Testing cereals for mycotoxins: review and assessment of rapid test kits

Abstract

The British consumer demands quality food free from chemical and microbiological contaminants. Mycotoxins are highly toxic chemicals produced by some fungi and can be formed in many food commodities including cereals and are indicative of reduced quality. Ochratoxin A occurs in stored UK cereals and is now regarded as a likely genotoxic carcinogen. As such, it is recommended that the amount in the UK diet is reduced to the minimum that can be achieved. The European Commission is currently discussing the introduction of legislation to specify maximum allowed amounts of ochratoxin A in grain and other susceptible commodities. To detect mycotoxins in grain in order to reduce or eliminate them from the food chain requires tests which are cheap, quick and simple to carry out, reliable and with sufficient sensitivity. The HGCA commissioned a review of test kits currently available for detecting mycotoxins in cereals together with a critical appraisal of their performance to establish whether current commercial kits meet the likely future needs of the grain trade.

Discussion with suppliers and users suggest that test kits are useful in certain situations for detecting contaminated grain, especially in the absence of sophisticated analytical facilities. A positive sample is often rechecked using HPLC. However, test kits lack either the sensitivity, speed or reliability required in situations where a rapid result is essential, e.g. testing a lorry load of grain before acceptance. There is considerable scepticism, particularly amongst analysts, about their effectiveness and their failure to be universally accepted within the UK is not helped by the lack of publicly available validation data.

It is clear that the current scale of testing grain for mycotoxins by all available methods is very small in the UK. In addition, it is concluded that test kits currently on the market have only limited application for quality control of mycotoxins such as ochratoxin A. It is unclear what scale of testing will be required by the grain trade following legislation for ochratoxin A. In the interim, proper validation studies need to be carried out with selected kits. It is recommended that new tests are then developed if necessary either by modification of current products or by using alternative technology such as has proved highly successful in other fields. There is currently little guidance on sampling grain for mycotoxins other than that laid down in the EC directive for aflatoxins and there is an urgent need to develop simple and soundly-based sampling protocols for ochratoxin A.