CRIMINALS may soon be caught if they leave their fingerprints on food, after Scottish scientists claimed a breakthrough in forensic research.

A team from Abertay University in Dundee has adapted a technique designed to pick up prints from the sticky side of adhesive tape, to detect marks on food such as apples, onions, bananas and tomatoes.

It is the first time this has been done successfully in the UK and the findings have been described as a "step forward in the fight against crime".

Dennis Gentles, a former crime scene examiner and forensic scientist at Abertay who supervised the research, explained some surfaces – such as feathers and human skin – have always been elusive to fingerprint detection.

He added: "Foods such as fruits and vegetables used to be in that category, because their surfaces vary so much – not just in their colour and texture, but in their porosity as well.

"These factors made recovering fingerprints problematic, because some techniques work on porous surfaces while others only work on non-porous surfaces. Using the right technique is important, because if you use the wrong one, it can damage the print and destroy what could have been a vital piece of evidence.

"The fact we have managed to successfully recover prints from such difficult surfaces as foods is another step forward in the fight against crime.

"It may not seem like much, but a piece of fruit might be the only surface that has been handled in a crime scene, so developing a trusted and tested technique to recover fingerprints from such surfaces is something to be valued by crime scene examiners."

Previous studies which took place in India and Slovenia had managed to recover fingerprints from food, but the research was based on chemicals which are not routinely used in the UK.

The team at Abertay worked through the 15 or so techniques recommended by the Home Office but found that when applied to foods like apples, onions and potatoes the prints produced were not of a quality to hold up in a court of law.

It was only when they modified a substance known as Powder Suspension – a thick, tar-like substance initially developed to get prints from the sticky side of adhesive tape – that they were able to garner clear marks.

Mr Gentles said: "The smooth surface of an apple is different from that of sticky tape, so such a thick substance wasn't going to produce the same results.

"So we tried altering the formulation a bit, making it more dilute than that suggested by the Home Office, and found it out-performed all the other methods we tested.

"We've shown it is possible to recover fingerprints from food and now police can gather more evidence to present in court."

The research is published in the specialist journal Crime & Justice.