If you make it, somebody else will fake it.

From designer handbags to hair straighteners, there is always a cloned rip-off available, not least at this time of year.

There is a fairly good chance that one of the presents you unwrapped on Christmas morning was fake. Most people know this. After all, trading standards have been issuing seasonal warnings about “passing off” for years

What we are perhaps less aware of is that your Christmas dinner may not quite be what you thought. Those chocolates? Can you be sure they are fair trade or organic? After all, the mark-up on a sustainable product can be huge. Researchers earlier this winter made specific warnings about the global trade in cocoa.

This year there was even a British fake turkey scandal. True, it was about two criminals passing off turkey mince as lamb to restaurants. They were jailed for five years.

Food fraud is big business. There are estimates suggesting that 10 per cent of the global supply chain is affected. That is £50 billion worth of produce. Britain - and the rest of the European Union - has not been immune, despite a much tougher regulatory regime than in, say, Asia.

Major retailers and manufacturers four years ago admitted they had unwittingly put horsemeat in some of their frozen beef dishes, such as lasagne.

That scandal sparked an industry-wide panic and a huge loss in consumer confidence.

Firms producing premium products feel most at risk. Large animals, like sheep and cows, can be electronically tagged. But how do you know for sure that a fish or chicken you are eating comes from where you think?

Well, the answer might just lie in forensic science. Several firms have been working on technology that will enable them to check the flesh of an animal to see where it was reared.

The theory is that there will be telltale signs of locality, even the minerals in the grass cows eat or in the sea where fish are caught or farmed. Scientists can use spectrometry to produce a molecular fingerprint of the flesh of a fish, or at least of the smoke that comes off it when it is singed.

And that is before the ultimate test: DNA. Such technology is expensive. Right now only premium producers are using it to protect their bands from fakes.

Loch Duart has become the first salmon producer to fingerprint its fish. The farming firm, which trades on its reputation for quality and sustainability, had become aware that wholesalers were passing off fish as Loch Duart when they were from elsewhere.

They may have reason to be concerned. This year a company director was fined £200,000 and given a community sentence for fraudulently changing the labels on salmon destined for export.

Alban Denton, Managing Director of Loch Duart, said: “We are really proud of our extraordinary tasting salmon which is asked for by name worldwide. If another salmon is ‘passed off’ as ours, consumers are being both exploited and misled. Our distributors have told us that it happens.”