeria in Foods Using Demi-Fraser and Fraser Enrichment Broths, as Modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06)

A multilaboratory study was conducted to compare the VIDAS® LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types—brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef—at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.

3M™ Petrifilm™ Enterobacteriaceae Count Plate Method for Enumeration of Enterobacteriaceae in Selected Foods: Collaborative Study

The practice of detecting and enumerating all oxidase-negative, glucose-fermenting-Gram-negative rods (i.e., the family Enterobacteriaceae) isused to indicate unsanitary or inadequate food processing conditions. The objective of this interlaboratory collaborative study was to evaluate and compare the methods described in Standard Methods for the Examination of Dairy Products (SMEDP) and the Compendium of Methods for the Microbiological Examination of Foods (Compendium) with a commercial product, the 3M™ Petrifilm™ Enterobacteriaceae Count Plate, for the recovery of Enterobacteriaceae in foods. Six foods—cheddar cheese, milk, flour, frozen prepared meals, frozen broccoli, and nut pieces—were analyzed for Enterobacteriaceae by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test portions consisting of a control test portion and 3 levels of inoculated test portion, each in duplicate. Each test portion was tested by the Petrifilm Enterobacteriaceae Count Plate method as well as the SMEDP or Compendium methods. The precision estimates (repeat-ability or within-laboratory variation, and reproducibility or between-laboratory variation) were calculated with standard statistical techniques.

3M™ Petrifilm™ Staph Express Count Plate Method for the Enumeration of Staphylococcus aureus in Selected Dairy Foods: Collaborative Study

The 3M™ Petrifilm™ Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Five foods—ice cream, raw milk, yogurt, whey powder, and cheese—were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 5 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

Petrifilm™ Rapid S. aureus Count Plate Method for Rapid Enumeration of Staphylococcus aureus in Selected Foods: Collaborative Study

A rehydratable dry-film plating method for Staphylococcus aureusin foods, the 3M™ Petrifilm™ Rapid S. aureus Count Plate method, was compared with AOAC® Official MethodSM 975.55 (Staphylococcus aureus in Foods). Nine foods—instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard—were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.

Evaluation of the VIDAS Listeria (LIS) immunoassay for the detection of Listeria in foods using demi-Fraser and Fraser enrichment broths, as modification of AOAC Official Method 999.06 (AOAC Official Method 2004.06)

A multilaboratory study was conducted to compare the VIDAS LIS immunoassay with the standard cultural methods for the detection of Listeria in foods using an enrichment modification of AOAC Official Method 999.06. The modified enrichment protocol was implemented to harmonize the VIDAS LIS assay with the VIDAS LMO2 assay. Five food types--brie cheese, vanilla ice cream, frozen green beans, frozen raw tilapia fish, and cooked roast beef--at 3 inoculation levels, were analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study, 1206 test portions were tested, of which 1170 were used in the statistical analysis. There were 433 positive by the VIDAS LIS assay and 396 positive by the standard culture methods. A Chi-square analysis of each of the 5 food types, at the 3 inoculation levels tested, was performed. The resulting average Chi square analysis, 0.42, indicated that, overall, there are no statistical differences between the VIDAS LIS assay and the standard methods at the 5% level of significance.

3M Petrifilm Staph Express Count plate method for the enumeration of Staphylococcus aureus in selected dairy foods: collaborative study

The 3M Petrifilm Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Five foods--ice cream, raw milk, yogurt, whey powder, and cheese--were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 5 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

3M Petrifilm Staph Express Count plate method for the enumeration of Staphylococcus aureus in selected types of processed and prepared foods: collaborative study

The 3M Petrifilm Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Five foods--frozen lasagna, custard, frozen mixed vegetables, frozen hashbrowns, and frozen batter-coated mushrooms--were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 5 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.

3M Petrifilm enterobacteriaceae count plate method for enumeration of enterobacteriaceae in selected foods: collaborative study

The practice of detecting and enumerating all oxidase-negative, glucose-fermenting-Gram-negative rods (i.e., the family Enterobacteriaceae) is used to indicate unsanitary or inadequate food processing conditions. The objective of this interlaboratory collaborative study was to evaluate and compare the methods described in Standard Methods for the Examination of Dairy Products (SMEDP) and the Compendium of Methods for the Microbiological Examination of Foods (Compendium) with a commercial product, the 3M Petrifilm Enterobacteriaceae Count Plate, for the recovery of Enterobacteriaceae in foods. Six foods--cheddar cheese, milk, flour, frozen prepared meals, frozen broccoli, and nut pieces--were analyzed for Enterobacteriaceae by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test portions consisting of a control test portion and 3 levels of inoculated test portion, each in duplicate. Each test portion was tested by the Petrifilm Enterobacteriaceae Count Plate method as well as the SMEDP or Compendium methods. The precision estimates (repeatability or within-laboratory variation, and reproducibility or between-laboratory variation) were calculated with standard statistical techniques.

Evaluation of the 3M Petrifilm Enterobacteriaceae Count plate method for the enumeration of Enterobacteriaceae in foods

Results of the 3M Petrifilm Enterobacteriaceae Count (EB) plate method were compared with those of the standard violet red bile glucose agar (VRBG) method for the detection and enumeration of Enterobacteriaceae. Studies involving 107 bacterial strains demonstrated that the Petrifilm EB plate method is as sensitive as and more selective than the VRBG method. Sixty of the 62 pure Enterobacteriaceae cultures were recovered by both methods. In addition, 38 of the 45 non-Enterobacteriaceae organisms did not grow on the Petrifilm EB plate, while 28 of the 45 non-Enterobacteriaceae organisms did not grow on the VRBG plate. Colony counts from 174 naturally contaminated and 120 artificially inoculated dairy and nondairy food samples showed that the Petrifilm EB plate method performed as well as or better than the standard VRBG method for the enumeration of Enterobacteriaceae.

Petrifilm rapid S. aureus Count Plate method for rapid enumeration of Staphylococcus aureus in selected foods: collaborative study

A rehydratable dry-film plating method for Staphylococcus aureus in foods, the 3M Petrifilm Rapid S. aureus Count Plate method, was compared with AOAC Official Method 975.55 (Staphylococcus aureus in Foods). Nine foods-instant nonfat dried milk, dry seasoned vegetable coating, frozen hash browns, frozen cooked chicken patty, frozen ground raw pork, shredded cheddar cheese, fresh green beans, pasta filled with beef and cheese, and egg custard-were analyzed for S. aureus by 13 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample and 3 levels of inoculated test sample, each in duplicate. The mean log counts for the methods were comparable for pasta filled with beef and cheese; frozen hash browns; cooked chicken patty; egg custard; frozen ground raw pork; and instant nonfat dried milk. The repeatability and reproducibility variances of the Petrifilm Rapid S. aureus Count Plate method were similar to those of the standard method.