Developing tests for detecting irradiated foods.

Scientists at the U.K. Ministry of Agriculture, Fisheries and Food (MAFF, St. Christopher House, Southwark Street, London SE1 0UD, England, U.K.) are developing and validating tests that can be used to detect foods that have received irradiation treatment before they go to market. These include such products as spices, seafood, fruits and vegetables. As part of the validation procedure, the tests are subjected to a collaborative trial conforming to an internationally recognized protocol.

Although these types of tests are not necessarily required, they would be a useful addition to the control regime and would increase public confidence in irradiation technology. Detection tests also would make possible more effective enforcement of regulations.

MAFF scientists have published the protocols for four fully-validated tests: detection of irradiated herbs and spices using thermoluminescense technology; detection of irradiated bone-containing meat using electron spin resonance spectroscopy; detection of irradiated food containing fat by using 2-alkylcyclobutanone markers; and detection of irradiated poultry meat using the Limulus Amoebocyte Lysate test in conjunction with a gram-negative bacterial count.

Other techniques have been successfully validated by international collaboration trials, including: microgel electrophoresis, which is a screening method for detecting irradiated chicken, pork and plant seed; the direct epifluorescent filter technique and aerobic plate count; and the photostimulated luminescence technique for detecting irradiated shellfish, herbs and spices.

Researchers have extended the range of foods that can be detected by the 2-alkylcyclobutanone methodology to include some low-fat foods. They've been able to identify irradiated mangoes and avocados. Work continues toward the development of a rapid dip-stick test for detecting irradiated fat-containing foods, based on Elisa technology. Another Elisa test, able to detect radiation-induced DNA base changes, has been developed for detecting irradiated shrimp and prawns.

Scientists also are extending the range of foods that can be detected by identifying evolved hydrogen. This rapid screening technique has been able to detect irradiated frozen chicken and egg shells.

Further information. Christopher Darby; phone: [phone]; fax: [phone]; email: [e-mail].