Scientific tests are used to find illegal food additives

Crushed snails, anti-freeze and beet juice are some of the illegal food additives used to adulterate food and increase producers' profits, but scientific methods are being used to find additives.

Dr John Dennis of the UK Central Science Laboratory in Norwich described some of the cut-and-thrust of this battle to the Leeds audience. His group analyses foods to prove authenticity. Tampering with food products had been going on through recorded history, he said, citing brewing laws from thousands of years BC. It continued to the present day, for example with attempts to add water and sugar to orange juice concentrate.

A handy method used by 17thcentury suppliers to make stale milk look fresh involved stirring in water and crushed snails, while the British market for high-quality cheeses from Wisconsin in the 1870s collapsed when consumers found out that lard had been added to increase volume.

This, he said, was an example of how adulteration can kill markets and limit choice. "If it is not controlled, then consumer choice is restricted. People can't get the high-quality products they want. If you don't police the authenticity properly, people will start to make adulterations to increase profitability and these changes will become ever more dangerous."

Car anti-freeze added to low-quality wine to make it look like high-quality wine caused a scandal that damaged all Austrian producers and there were deaths in Spain caused by adulterated vegetable oil when fuel oil was first added then removed, leaving toxins behind in oils later sold for human consumption.

Dr Dennis cited a massive US fraud involving orange juice concentrate. From 113 million lb of orange solids at 30 cents per lb, 141 million lbs of concentrate was sold at $1.20 per lb - with sugar and water added. The fraud went on from 1978 to 1984, earning the fraudster a $25 million profit - and a prison sentence.

The newest techniques depend on looking for tell-tale ratios of isotopes of common elements such as carbon, hydrogen and oxygen.

The ratios are unique depending on the type of sugar present. These tests can tell the difference between beet- and orange-derived sugars and helped to identify adulterated concentrates from Brazil in the early 1990s.

They can be used to determine if non-grape sugars have been added in wine production or corn syrup added to honey to increase volumes. "You can never relax your guard," Dr Dennis concluded.