Sampling is one of the most problematic aspects of GMO testing. The reason for this is that unexpected GM content tends to be distributed unevenly. Whether it's a field of crops, a shipment of grain, or a container of flour, GMOs in any test lot are usually clustered in isolated hot-spots. Most parts might be GMO free, while other parts can have very high levels of unexpected GM presence. If authorities take only a small amount of material back to the lab for testing, they could easily miss the GMOs.
It doesn't suffice, however, to only find out how extensively to sample. Finding out where to sample is a case of working smart instead of working hard. For example, a container of rapeseed oil from one supplier may have high GM content, while another container may be below the labelling threshold. If they are mixed, the entire batch would require labelling, which could reduce the value of the final product. Therefore, it might be wise to test products before different shipments are mixed together.
The best way to address sampling challenges would be to come up with optimised protocols that are standard throughout the EU. With the help of statistical tools, Co-Extra researchers will optimise sampling plans for seeds, grains, ingredients, and final food products. Once these protocols are finalised, GMO testing will be more reliable and reproducible.
Some products undergo processing steps that destroy evidence of GM content. Soy lecithin and refined vegetable oil, which are often derived from GMOs, are used in countless foods, but processing steps subject them to such extreme temperatures and pressures that most of the DNA is destroyed. Without enough DNA for analysis, testing for GMOs is virtually impossible. Researchers are now developing higher performance DNA extraction techniques to enable GMO testing for ingredients like refined oil and lecithin.
Substances in plants and foods slowly break down over time. The molecules that are targeted by GMO tests are no exception. Considering the fact that not all strands of DNA are created equal, there is evidence suggesting different genes are degraded at different rates with age and processing. Therefore, Co-Extra researchers are checking samples to see if test results for the percentage of GM content vary as a product ages and undergoes processing. With this knowledge in hand, stakeholders will be able to obtain protocols that minimise testing inaccuracy due to sample degradation.