Recent high-profile incidents such as the multiple Ecoli poisoning incident in Scotland and a smaller but still serious outbreak in Ireland has once again focused the spotlight on the need for simple, effective testing procedures for verifying contamination-free status on foodstuffs. Furthermore, the routine application of such QC-diagnostics is rapidly becoming a vital part of the food industry’s struggle to convince overseas markets of product quality. This need was strikingly demonstrated during the recent visit by Egyptian vets to Irish food producers as part of the attempts to re-open the Egyptian markets for Irish beef products.

 At DCU, the Biomedical and Environmental Sensor Technology (BEST) Centre has identified food diagnostics as an important future market for sensor technology, and several projects in this area have recently commenced. The aflatoxins consist of a group of coumarin-derived secondary metabolites of fungi which are produced by Aspergillus flavus and Aspergillus parasiticus. Some examples of their structures are shown in Figure 1. Aflatoxin exposure to humans can occur from direct, but mainly indirect, exposure. The latter occurs through consumption of contaminated foodstuffs such as cereals (and food products derived from them), nuts and milk.

 In this project, we are combining expertise in the Schools of Biological, Physical and Chemical Sciences to develop rapid screening tests for the detection and quantification of aflatoxin contamination in foods. We have focused on aflatoxins because of the lack of established simple and reliable diagnostic tests, and because of the predicted rapid growth in demand driven by legislation. Furthermore, the technology we intend to develop is generic in nature, and may be adapted for other important diagnostic tests in the food and other industries, by varying the antibody used, and the sample to be analysed.

Aflatoxin B₁ has been shown to be a potent carcinogen in animal studies. It is linked with the development of human hepatocellular carcinoma. It is regarded as a human carcinogen by the International Agency for Research on Cancer. Toxicity for aflatoxins occurs at very low levels and aflatoxin B₁, for example, at concentrations of parts per billion can cause very damaging effects. Increasingly, many foodstuffs must be shown to be aflatoxin-free at very low levels (below 0.5 ug/kg for M1 in milk and 5.0 ug/kg for B1 in animal feeds). Indeed, the EU has lagged behind the US in relation to developing regulations and rapid testing methods for aflatoxins. However, in many EU countries, e.g. the Netherlands, testing of milk for aflatoxin contamination regularly occurs (particularly M₁) and such stringency will become the norm in the next few years for all countries. In Ireland, aflatoxin analysis in milk, milk powder and animal feeds is carried out at the State Laboratory by Dr. Paula Shearan

Given the strategic importance of the food industry to the National economy, the development and application of novel diagnostic tests for ensuring food quality is of major concern to Ireland. Furthermore, it is important for Ireland to lead Europe in this type of research, rather than to follow.

At present, aflatoxin analysis is carried out at the Irish State Laboratory using an ELISA kit for screening M1 and B1, confirmed by HPLC (official method) with post-column derivatisation after sample clean-up. However, there are problems with the ELISA test arising from a relatively large number of false positives, which must then be verified by the expensive and laborious official method. The sensor we propose to develop would ideally replace the ELISA test. This group has the unique capability to combine experience in antibody production and handling with state-of-the-art developments in optical transducer design and fabrication.