Food Testing

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides food testing information for microbiological and physiochemical analyses available at Public Health Ontario (PHO).

This new test information sheet consists of a consolidation of all food analyses.

*Uncontrolled print copy. Valid only on day of print: 01 May 2024.

Testing Indications

Acceptance/Rejection Criteria

Refer to the Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing.

Specimen Collection and Handling

Specimen Requirements

Test Requested

Required Requisition(s)

Specimen Type

Minimum Volume

Collection Kit

Food Bacteriology¹

Food Bacteriology Requisition

Food – indicate if part of a meal, control, or follow up²

200 grams

Requisition for Specimen Containers and Supplies form

For items not listed in the form, please specify on the comment section:

Sterile sampling bags with wire closure, record “Food Bag PT# 300240 B /250”

AND

Environmental swabs, specify number of swabs requested

Submission and Collection Notes

Complete all fields of the requisition form, including:

Test(s) requests (specific analyses may be requested using the “Comments” section)
Reason for testing (select illness or no illness)
Include any additional critical information such as outbreak and investigation number or confirmed etiological agent

For environmental samples, label as outlined in the Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing.

Storage and Transport

For shipping instructions, refer to the Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing.

Special Instructions

Shipping containers used for food samples should be dedicated to food samples and not be used for other types of samples. DO NOT SHIP WITH CLINICAL SPECIMENS.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Food testing is performed Monday to Saturday at PHO’s laboratory, Toronto. Turnaround time is up to 7 business days from receipt at PHO’s laboratory, Toronto. Additional time may be required for confirmation testing, where applicable. Yersinia spp. testing turnaround time is up to 14 business days from receipt at PHO’s laboratory, Toronto.

Test Methods

The following quantitative food analyses are performed by culture techniques:

Aerobic Colony Count, Health Canada, MFHPB-18 methodology
Bacillus cereus Group count, FDA/BAM Chapter 14, modified methodology
Clostridium perfringens count, FDA/BAM Chapter 16, modified methodology
Total Coliforms count, FDA/BAM Chapter 4, modified methodology
Escherichia coli count, FDA/BAM Chapter 4, modified methodology
Staphylococcus aureus count, Health Canada, MFHPB-21 modified methodology
Total Gram Negative Count, PHO’s laboratory methodology
Yeast and Mould, Health Canada, MFHPB-22 modified methodology

The following qualitative food analyses are performed by culture, molecular, and/or other techniques:

Campylobacter spp. culture, PHO’s laboratory methodology
E. coli O157:H7 culture, Health Canada, MFHPB-10 modified methodology
Listeria monocytogenes culture, Health Canada, MFHPB-30 methodology
Listeria monocytogenes RT-PCR, AOAC RI 011002 methodology*
pH physiochemical analysis, Health Canada, MFHPB-03 modified methodology
Phosphatase physiochemical analysis, PHO’s laboratory methodology
Salmonella spp. culture, Health Canada, MFHPB-20 modified methodology
Salmonella spp. RT-PCR, AOAC RI 031001 methodology
Shigella spp. culture, Health Canada, MFLP-25 methodology
Staphylococcalenterotoxin, Enzyme Linked Fluorescent Immunoassay technique, Health Canada, MFLP-65 methodology
Vibrio spp., FDA BAM Chapter 9 methodology
Water activity (Aw) physiochemical analysis, Health Canada, MFLP-66 methodology
Yersinia enterocolitica culture, PHO’s laboratory methodology

Algorithm

PCR screening (Listeria monocytogenes* and Salmonella spp.) and confirmatory testing is performed on food samples, which are detected or indeterminate by PCR.

*RT-PCR will be used in the detection of Listeria monocytogenes from vegetable based products, seafood, dairy products, and environmental swab samples. All other commodities will be analyzed using the routine culture method.

