The workflow food microbiology labs are ready to leave behind

Foodborne illnesses, also known as food poisoning, affect millions of people worldwide every year. For most, this is little more than a day or so of feeling off, but for some, it can be far more serious, resulting in hospitalization or even death.

Protecting consumers from food contaminated by pathogens, ensuring food quality is as high as possible, and helping companies maintain their good reputations is an important role for food microbiology labs. One of the key steps, the preparation and use of culture media, is creating a barrier to timely and cost-effective work.

Food microbiology: The current testing landscape

Using the right culture media in the right concentration is a crucial part of testing for food pathogens. Broadly speaking, food microbiology labs use either dehydrated powder that is reconstituted, or ready-to use media. Dehydrated culture media is easy to store and can be prepared as needed, in exactly the volumes and formulations required. Ready-to-use and bagged media are convenient, and the ease of use reduces the likelihood of human error.

Both forms of media bring their own set of challenges, however, but many labs have stayed with these approaches, as Jaakko McVey, Senior Product & Portfolio Leader, Thermo Fisher Scientific, explains, “Food microbiology labs must remain compliant, so in order to reduce risk they may minimize change and remain with what they know works.”

Bryan De Caux, Staff Scientist, Culture Media, Thermo Fisher Scientific, adds, “It's also about the flexibility and familiarity that labs have with dehydrated media. They know how much they need to make, and they are used to working out cost based on media prices.”

The unspoken problems with operational challenges

As with all areas in commercial science, food microbiology labs are under pressure: keeping ever-rising costs under control and maintaining productivity by increasing throughput and protecting turnaround times, whilst maintaining accuracy, audit readiness, and staff safety.

“Labs perceive dehydrated culture media as a lower-cost resource, but the reality is different – there are many hidden costs,” says De Caux, who has 27 years of industry experience in microbiology and culture media.

Dehydrated culture media preparation requires a series of manual steps, including weighing, mixing, heating, sterilization, cooling, QC, cleaning, storage, and documentation. There is also the purchase, running, maintenance and replacement cost of equipment. While introducing semi-automated steps has made some improvements, the entire process is still resource intensive, time-consuming and monotonous, with every step bringing in the potential of variability or human error.

Productivity in labs is defined by variables above and beyond the time taken, according to McVey, drawing on his 25 years of experience in life sciences and diagnostics. Preparing dehydrated culture media can be a bottleneck in the whole testing process, affecting the number of samples a lab can process per week.

He explains, “We need to consider the workflow. For example, how many samples turn up on a given day? Is there an outbreak, or is the factory line shut down for cleaning or maintenance? We also need to think about the kind of working environment the workflow creates for our staff, who are highly trained in microbiology and food safety.”

Preparing media is not using the very valuable expertise the scientists and technicians have to its best extent. As well as taking up time that could be used for more specialist and value-added tasks, the monotony can mean that they become distracted and are more likely to make mistakes. Additional costs come from the use of a lot of energy and water in cleaning and cooling equipment, and in preparation and sterilizing media.

“Per cycle, a master clave uses 200 litres of water to produce 30 litres of media. Capital expenditure and space are also challenges for a lot of labs, especially when they have grown to a point where their infrastructure won’t let them grow anymore,” says McVey.

The ISO process requires media to be weighed out to a certain accuracy. Pre-preparing single-strength media in fixed, pre-dispensed volumes for common food sample sizes can save time, but it reduces flexibility because the media cannot be adjusted to the actual sample mass.

“ISO allows the food sample to be weighed within a tolerance of ±5%, but the amount of media added still needs to achieve the required dilution ratio within a tighter tolerance of around ±2%. In a typical 1:9 dilution, the required media mass is nine times the actual sample mass. Because the actual sample weight is not known until it has been weighed, a fixed pre-prepared volume of media cannot consistently achieve the required tolerance. Gravimetric diluters overcome this by calculating and dispensing the correct amount of media based on the measured sample weight,” explains De Caux.

Ready-to-use media can help reduce the bottleneck, but it has a higher cost per litre than the dehydrated form, and bulky bags or bottles have to be stored at specific temperatures. As the materials are ready made, it is harder to balance volumes ordered against fluctuating and unpredictable cycles of sample demand.

Finding a solution

When labs get food samples in, they do not want to have to say that they do not have the capacity to turn the test around. According to De Caux, “If a wave of samples come in, rather than the lab manager worrying about whether there is media on the shelf and ready to use, or whether there is the staff available, they can know that they have the media on demand and be confident that they can turn the tests around.”

Food microbiology labs are looking for approaches that help them to support their customers, reduce their costs, free up space, equipment, staff time and other resources, and make the testing process more efficient, cost effective, and better able to react quickly to demand.

Changing the way that labs source, store, and use culture media could make a major difference to all these needs, but it is important to remember that a new workflow must introduce net benefits and ideally be cost-neutral compared with existing approaches:

• Available on demand and dispensed at the correct mass (for gravimetric methods) and media strength (when using concentrates) to manage variable day-to-day testing requirements
• Simple to store, with a long life in storage and then a usable bench shelf life after preparation
• Automated to reduce manual preparation steps, save time, improve flexibility, and increase consistency, releasing staff to take on more skilled tasks
• Include connectivity to send data directly to the LIMS system, linking samples with media type, strength, batch, relevant mass data, and other preparation parameters, thereby improving traceability and transparency
• Take up less space than existing approaches, in storage, in preparation, and in use
• Use less water and energy compared with traditional approaches
• Create as little waste as possible, for example reducing plastic consumption
• Meet the needs of a tightly controlled and regulatorily compliant workflow

The next era of food microbiology needs to be about more than iterative changes to automation, or different ways to culture package media. It must rethink the entire process to focus on flexibility, productivity, and efficiency. This can be achieved by making faster and simpler media production an integral part of the testing process.