New way of assessing shelf-life for chilled products
By Greg Jones - 13
E. coli, Salmonella, Listeria – we’re all aware of the ‘buzzword’ bacteria, but we pay
less attention to all the other countless species that naturally occur on our food. It’s because
background flora is often
non-pathogenic. It might be harmless to us but what effect is it having on disease-causing bacteria? Is
it competing and therefore inhibiting the pathogen's growth? Or can pathogens benefit from the presence of certain bacteria?
One aspect of determining shelf-life is the time it takes for a microorganism (e.g. a pathogen) to reach
an unacceptable level, aka its microbial specification. The relationship between naturally occurring
microflora and pathogens may, therefore, impact shelf-life. But to fully understand this impact we must
assess this interaction. So how do we do that?
What is AMP?
AMP is a powerful DNA technique used to determine the unique mix of the microorganisms (microbiome) in a
food sample without needing to culture them in a lab. When compared to traditional culturing, AMP offers
a different way to investigate the microflora in a food product. By showing ‘everything that is there’ -
not just those microbes that can be cultured - it can give more accurate data when comparing and
monitoring the proportions of individual species. We can use this data to investigate how these species
interact with each other by assessing how their abundance changes over time. View our advanced microbial
profiling (AMP) video.
Using AMP on chilled products
We are currently carrying out a project that is exploring the potential of this technology. The project
is re-evaluating microbial specifications (set limit of microbes) for a range of chilled products and
analysing the effect that naturally occurring microflora has on the growth of pathogenic microflora.
We’re currently analysing data from challenge tests of cold-smoked salmon to identify the microbial
population changes that occurred with the growth of Listeria monocytogenes. Preliminary results show a
period of microbial population flux that coincides with the onset of Listeria monocytogenes growth in this product. What this means for shelf-life of cold-smoked salmon is to be determined with further research. Next, we will track the impact of naturally occurring microflora on Clostridium botulinum in red meat as this product matures. This work will allow specifications to be set for only those organisms of concern, potentially extending shelf-life.
How will AMP impact the industry?
AMP is providing industry with a revolutionary new insight into the relationship between food and microflora – often making us question previously held beliefs about microbial behaviour. For example, a previous project carried out used AMP to contradict the idea that microflora remains static when superchilled (at -2°C) and instead found a change in microbial diversity over 14 days. Understanding this may, in turn, change the behaviour of manufacturers in how they store their products. AMP can be used for a variety of other applications, from tracing meat to where it was processed to pinpointing the exact organism responsible in a food spoilage case. Often the possible applications are limited purely by our imagination.
How else can we help?
To help you prevent the threat caused by the major pathogens, in early 2020 we’re putting on a seminar that will cover the latest detection methods and initiatives to control Campylobacter. Why not book while there’s still time?
Greg Jones, Senior microbiologist
About Greg Jones
Greg graduated with a PhD in Molecular Microbiology from Swansea University and joined Campden BRI in 2006.