Most common forms of adulteration include the mixing of cheaper alternatives in products such as fruit juice. Bogus and contaminated ingredients can be costly to the industry and an adequate and efficient way of testing for contamination is important.

Bilberry extract has seen one of the biggest adulteration problems and techniques to detect whether it has been mixed with other components, including red dye 2, have been developed. Some cheaper extracts masquerading as bilberry were found to contain mulberry or black bean skin by scientists last May.

To help confirm the authenticity of food, scientists at the Department of Analytical Chemistry at the Spanish university are trying to identify a family of chemical compounds naturally present in fruit known as polyphenols.

They are working on the basis that different fruits have specific polyphenol counts.

These polyphenols are analysed by a high-performance liquid chromatography technique (HPLC). Oranges, mandarin, lemon, grapefruit and a dozen other fruit grown in Spain were studied. The polyphenols were counted and compared, and a fingerprint built up.

Now the researchers hope to use their fingerprints on existing commercial juices on the market.

The industry has been looking at ways to test for adulteration, especially in the wake of the bilberry crisis. Last month the American Herbal Products Association (AHPA) launched a toolbox designed to help determine whether powdered bilberry extract is contaminated.

AHPA said it will provide analytical tools and methods to identify the adulteration of raw materials labelled as bilberry extract. This, the group says, will make it easier for industry to make wise purchasing decisions and detect the presence of the banned red dye 2.

The scale of the bilberry situation reached such proportions that Japan, currently the biggest market for the extract, considered banning bilberry.

Companies were advised to test their bilberry extracts independently, especially if they were purchased for less than €500 per kg. Pricing levels are understood to have decreased since that advice was issued in May.