Using electrons to treat organic seeds

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Fraunhofer FEP

Whereas a few years ago, organic products were sold exclusively by small health-food stores, they can now be found in the majority of supermarkets. A growing number of consumers prefer to buy organic food that has been grown without the use of chemical pesticides. Conventional farming practice involves treating seeds with a mixture of chemicals: Fungicides to protect the emerging seedlings from attack by microscopic fungi, insecticides against wireworms, aphids and biting insects, herbicides to suppress weeds. Researchers at the Fraunhofer Institute for Electron Beam and Plasma Technology FEP in Dresden have developed an alternative to fungicide treatment. "If cereal crops succumb to disease, this is usually due to microscopic fungi and spores present on the outer surface and in the husk of the seeds. Instead of using chemical products to eradicate these spores, we make use of accelerated electrons," says FEP team leader Dr. Olaf Röder. So what happens when the electrons hit the seeds? "It's not unlike cooking. For instance, when you make strawberry jam, the germs are killed by the high temperature – and your jam will keep for years. The electrons destroy the chemical bonds that hold together the molecules in the fungal spores and other pathogens, but without generating heat. You might say that they cause the molecules to explode," explains Röder. The plant developed by the researchers exposes the seed to electrons as it falls through the treatment zone. It is capable of treating 30 metric tons of seeds per hour – or disinfecting the entire surface of around 200,000 individual seeds per second. But the greatest challenge is not the speed of the process: "Plant seeds are living organisms. If we damage the plant embryo, the seed will not germinate. We therefore have to dose the energy of the electrons very precisely, to ensure that they penetrate no further than the outer layers of the seed," says Röder.

The researchers are disinfecting around 5,000 metric tons of seeds per year in collaboration with seed growers Schmidt-Seeger-GmbH. "Our method has been approved for use in conventional arable farming, and is even recommended for use in organic farming. We are planning to set up a spin-off company to take over and expand these production activities," reports Röder. At the Parts2Clean fair from October 28 to 30 in Stuttgart, the research team will be demonstrating numerous other disinfecting and sterilization technologies for the pharmaceutical and medical engineering industries, in addition to the e-ventus technology for seeds described above (Hall 7, Stand H 802 / I 903).

Source: Fraunhofer-Gesellschaft