A fish test to make food safer

A fish test to make food safer

A new testing method that detects pesticide residues in farmed fish will help the product meet new regulations and lead to safer food was developed by the Fraunhofer Institute for Molecular Biology and Applied Ecology IME.

Nowadays, half of all the fish we eat comes from fish farms. The problem is that these fish are increasingly being fed vegetable matter, which could lead to a build-up of residual pesticides in them. A new test shows how high the risk of contamination really is.

Aquaculture, with annual growth rates of 9%, is the fastest developing branch of the global food industry. Soaring demand has put supply strains on fish feed because stocks of ingredients such as fishmeal and fish oil are dwindling.

These ingredients are set to be replaced by crops such as soy and maize - which contain pesticides and thus increases the importance of being able to test fish bred in captivity for residues. While such tests are available for livestock such as pigs, no equivalent analysis for fish had been developed until now.

Now scientists at the Fraunhofer Institute have developed a system to test whether chemical substances accumulate in fish that are fed contaminated feed.

For their metabolism studies the researchers use water tanks that are two cubic meters in size. Into these tanks they place carp and rainbow trout each weighing 300 to 500 grams; both these freshwater fish are frequently bred in farms. To detect and identify pesticide residues and their metabolites, the team of scientists added a radiolabeled test substance to the pellet feed - a challenge for the researchers, as radiolabeled material is difficult to handle under aquatic conditions.

A powerful filtering system prevents the dissolved test substance from accumulating in the water. The researchers then test the flesh of these fish for pesticide residues using highly sensitive analytical methods which permit even the smallest quantities of a substance to be detected with certainty.

The method will be employed by pesticide companies in the wake of new European Union Rules due to come in this autumn. These will oblige every producer and importer who intends to bring a new pesticide onto the European market not only to register it but also to provide information proving it cannot accumulate in the edible parts of fish.
Source: Fraunhofer Institute for Molecular Biology and Applied Ecology IME