Better food protection on the way


DNA-infused patch signals the presence of pathogens, offering better safety for consumers. Andrew Masterson reports.


Researchers Hanie Yousefi and Tohid Didar examine a transparent patch which can be used in food packaging to detect pathogens.
Researchers Hanie Yousefi and Tohid Didar examine a transparent patch which can be used in food packaging to detect pathogens.
McMaster University

The ubiquity of “best before” labelling on packaged foods may be coming to an end, with the development of a patch that can signal the presence of harmful bugs.

Recommended use-by dates are in one sense an exercise in estimation. The advice that any particular food is safe to eat until a specific calendar date rests on several assumptions – that the item has been kept in optimal conditions, for instance, that it has not been tampered with, and that the hygiene protocols throughout the chain of production were observed.

The sad fact that there are more than 93.8 million cases of gastroenteritis caused by salmonella worldwide every year is a clear indication that those assumptions are prone to failure.

Now, however, scientists at McMaster University in Canada have demonstrated a proof-of-concept packaging hack that means consumers can abandon a calculate-and-hope approach to food safety and rely instead on direct and immediate evidence.

In a paper published in the journal ACS Nano, a team of chemical engineers and nano-science researchers reveal the development of a transparent test patch made from bioactive paper than can be incorporated directly into food packaging.

The patch is impregnated with DNA molecules that act as sensors, primed to detect the presence of pathogens such as salmonella and Escherischia coli, two of the leading causes of food poisoning.

Consumers can test for the presence of the bad guys by simply running a mobile phone – equipped with an appropriate app-based reader – over the packaging and checking the information relayed.

“In the future, if you go to a store and you want to be sure the meat you're buying is safe at any point before you use it, you'll have a much more reliable way than the expiration date,” says lead author Hanie Yousefi.

While only at test stage at present, the researchers say the patch could easily be scaled up to mass production and incorporated by food producers in to packaging without significantly affecting production costs.

When you consider that for manufacturers the end-result of being found responsible for food poisoning outbreaks often include bankruptcy and prosecution, the Canadian patches might even be considered prudent investments.

  1. https://academic.oup.com/cid/article/50/6/882/419872
  2. https://pubs.acs.org/journal/ancac3
  3. https://pubs.acs.org/journal/ancac3
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