Category Archives: Microbiological Risk Assessment

Research – Evaluation of sodium hypochlorite and peroxyacetic acid to prevent transfer of surface‐attached Listeria monocytogenes to produce

Wiley Online


Sporadic contamination of produce with Listeria monocytogenes (Lm) is a recurrent problem. Ways for contamination to occur include transfer of the pathogen to produce from processing surfaces or soil particles to which it has become attached. Since it is known that surface‐attached Lm is less susceptible to antimicrobials than Lm grown in liquid culture, the goal of the current study was to determine if Lm grown on surfaces and released into water retained its higher tolerance of antimicrobials. In addition, transfer of Lm from surfaces or soil particles to blueberries, mung beans and spinach leaves in the presence of the antimicrobials, sodium hypochlorite (NaOCl) adjusted to pH 6.8 and peroxyacetic acid (PAA), was studied. The experiments were carried out with a cocktail of six Lm strains and strains obtained from produce processing plants. Results indicated that Lm released from surfaces was as susceptible to the two antimicrobials as Lm grown in liquid culture and was inactivated within seconds by an initial concentration of 100 ppm of NaOCl or PAA. Transfer of Lm grown on stainless steel coupons to blueberries in wash water was not observed at NaOCl concentrations as low as 20 ppm. In contrast, transfer of Lm from washed soil particles (COD = 1.7 ± 0.89 mg/l) in contact with mung beans was observed even at initial NaOCl or PAA concentrations of 250 ppm. Lm released from washed soil particles to which it was attached to spinach leaves could be detected in the presences of 20 ppm of NaOCl and PAA and occasionally even in the presence of 100 and 250 ppm of the antimicrobials.

Canada – Harvest brand Polish Sausages may be unsafe due to undercooking


Recall details

Ottawa, January 14, 2021 – Harvest Meats is recalling Harvest brand Polish Sausages from the marketplace due to undercooking. Consumers should not consume the recalled product described below.

Recalled product

Brand Product Size UPC Codes
Harvest Polish Sausages 675 g 0 57393 70017 8 BEST BEFORE 2021MR15

What you should do

Check to see if you have the recalled product in your home. Recalled products should be thrown out or returned to the store where they were purchased.

Undercooked food may contain bacterial pathogens which can make you sick.


This recall was triggered by the company. The Canadian Food Inspection Agency (CFIA) is conducting a food safety investigation, which may lead to the recall of other products. If other high-risk products are recalled, the CFIA will notify the public through updated Food Recall Warnings.

The CFIA is verifying that industry is removing the recalled product from the marketplace.


There have been no reported illnesses associated with the consumption of this product.

Product photos

Printer ready version of photos

  • Harvest – Polish Sausages – 675 grams (front)
  • Harvest – Polish Sausages – 675 grams (back)

Public enquiries and media

Company information
Harvest Meats: 1-800-667-1496 ext. 358
Public enquiries
Toll-free: 1-800-442-2342 (Canada and U.S.)
Telephone: 1-613-773-2342 (local or international)
Media relations
Telephone: 613-773-6600

Research – Possibility, duration, and molecular predictors of sanitizer tolerance in Listeria monocytogenes

Centre For Produce Safety


Due to concerns over bacterial tolerance to sanitizers, FDA and FSIS recommend rotating sanitizers in RTE food processing facilities to better control foodborne pathogens, in particular, Listeria monocytogenes (Lm). These recommendations are nonbinding; whether Lm develops tolerance to common sanitizers remains
inconclusive and debated. Even if Lm develops tolerance through sub-lethal exposure to sanitizers, how long and how strong the tolerance can last should be considered in determining whether sanitizer rotation is needed and how often it should be applied. Lack of consensus and quantitative data on possibility and duration of sanitizer tolerance creates confusions and dilemmas, especially when sanitizer rotation presents considerable challenges in training, compliance, and cost control to the industry. This proposal describes studies to help settle the debate and fill critical knowledge gaps regarding Lm tolerance to chlorine and quaternary ammonium compounds. We will measure residual sanitizer levels in produce processing facilities. We will perform laboratory assays to investigate tolerance development and persistence. We will explore machine-learning-aided tolerance prediction and identify evolutionary signals (or lack thereof) of tolerance development from whole genome sequencing data. Our results will provide the industry and regulators with scientific evidence for substantiating, better implementing, or justifiably shelving sanitizer rotational programs.

