Food scientist Gene Lyon
begins to remove the large
breast muscles from an
chicken carcass. The meat
will be tested for tenderness
and other textural characteristics.
To a chicken lover, there are few things better than a
tender, juicy chicken breast as part of a satisfying meal. More than
likely, the succulent morsels came from a young, broiler-type bird,
one specifically raised to cook whole or in pieces. But a new processing
step developed by Agricultural Research
Service scientists may allow older, layer birds, those that produce
eggs for table use, to be processed at a later time just like broiler
birds. Usually these mature birds are processed for lower value items
such as feed, pressed products like chicken nuggets, or canned products
such as soup.
ARS researchers J. Andra Dickens, Clyde E. Lyon, Richard
J. Buhr, of the Poultry Processing and Meat Quality Research Unit, and
Brenda G. Lyon, of the Quality Assessment Research Unit, found that
electrical stimulation of the carcasses makes breast meat of mature
layer hens more tender, speeds up the processing time, and allows processors
to save space.
In 2000, poultry plants processed more than 8.25 billion
broilers, valued at more than $14 billion. In December 2001, the U.S.
inventory of laying hens was estimated to be 335 million birds, most
of which could be processed as high-quality meat by using electrical
"Electrical stimulation will allow more breast meat
from older birds to be sold at retail prices, as boneless breast fillets,
for example," says Dickens.
Processing broilers is an assembly-line affair with time
built in for chilling the meat before removing the bone. Breast muscle
that remains on the bony frame for 4 to 6 hours after the bird has been
processed is deemed to have optimal tenderness.
Reducing on-the-bone chilling time interferes with the
process of rigor mortis, making cooked meat tough and chewy. But, says
Dickens, "After chilling for 2 hours, the electrically stimulated
carcass is ready to be deboned, allowing workers to do this step during
the same shift instead of waiting for the next shift. It saves the processor
a lot of time."
The reason processors store carcasses in refrigerated
compartments is to allow the natural contraction of the muscle (rigor
mortis) to subside. This typically takes 8 to 24 hours. As unused energy
in the form of glycogen dissipates, the muscle relaxes and the bird
can be removed from refrigerated storage. ARS researchers have found
that applying pulsed electrical current forces muscles to use stored
glycogen more rapidly.
"Using electrical stimulation eliminates the need
to store carcasses in refrigerators for the standard 8 to 24 hours,
which can save processors millions of dollars annually," says Dickens.
And lower costs for industry usually translate into savings
for consumers.By Sharon
Durham, Agricultural Research Service Information Staff.
This research is part of Food Safety, an ARS National
Program (#108) described on the World Wide Web at http://www.nps.ars.usda.gov.
James Andra Dickens is with the USDA-ARS Poultry Processing
and Meat Quality Research Unit, Richard B. Russell Research Center,
950 College Station Rd., Athens, GA 30605; phone (706) 546-3205, fax
"A Tough Old Bird? No More!" was published in the
issue of Agricultural Research magazine.