Science - March 24, 2011

Rikilt can spot the real organic egg

Rikilt has developed a successful test for distinguishing organic eggs from the rest. This should make it much more difficult for egg producers to cheat.

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Every week millions of eggs are delivered to the supermarkets by poultry producers: standard eggs from the batteries, free-range eggs, barn eggs from chickens with access to the outdoors, and organic eggs. You cannot tell the difference from the egg, so the consumer just has to trust that the eggs end up in the right box. But fraud with eggs can be a very lucrative business. If you sell a standard egg as an organic one, you can make 7 cents per egg. So there is a need for a method of verifying organic eggs.

Yolk pigments

Rikilt tested three methods. The first method is to measure the carotenoid levels in the egg. 'Carotenoids are the yellow pigments in the egg. Some of them are higher in organic eggs and others in standard eggs', explains researcher Saskia van Ruth. You cannot see the different with the naked eye but under Rikilt's apparatus it is quite clear. The second method Van Ruth applied was to measure the difference in the fatty acids in organic and standard eggs. The fatty acid composition of organic and standard livestock feeds differs, and the differences are visible in the egg.
The third method is also based on the method of cultivating the chicken feed. Standard livestock feed is grown using artificial fertilizer and organic feed is grown without it. This creates a different nitrogen isotope balance in the feed and, via the hen, in the egg. Measuring the nitrogen isotopes in the egg brings that to light.

Interest abroad
The institute analysed hundreds of eggs from both standard and organic poultry farms in 2009 and 2010, and can verify almost all organic eggs. It even seems possible to spot the difference between fully free-range eggs and those with some access to the outdoors. If there is any doubt, a combination of the three methods can provide certainty, says Van Ruth.
The new method has attracted considerable interest. Rikilt conducts surveys for Skal, the inspector for organic produce in the Netherlands. Other European countries have shown an interest, as have Canada and Israel. 'We are going to expand the research to include eggs from other countries and share the methods in the EU Network of Excellence MoniQA.'

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