Technical Abstract

There is still no scientific consensus on whether Listeria monocytogenes (Lm) develops sanitizer tolerance. We hypothesize that development of two types of sanitizer tolerance may occur in Lm. First, short-term adaptation to sub-lethal levels of sanitizers induces acquired tolerance, which is transient and not hereditary. Second, long- term selection by sanitizers causes intrinsic tolerance, which is established in Lm populations by evolutionary changes to Lm genomes. To help settle the debate, we will test our hypothesis by distinguishing and investigating both types of tolerance in Lm using chlorine and a quaternary ammonium compound as example sanitizers.

In this study, we will survey residual sanitizer levels in a leafy green and a tomato processing facilities to evaluate if laboratory-derived sanitizer levels optimal for tolerance development are relevant to produce processors. We will assess the possibility of acquired tolerance by measuring the difference in minimum inhibition concentrations (MIC) before and after sanitizer adaptation. We will study how different sanitizer levels and exposure time affect the development of acquired tolerance, including how long the tolerance can last after exposure to sanitizers. We will explore the mechanisms behind the development of acquired sanitizer tolerance by characterizing temporal shifts in Lm transcriptome throughout the duration of the tolerance.

We will assess intrinsic tolerance in a collection of 200-300 strategically selected Lm strains using high-throughput growth kinetics assays. We will search for evolutionary evidence that suggests the development of intrinsic tolerance in recent history by analyzing whole genome sequencing (WGS) data of these strains. We
will build a machine-learning classifier to predict tolerance levels and identify key tolerance predictors from WGS.

This research will provide valuable prerequisite information for determining if sanitizer rotation is necessary for preventing the development of Lm tolerance to sanitizers. Scientific data from the project will also help optimize sanitation practices to mitigate tolerance development and determine frequency for sanitizer rotation if rotation is needed.

USA – 5 Ways to Prevent Salmonella from Backyard Chickens

Wide Open Pets


More and more people are getting Salmonella from backyard chickens. Are you at risk?

This year there were more cases of Salmonella linked to backyard chickens than ever before recorded by the Centers for Disease Control and Prevention (CDC). In fact, there were over ten Salmonella outbreaks, and 1,100 cases in 48 states just this year so far!

We’ll tell you what Salmonella is, help you figure out if you’re at risk, and let you know the best practices for how to stay healthy. Having backyard chickens is fun, but getting Salmonella definitely isn’t!

CDC Report

Research – Exploring food safety perceptions and self-reported practices of pet owners, providing raw meat-based diets to pets.

Journal of Food Protection

The growing popularity of raw meat-based diets for pets is accompanied by an increasing concern regarding possible health implications of this practice to pet owners, due to the storage and preparation of raw meat. This study aimed to explore pet owners’ knowledge and perceptions about safety of raw meat-based feeding and determine self-reported food safety practices during raw meat-based pet food preparation. An online questionnaire was distributed via social media platforms was completed by pet owners practicing raw meat-based feeding ( n =174). Almost all participants (95%) reported confidence that their pets’ raw meat-based food is safe. Two thirds of respondents (67%) reported to have researched food safety information, regarding raw meat-based feeding, however only 8% asked a veterinarian for food safety advice. Respondents were aware of pathogens that may be present in raw meat-based diets, and of food safety practices, however, they did not report implementation of appropriate food safety practices consistently. Malpractices, such as rinsing raw meat (27%) and lack of segregation (52%) were reported. The risk of foodborne illness to pet owners associated with raw meat-based feeding was perceived to be ‘low’ by 89% of pet owners. Participants perceived low susceptibility to foodborne illness, but high self-efficacy, which may be an indication of ‘optimistic bias’. This study has identified the need for increasing pet owners’ awareness of the possible risks associated with raw meat-based feeding to human health. The provision of comprehensive food safety information, intended to target the perceptions of pet owners identified in this study, is needed to improve pet owners’ food safety practices, to reduce the potential food safety risks associated with raw meat preparation and storage in the domestic environment.

