June 15, 2009- A New Zealand researcher has developed a scientific technique using isotopes to
identify the difference between eggs from caged hens and those from
free-range and organically raised hens.
A New Zealand researcher has developed a scientific technique using isotopes 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.
Karyne
Rogers, of GNS Science’s National Isotope Centre in Lower Hutt,
compared different brands of off-the-shelf eggs from caged, barn,
free-range and organic farming regimes.
Using
isotope analysis, Dr Rogers found almost all the eggs could be
differentiated by relating the carbon and nitrogen found in the egg to
the hen’s diet. This is possible as diet directly reflects the type of
farming environment where the hens were 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,” Dr
Rogers said.
The findings, recently published in an
international publication, the Journal of Agricultural and Food
Chemistry, show that isotope analysis is a potentially useful technique
for identifying eggs from different farming regimes.
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 held considerable promise for the egg
industry as an effective verification tool to guard against
mis-labelling.
“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.
“New Zealand exports more
than two million free-range eggs a year and this test could provide
added consumer confidence, which would give New Zealand an advantage in
export markets.”
Previous work conducted by Dr
Rogers has shown it is also possible to differentiate between organic
and conventionally grown vegetables using isotope analysis. Dr Rogers
will present findings from this research next week at the New Zealand
Institute of Food Science and Technology annual conference in
Christchurch.
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