Food provenancing – the forensic traceability of food and drink

This weekend at the crimeScene conference I attended several forensic science sessions along with some fascinating sessions on writing science and accurately conveying the story of science. Most of the sessions related to murders and murder mysteries (OK, guilty pleasure). However, one very interesting session was on food forensics.

Winthrop Professor John Watling from UWA’s Centre for Forensic Science gave a very enlightening talk about the techniques they’ve developed to trace the origin or provenance of food. Australian agriculture has a good international reputation – we’re clean and green – and so sometimes products in other countries get labelled as Australian even when they aren’t. They can command a better market price that way. But it’s not just other countries – there’s an estimated $18 billion of food fraud each year in Australia itself. That’s around 30% of your average supermarket basket each week. Current traceability of food depends on bits of paper – labels, packaging stamps, receipts – and most of it is easily forged or otherwise intercepted. To securely identify food and keep the integrity of the supply chain you need something that can’t be changed – and that something is the food itself.

Every farm, every vinyard, every fishing area has unique conditions. Their soil, rainfall, distance from coast, climate, position on a continent all vary. That leads to tiny, tiny differences in trace elements and ratios of isotopes in some elements. This used to be difficult to measure, but nowadays there are 70 different elements that can be measured accurately to one part per trillion in just one minute. This gives an enormous range of possible chemical signatures, and the speed means you can test four to five hundred samples overnight. Different foodstuffs go through different biochemical pathways as they grow, they can’t all be tested exactly the same way, but the Forensic and Analytical Chemistry Group that’s working on food forensics has developed processes now for testing 67 different foodstuffs and tracing them back in many cases as far as farm-of-origin. Not just country, or state, or general region, but often individual farms.

During the session Prof. Watling mentioned twelve different foodstuffs they’ve worked on, including some they’re still developing processes for but have made some headway. Pork was a big one – adulteration or relabelling of products overseas (to take advantage of the “Australian” brand) led to them developing a database of pork signatures. They can now take a pork chop from a supermarket and identify its farm of origin in just 18 hours. They’re extending this work to include pig offal as well. Wine was another important one, with counterfeit “Australian” wines being sold that had never touched Australian soil. So they built a wine database. Blended wine (a common and legal practice) offered some difficulties and still does, but they can still identify a blend of up to three wines. Tea and coffee are all able to be traced back to continent and country of origin and even estate or garden of origin which allows checking of “fair trade” labels and stated provenances. Prawns are one of the foods currently under investigation, and just in the last couple of months they’ve developed the process to where they can identify whether a prawn came from the sea, an estuary or an aquaculture farm, but work is continuing. Barramundi and abalone are also in progress. A process for chocolate is in preliminary stages, to be used both for fair trade and to help companies avoid those plantations where child labour is used. And there were many more.

The one that most interested me – and is most topical I think – was eggs. They’ve developed datasets that allow them to tell if any egg they test is barn-laid, free-range or a cage egg. That work was new at the time of this conference last year, but since has become fairly well known and has now led to its first conviction for selling cage eggs as “free-range”. I had noticed over the last few months that I wasn’t seeing as many free-range eggs on the supermarket shelves, and that the free-range shelves were empty a lot more often. The development of this process is part of the reason why. Some farms that were previously offering free-range eggs as part of their line have now switched to selling cage eggs only, and the supply of free-range eggs has dropped dramatically.

Edited at 9:15 Perth time to reflect more accurately the limits of the processes and their influence.

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