Bacterial Pathogens and Indicators in Pasteurized Cheese – April 1, 2018 to March 31, 2021

The survey was conducted to generate baseline information on the quality and safety of pasteurized cheese sold at retail in Canada. The product types sampled under this survey included soft^{Footnote 2} cheeses with spices, single serve cheeses, pre-sliced cheeses, shredded cheeses, firm,^{Footnote 2} and hard^{Footnote 2} cheeses which are all commonly consumed by Canadians of all ages^{Footnote 3}. Unfortunately, many of these foods have been associated with recalls^{Footnote 4}, and foodborne illness outbreaks^{Footnote 5, Footnote 6, Footnote 7} and are considered to be high-risk foods^{Footnote 8}.

Contamination with bacterial pathogens can occur at any step in the food supply chain such as during production, processing, packaging, distribution and/or at retail and when consumed, their presence creates the potential for foodborne illness. In an attempt to determine the cumulative effect of each step in the food supply chain on the overall quality and safety of the food, and unique to specific surveys, samples were collected as close to the product best before date as possible.

The survey was conducted over a 3-year period from April 1, 2018 to March 31, 2021, however firm^{Footnote 2} and hard^{Footnote 2} cheeses were only collected during the last 2 years of the survey.

Samples were collected from national retail chains and local/regional grocery stores located in the following 11 major cities across Canada:

• Halifax
• Saint John or Moncton
• Quebec City
• Montreal
• Toronto
• Ottawa
• Vancouver
• Kelowna or Victoria
• Calgary
• Saskatoon
• Winnipeg

The planned number of samples to be collected from each city was based on the population of the province in which the city was located relative to the total population of Canada.

A total of 5206 pasteurized cheese samples were collected. A variety of product types were selected to represent a range of moisture content (soft^{Footnote 2}, firm^{Footnote 2} and hard^{Footnote 2} cheeses) and a varying degree of processing (blocks, sliced, shredded, grated). Of the 5206 samples collected, 1264 were soft^{Footnote 2} cheeses with spices, 1191 were shredded or grated cheeses, 1185 were pre-sliced cheese, 888 were single serve cheeses, and 678 were firm^{Footnote 2} or hard^{Footnote 2} cheeses. A sample consisted of a single or multiple consumer sized packages of the same lot weighing at least 250g. Samples were collected as close to the best before date as possible to account for the effects of storage conditions along the food chain.

All samples were tested for L. monocytogenes, Salmonella spp., S. aureus and generic E. coli. L. monocytogenes, Salmonella spp., and S. aureus are pathogenic bacteria while generic E. coli is an indicator of the overall hygienic and sanitary conditions under which the samples have been processed, stored and transported.

Samples were analyzed using analytical methods published in Health Canada's Compendium of Analytical Methods for the Microbiological Analysis of Foods^Footnote 9 that were suitable for the testing of pasteurized cheese.

The samples were assessed using criteria based on the principles of following Health Canada documents: Health Products and Food Branch Standards and Guidelines for Microbiological Safety of Foods – An Interpretive Summary^Footnote 10, Policy on Listeria monocytogenes in Ready-to-Eat Foods and the Food and Drugs Act^Footnote 11 (Section 4(1)).

No assessment guidelines had been established in Canada for the presence of Salmonella spp. in pasteurized cheese at the time of writing this report. As this bacteria is considered pathogenic to humans it's presence was assessed as unsatisfactory as it is considered to be a violation of the Food and Drugs Act^Footnote 11 Section 4(1)a.

Over 99.9% of the samples tested were found to be satisfactory. Salmonella spp. was not found in any of the samples tested. L. monocytogenes was detected in 1 sample and at a level of <5 CFU/g. S. aureus at 380 CFU/g and generic E. coli at 300 CFU/g were found in 1 sample each respectively.

Survey results are also presented by origin (table 3) and product type (table 4).

Previous Canadian^{Footnote 12} and international^{Footnote 13} studies on the microbiological quality and safety of retail pasteurized cheeses have shown results approximating those in our study. Differing prevalence rates between studies may be attributable to differences in product types tested, methodology, study design, etc.

Overall, our survey results indicate that pasteurized cheese sold in Canada are generally safe for consumption, however they can be infrequently contaminated. Consequently, as with all foods, and especially with those that are ready for consumption without further preparation or cooking, good hygienic practices are recommended for producers, retailers and consumers

All results are used to:

• inform risk management decisions
• support program design and re-design

While no illness were related to the investigative and unsatisfactory samples, these results triggered appropriate follow-up actions including:

• facility inspections
• additional sampling and testing
• removal of affected products from the marketplace

Yes. The data will be accessible on the Open Government Portal.