A New Zealand researcher has developed a free-range eggs test. Is that egg you’re about to eat free range, organic or from a caged bird? Now you will now egg-zactly where it came from thanks to this clever Kiwi chick.

A researcher has developed a technique to identify the difference between eggs from caged hens and those from free-range and organically raised hens.

It is believed to be the first time that eggs from different farming systems have been distinguished by using isotope analysis.

While it is not something the supermarket shopper could use every day, it has potential within the egg industry to avoid mislabelling.

Dr Karyne Rogers, of Geological and Nuclear Science’s National Isotope Centre in Lower Hutt, compared different brands of off-the-shelf eggs from cage, barn, free range and organic farming regimes. Using isotope analysis, she found almost all the eggs could be differentiated by relating the carbon and nitrogen found in the egg to the hen’s diet.

This was possible as diet directly reflected the type of farming environment where the hens were raised, Dr Rogers said.

“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 findings, recently published in the Journal of Agricultural and Food Chemistry, showed isotope analysis was a potentially useful technique for identifying eggs from different farming regimes.

ps. Here in the Fresh Kitchen, we love Glenpark Woodland free range eggs from the South Island. The hens have a little farm and forest area to scratch around in! The Glenpark eggs are sold NZ-wide in all good supermarkets.

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