Listeria monocytogenes is considered the number one food safety hazard in dairy processing. In 2013 in Australia, there was a large outbreak of listeriosis from mould-ripened cheeses, which was linked to 34 illnesses and 7 deaths, including 1 miscarriage.

Understanding and managing the risks associated with listeria are critical for dairy processors.

“Food safety audits have highlighted significant inconsistency with risk analysis and management, including that associated with managing the listeria hazard. Dairy processors are not necessarily well served with information to assist in understanding the mitigation strategies for managing the risk of listeria in dairy manufacture,” said Geoff Raven, CEO of Dairysafe.

“The Dairysafe Board has recognised this as a gap and has endorsed the delivery of free workshops for dairy processors on managing listeria in June, which every dairy processor should have staff attend.”

How does listeria develop?

Listeria can be introduced into the production facility by products or ingredients that that haven’t received an adequate microbial kill step. Raw milk may contain listeria and so segregation of raw and processed products is critically important to prevent possible cross-contamination.

Ingredients that are not heat-treated, or are added after pasteurisation, are potential hazards and so it’s important these are purchased from suppliers that can provide an assurance the products are free of listeria.

Additionally, handling ingredients and packaging can be potential sources of contamination, which is why every dairy processor is required to have detailed arrangements for pre-requisite programs such as hygiene, storage and cleaning (GHP and GMP).

Listeria prevention

Although regular product testing results may show an excellent history with respect to indicator organisms such as coliforms, Enterobacteriaceae or staphylococci, testing for these organisms will usually provide no indication that Listeria may be present in the plant or product. Listeria species often live and breed in different environments to these other contaminants. They are widespread in the general environment in soil and water and can be carried by animals. They are most commonly found in moist damp environments, and are hardy survivors.” DFSV Technical Information Note, 2013

All members of your staff are critically important in protecting your product and business from the risk of listeria.

Are they adequately trained in hygienic practices relating to their job? The best of systems and equipment does not eliminate the risk of contamination if your people do not understand how contamination can occur.

Have you sought out other information, resources and training to ensure your staff and business are fully capable of managing listeria?

Due to the high mortality rate (~30%) and absence of a ‘kill step’, due to the listeria risk occurring in post-processing, it is generally accepted that this is the major risk to the dairy industry.

There are various strategies that can be adopted to help prevent listeria contaminations occurring. These include: implementing an environmental monitoring program, designing the manufacturing plant to reduce the risk of contamination and improving operational aspects or processes within production.” (DFSV Technical Information Note, 2013).

Dairysafe’s approach to assisting industry manage the risk of Listeria in dairy processing has three key pillars:

  • Promoting arrangements that mitigate the risk of listeria directly to dairy processors at industry workshops – coming in June;
  • Developing comprehensive guidelines for dairy processors on how to manage the risk of listeria – in development; and
  • Reviewing and verifying listeria management arrangements at each dairy processor during audits – scheduled for the second half of 2021.