Test will determine laying system
A scientist in New Zealand has developed a test that could help to prevent cage eggs being fraudulently sold as free range.
The research in New Zealand has led to the development of a new method to identify the difference between eggs from caged hens and those from free range hens and from organically raised birds.
The test makes use of a scientific technique called isotope analysis. It is believed to be the first time that it has been used to distinguish eggs from different farming systems. It follows previous work by the same scientist to distinguish between organic and conventionally grown vegetables.
"The research came about when I was investigating differences between organic and conventional produce - specifically vegetables, but also meat, fish and eggs," said Karyne Rogers, the scientist involved in the breakthrough. She works at GNS Science’s National Isotope Centre in Lower Hutt, New Zealand. "I noted that it was possible to see differences between organic and caged hen eggs and I wanted to see if it would be possible to discriminate between all laying regimes as a tool which could then be used for certifiers, distributers, exporters and the poultry industry."
Dr Rogers compared different brands of off-the-shelf eggs from caged, barn, free range and organic farming regimes. By using isotope analysis, she found that almost all of the eggs could be distinguished by relating the carbon and nitrogen found in the egg to the hen’s diet. Dr Rogers says this is possible because diet directly reflects the type of farming environment in which the hens have been raised.
"Free-range and organically farmed hens normally have access to a wider range of food sources than caged hens, such as insects, vegetation or organic feeds, and this changes the isotope fingerprint of their eggs," she said.
The research was performed on egg yolk, albumen and egg membrane to see which egg components gave the best information about the hen’s diet. Dr Rogers said the technique offered considerable promise for the egg industry as an effective verification tool to guard against mis-labelling.
Egg fraud has been a concern of the free range industry. BFREPA is keen to ensure that consumer confidence in free range is not hit by cases of fraudulent labelling, and chairman Tom Vesey said it was very encouraging that such work was being conducted.
"If it was possible to develop such a test then we would welcome it. It could be another weapon in the armoury against fraud, which we all want to prevent. We would be very happy if the test could be shown to work effectively."
Dr Rogers said, "The technique is a good way to scientifically prove that eggs are truly free-range or organic. The next step is to seek industry funding to work directly with egg producers to further refine the technique so it can be fully tested and applied in the industry." She said she had been in contact with the New Zealand Egg Producers Federation and the association had been very supportive so far. "This research is still ongoing and is currently moving from supermarket eggs to the farms themselves, relating the chickens’ environment directly with their diet and nutrient uptake in the egg.
"The producers will supply us with eggs of known origin and corresponding feed. We can then test our method limitations, as there were a few eggs that did not fall into the expected ranges. We wish to have the supporting research to support this test ready by early 2010, and hope to convince certifying agencies and larger distributors that this method is, indeed, a useful technique to ensure proof of origin, labelling and traceability of their products."
She said that work was under way to ensure that the test would be effective in other parts of the world as well as in New Zealand. "We are currently applying for several funding opportunities here in New Zealand. We are also working in collaboration with a larger food research company in Europe to examine other chemical aspects of the eggs to ensure that we develop the most robust method for both northern and southern hemisphere eggs."
Combating egg fraud is the responsibility of the Egg Marketing Inspectorate, which is now part of Animal Health. A spokesman for Animal Health said he was aware that the use of stable isotopes as "a differentiation tool" was currently under development. Animal Health would continue to monitor progress of this work, he said.
The spokesman said that inspectors currently used an alternative method for differentiating between eggs from different production methods. "Animal Health Egg Marketing Inspectors are trained to use an ultra violet (UV) light test technique, which shows production marks such as cage lines and nest box floor marks (astro turf/rubber matting etc) which demonstrate the production method. Once the production method is established, it is compared with the stated production method of the batch of eggs being checked. No eggs are destroyed in the process and Animal Health has confidence in this method.
"Where production marks do not match stated production methods, inspectors will commence appropriate enforcement action," said the spokesman.
Dr Rogers’ findings have been published in an international scientific publication, the Journal of Agricultural and Food Chemistry. She has also presented her findings to the New Zealand Institute of Food Science and Technology annual conference in Christchurch.
