Egg yolk pigments betray egg's origins.
But it is about to become a lot more difficult to pull the wool over consumers' eyes in this particular way. Rikilt has developed a test for telling organic eggs apart from conventional eggs by the yellow pigments in the yolks. On analysing eggs from nine European countries, Rikilt's test correctly identified an organic egg 39 times out of 40. That one exception, an egg from an Italian farm, was probably a case of fraud.
The test can be further adjusted for each country, says Rikilt researcher Saskia van Ruth. 'If other countries want to introduce our method, we can adapt the test for them, because Italian organic eggs could have a slightly different range of pigments that Dutch ones.' Rikilt's method is already in use in the Netherlands at Skal, the monitoring institute for organic produce, as well as at NGOs such as animal welfare organization Wakker Dier.