Interpretation

The following table provides possible test results with associated interpretations for food testing (culture):

Result	Interpretation	Comments
<1000 CFU/gram to >200, 000 CFU/gram	Unsatisfactory levels for ACC is dependent on food category: Category 1: ≥ 10⁵, Category 2: ≥ 10⁷, Category 3: N/A Category 1 – Cooked foods that do not require handling or processing; i.e., soups, bread, quiche, cooked meat, fish & seafood, vegetables, etc. Category 2 – Cooked foods that require further handling prior to or during the preparation of the final product; i.e., hot dogs, sandwiches, burgers, etc. Category 3 – Foods that have a high ACC due to the normal microbial flora associated; i.e., pitas, potato or pasta salad, salad rolls, fresh fruits, raw vegetables, cheese, yogurt, deli meats, etc.	Applicable to: Aerobic colony count testing
<100 CFU/gram to >200,000 CFU/gram	The unsatisfactory level for food is ≥ 10⁴ CFU/gram (potentially hazardous)	Applicable to: Bacillus cereus group, Clostridium perfringens and Staphylococcus aureus testing
<3 MPN/gram to >1,000 MPN/gram	Presence of coliforms in a processed, cooked, ready-to-eat food is indicative of inadequate processing or post processing contamination resulting from poor handling of the product. A satisfactory limit cannot be applied to uncooked or raw foods such as salads and salad ingredients, raw fruits and vegetables, raw meats as well as some fermented foods, etc., since coliforms are regularly found in and/or on these foods. The presence of Escherichia coli in food is indicative of direct or indirect contamination of the food product with fecal material, thus, enteric pathogens may also be present. The presence may be indicative of inadequate processing, post processing contamination and poor sanitation.	Applicable to: Coliforms, E. coli testing
<1000 CFU/gram to >200, 000 CFU/gram	Total gram negative (TGN) count has the same significance as presence of coliforms. Elevated TGN count should not be detected in cooked or processed ready-to-eat foods. Absence of gram negative organisms in a food sample is another indicator of food safety.	Applicable to: total gram negative testing
<10 to >150,000 CFU/gram	The presence of yeast and moulds can cause various degrees of deterioration and decomposition of food, resulting in abnormal odours, flavours and colours. Both yeast and mould can also be added intentionally to a product for a desirable flavour such as mould for blue and brie cheeses and yeast for beer, ciders and wines.	Applicable to: yeast and mould testing
Not Detected / Detected	The organism should be absent in ready to eat foods.	Applicable to: Campylobacter spp., E. coli O157:H7, Listeria monocytogenes, Salmonella spp., Shigella spp., Vibrio spp. and Yersinia enterocolitica testing.

The following table provides possible test results with associated interpretations for food testing (molecular):

Result	Interpretation	Comments
Not Detected	DNA was not detected by RT-PCR.	Applicable to: Listeria monocytogenes PCR*, Salmonella spp. testing PCR.
Indeterminate	Unable to report the RT-PCR test result (no internal positive control detected and/or no target specific signal detected). Refer to culture.	Applicable to: Listeria monocytogenes PCR*, Salmonella spp. testing PCR.
Detected	DNA was detected by RT-PCR. Confirmation of the viability of the organism will be determined by culture for RT-PCR positive (reported as ‘Detected’) or questionable/ indeterminate test results (reported as ‘Refer to Culture’). Refer to culture.	Applicable to: Listeria monocytogenes PCR*, Salmonella spp. testing PCR.

Refer to the Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing for interpretation on pH, phosphatase, water activity, staphylococcal enterotoxin, and all other analyses mentioned above.

Reporting

Results are reported to the submitter (e.g., Board of Health) as indicated on the requisition.

References

Public Health Ontario. Public Health Inspector’s Guide to Environmental Microbiology Laboratory Testing [Internet]. Evergreen ed. Ontario, current version. Available from: Public Health Inspectors Guide | Public Health Ontario
Health Canada, Health Products and Food Branch (HPFB). The compendium of analytical methods [Internet]. Evergreen ed. Ottawa, ON: Government of Canada; current version. Available from: https://www.canada.ca/en/health-canada/services/food-nutrition/research-programs-analytical-methods/analytical-methods/compendium-methods.html
United States Food and Drug Administration. Bacteriological analytical manual (BAM) [Internet]. Silver Spring, MD: Food and Drug Administration; current version. Available from: http://www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm