By Greg Jones and Lynneric Potter - 2 November 2020
Today’s food packaging landscape is driven by the desire to minimise
environmental impact while maximising shelf-life and presenting products attractively to the consumer.
Packaging manufacturers are rising to the challenge to achieve this, and there are a large number of novel
materials now being presented to the food industry – often with claims of similar or better performance to
traditional materials. Some manufacturers also claim that their packaging materials have an antimicrobial
effect which can extend shelf-life. As promising as they may sound, how can these claims be proven?
Independently substantiating claims
A red meat processor, working with a materials developer, wanted to understand the impact of three novel
films for potential packaging use on the microflora of red meat during retail shelf-life. The hypothesis
being that the novel films would have an inhibitory effect on the growth of microbes, ultimately extending
the shelf-life of the product. To understand clearly any microbial changes, the red meat processor
approached us to conduct an independent study on the product packaged using the novel materials.
The beef had been aged for 21 days before packing as per standard practice. Three novel materials were
used to determine if there would be a difference between formulations. These three novel films were
tested against standard skin packaging, vacuum packaging and modified atmosphere packaging (MAP) – packaging
materials commonly used in the food industry.
The analysis of microflora has traditionally relied on counting the numbers of colonies growing on agar
media which is incubated at a set temperature for a set amount of time: a cornerstone method that’s
formed the basis of microbiology for over a century. In contrast, new techniques reliant on sequencing
genetic material are less restricted. They do not select only for the organisms that can grow on the
selected media for the selected time at the selected temperature. The new methods can detect genetic
material from organisms that would not usually grow in the laboratory and thus provide a more comprehensive
picture of the total microbial population. Sequencing-based approaches also allow a finer resolution of
groups of organisms which are difficult to sub-divide using culture alone.
To determine whether or not the packaging had made a difference to the samples’ microflora, the beef
samples were studied using advanced microbial
profiling: a DNA sequencing-based analysis. This
allows huge numbers of different individual DNA sequences to be read at any one time and was performed
using the Thermo Scientific™ Ion Chef™ Food Protection Instrument and Ion GeneStudio™ Food Protection NGS
What did we find?
Results from the sequencing showed that the novel packaging had no detectable effect on the microflora of
the products, and that the only packaging type that had any effect on microflora was the MAP format.
Figure 1 illustrates this by representing each detected organism as a specific colour. MAP was the only
form of packaging that prevented the growth of Lactococcus..
The results allowed the red meat processor to
conclude that the novel film had the same effect as the current close-contact films, enabling the food
business to make future decisions on whether to use the novel film based on sound evidence.
Lynneric Potter is a food packaging specialist within the Department of Food Manufacturing Technologies at Campden BRI where she has worked since
1999. Lynneric’s main activities involve consultancy and testing of packaging materials to ensure they are fit for purpose.