Minimising the risks of microbial contamination in the field – two new online training courses

Food safety consultants David Kennedy and Malcolm Laidlaw take a closer look at the microbiological risks specific to fresh produce production and a series of associated food safety outbreaks, which led to the development of the first Level 2 Food Safety Training courses for farm workers and packers.

When someone mentions a food poisoning outbreak, most people would immediately think of poorly cooked chicken on a BBQ or something similar. In the 1980s and 90s, the first culprits on most investigators hit list would be meat and dairy. Fresh produce wasn’t considered a significant risk.

This started to change in the early 2000s, when some sizable food poisoning outbreaks were linked to fresh produce consumption. Consequentially several farm assurance schemes started to address the microbiological contamination risks associated with fresh produce and retailers became aware of the risks posed, in particular with ready to eat / minimally processed crops.

Food safety outbreaks over the years

Over the past 20 years or so, there have been a significant number of food safety outbreaks that have since been associated with fresh produce. Some examples are listed below:

• 2001 – Salmonella Newport was identified in pre-prepared bagged salad and linked to 14 cases in the UK. In 2000 one person died and more than 360 were taken ill after eating contaminated lettuce that was thought to have been used by takeaways. A second salmonella outbreak linked to lettuce affected 125 people.
• 2011 – Listeria was found in melons in USA leading to 147 people being hospitalised and 33 deaths. It was found to be caused by using a washing system (that had previously washed potatoes) for the melons, without cleaning or turning the fitted disinfection system on.
• 2014 – E. coli O104:H4 outbreak, initially associated with cucumbers, was later confirmed as being from sprouted fenugreek seeds which led to 3,950 confirmed cases, 80 requiring hospitalisation and 53 deaths. Some plants used to grow the seeds that are used in sprouted seeds are often used as a fodder crop, before being allowed to grow again and set seed, which are then used for raw sprouted seed products.
• 2015 to 2018 – Listeria outbreak in the EU resulted in 54 cases of listeriosis in Australia, Finland, Sweden, Denmark, Austria, and the UK with 10 deaths. It was traced to a frozen vegetable factory in Hungary and compounded by the fact that it was often used without cooking in salads, and sandwich fillings, as well as being picked off pizzas before cooking.
• 2021 – Salmonella was found in melons, and it was concluded that there were a variety of potential sources of contamination; the most likely being that unusually high rainfall in Honduras during the harvest period resulted in sewage overflow and run-off had contaminated the water used to irrigate the melon crops. Salmonella in melons has also been found in 2023 with over 400 people ill and 6 deaths.
• 2022 – Cryptosporidium in salad caused over 100 people to fall ill in Sweden.
• 2023 – E. coli was traced back to diced onions that caused an outbreak in America with over 80 people becoming ill and the death of 1 person.

A different mindset is needed

When we start to look at the risks associated with fresh produce, we need to approach this with a different mindset, closer to that of a factory technical person.

Often fresh produce will be grown in open fields. There will be birds flying overhead, roosting on pylons and cables, wildlife, rodents, and insects present in the cropping environments (the focus on biodiversity and sustainability has increased the amount of wildlife on farms), not to mention what is in the soil, from both a microbial and chemical nature. We also must bear in mind that allergens such as nut trees and celery or cereals containing gluten will be found in the vicinity of the fields.

Add in the potential weather impacts which can cause flooding of fields, brining chemical, physical and microbial contamination of the crops. Hot humid conditions can cause bacterial rots and fungal diseases to proliferate. And while these may not be a direct cause of an outbreak, they damage the crops allowing pathogens to enter the crops easier.

These issues are unlikely to go away – in fact with what we are seeing in terms of climate change and the increasing number of extreme weather events, the risks of a product being contaminated by food pathogens is increasing.

This is before we start to look at the actions of people. As the field will have limited security measures in place, trespassing is a possibility. Then, probably one of the biggest risks of all is the hygiene of harvesting staff when crops are hand harvested. How often have you thought about where you go to a toilet in a field without contaminating the crop?

The first Level 2 Food Safety Training courses specifically for fresh produce

As you can see from the above the normal way of thinking about food safety is not always relevant. To this end, Fresh Produce Training & Development joined forces with CIEH, to develop the first Level 2 Food Safety Training specifically for fresh produce. To make it even more specific, there are two different courses available – one for field staff and the other for packhouse staff.

Rather than taking an existing course and adapting it, we designed content specifically based on what staff need to know to minimise the risks from contamination in the field / packhouse. This approach means the courses cover microbiological risks from manure, animals, and water, through to staff and equipment hygiene. We look at physical risks from the raw materials (soil and stones), field debris, equipment and people. Chemical risks such as pesticides, heavy metals and cleaning chemicals are included.

We also consider the risks from allergens in the field. This can be from nut trees and previous crops, as well as staff activities.

There is also information on how to reduce the risks from these hazards. While it would be impossible to eliminate the hazard completely from the fresh produce supply chain, risk assessing prior to planting, and good hygiene controls through the crop growing and harvesting process will significantly reduce the risk of contamination of the crop.

To find out more about the Food Safety for farm workers online training courses, get in touch with our training experts. You can also find out more about Fresh Produce Training & Development by visiting our website.