Norway – The Norwegian Food Safety Authority with an inspection campaign on Listeria measures in salmon slaughterhouses


In 2021, the Norwegian Food Safety Authority will carry out an inspection campaign in all salmon slaughterhouses where we will investigate measures and routines to prevent the fish from becoming contaminated with the listeria bacterium.

Listeria monocytogenes can cause listeriosis. Most of us do not get sick from the bacterium, but pregnant women, children, the elderly and people with weakened immune systems are vulnerable. Listeria multiplies at cooling temperature, survives freezing, salting and smoking, but is killed by adequate heat treatment.

– Since salmon and aura are largely eaten without heat treatment and used for ready-to-eat products such as sushi, sashimi, smoked and digged fish, it is important that producers have effective measures against Listeria, says Elisabeth Wilmann, director of fish and seafood at the Norwegian Food Safety Authority.

Several listeriosis outbreaks in EU countries a few years ago

In 2018 and 2019, there were serious outbreaks of listeriosis in several EU countries related to the consumption of smoked, grated and marinated fish products. The raw materials were Norwegian salmon and aura. The product was traced back to processing plants in Poland and Estonia, but one could not rule out that the raw materials from Norway were contaminated.

– The fact that Norwegian salmon and aura have been linked to serious disease outbreaks is one of the reasons why the Norwegian Food Safety Authority is carrying out the inspection campaign. Another reason is that more and more countries are making demands with regard to Listeria in Norwegian fish, Wilmann says.

The Norwegian Food Safety Authority’s experience is that Norwegian salmon slaughterhouses generally have good knowledge of microbiological hazards in fish, and that targeted work has been done on measures against Listeria.

– At the same time, we know that Listeria is regularly detected in the production environment in Norwegian slaughterhouses, says Wilmann.

The Norwegian Food Safety Authority will guide, clarify responsibilities and get an overview

In the campaign, the Norwegian Food Safety Authority will examine the slaughterhouse’s measures, sampling and routines for non-conformance treatment.

– We emphasize guidance. In addition, we will clarify the regulations and the responsibility of the slaughterhouse to prevent unsafe products from entering the market, says Wilmann.

The aim is to control all salmon slaughterhouses and vessels that slaughter salmonids. The campaign period is 15 January to 1 September, and the final report will be published towards the end of 2021. It may be relevant to carry out some of the inspections digitally due to coronary restrictions.

In 2020-2021, the Norwegian Food Safety Authority will also implement a monitoring and mapping program to map the status of Listeria.

– By obtaining a better overview of the status of Listeria in salmonids, we will be in a better position to contribute to the clarification of any future disease outbreaks, Wilmann concludes.

Read more on the website for the supervision campaign

Research – Validation of simulated commercial manufacturing of flour tortillas to control Salmonella contamination

Wiley Online


This study validated a typical batch commercial flour tortilla cooking process against Salmonella contamination. Tortilla dough prepared from flour inoculated with a 7‐serovar Salmonella cocktail was pressed in a dough press (preset at 200 °F [93.3°C]) for 3 s, then heated on a griddle (preheated to 221.1°C [430 °F]) for 30, 45 or 60 s on each side, followed by ~8 min of ambient air cooling. The maximum internal temperature of tortillas during cooking was >97°C for all cooking times. The Salmonella counts in tortillas decreased >6‐log at all cooking times; however, tortillas cooked for 30 and 45 s had an undercooked appearance. The water activity and pH of cooked tortillas after 60 s of heating on both sides followed by cooling were 0.934 and 6.62, respectively. The D‐values of the Salmonella cocktail in raw tortilla dough were 22.2, 13.4, and 4.6 min at 55, 58, and 61°C, respectively, and the z‐value was 8.9°C.

Research – The use of antifungal oat‐sourdough lactic acid bacteria to improve safety and technological functionalities of the supplemented wheat bread

Wiley Online

In the present study, predominant lactic acid bacteria (LAB) were isolated from oat sourdough. Then, the isolates were screened based on their in vitro antifungal activity. Subsequently, biotechnological capabilities of the selected LAB were evaluated in wheat bread supplemented with controlled fermented oat containing the isolate. Pediococcus pentosaceus was molecular identified as predominant antifungal isolate. Based on our results, fermented oat not only significantly (p < .05) reduced the mold expansion on the produced breads, but also improved the quality attributes of the product. Crumb porosity and antioxidant capacity of the supplemented bread revealed the positive effects of the isolate on textural and functional characteristics of the enriched bread. Wheat bread supplemented with controlled fermented oat had also the highest 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity compared to the other samples. Accordingly, the potential applications of Ppentosaceus isolate as profunctional starter culture in processing of mixed wheat‐oat sourdough bread were verified.

Research – Photocatalytically Enhanced Inactivation of Internalized Pathogenic Bacteria in Fresh Produce using Ultraviolet Irradiation with Nano-titanium Dioxide

Journal of Food Protection

Once pathogens are internalized in fresh produce, they pose a challenging food safety issue since they are not effectively inactivated by conventional rinsing or sanitization. To protect food safety and public health, the objectives were to examine internalized levels of foodborne pathogens in different types of fresh produce and to investigate the effectiveness of photocatalytically enhanced inactivation of internalized pathogens in fresh produce using UV irradiation with titanium dioxide (TiO 2 ). For this, green fluorescent protein-labeled S. Typhimurium and E. coli O157:H7 were inoculated on the leaf surface of four types of fresh produce (~10 8 CFU (colony-forming unit)/leaf) and varying concentrations of TiO 2 suspension (0.50, 0.75, 1.00, 1.25, and 1.50 µg/ml)) were applied to the surface of contaminated leaves. Depending on the nature of each vegetable, the internalized bacterial level differed (log 2 – 5 CFU/g of leaf). When UV irradiation (6,000 J/m 2 ) was applied, the internalized S. Typhimurium and E. coli levels were reduced by 0.8 – 2.4 log CFU/leaf and was with TiO 2 , the reduction was 1.1 – 3.7 log CFU/leaf. The inactivation efficiency increased as the TiO 2 concentration (up to 1.50 μg/leaf). These results indicate that the TiO 2 application enhanced the photocatalytic inactivation of internalized foodborne pathogens. The application of TiO2 would be most practical before UV irradiation and before distributing the produce. This study established a platform for future research on the inactivation of various internalized pathogens for protecting public health and scaling up fresh produce treatments by the food industry.

Research – Tech developed to detect food poisoning in real-time

Korea Biomed

The Korea Food Research Institute (KFRI) said Wednesday its researchers have developed a technology to manage food-poisoning bacteria in food materials safely in variable temperature environments of the food supply chain, such as storage and distribution.

KFRI’s “dynamic prediction model” can predict the proliferation of food poisoning and contamination of food supplies in real-time using the Internet of Things by linking the temperature provided by the food supply network.

Most of the food ingredients in group meals are safe. Still, some food products contaminated with food poisoning bacteria may increase due to temperature changes during the distribution-storage process. This explains why real-time safety management technology is needed in the process, KFRI said in a news release.