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Researchers differ on impact of aging, genetics on beef tenderness
By SARAH B. AUBREY
Indiana Correspondent

CLAY CENTER, Neb. — What makes beef tender? Do good genetics guarantee good eating quality? Many meat science experts and food lovers say that aging improves tenderness, but how many days of aging are adequate?

With new research from the Meat Animal Research Center (MARC) in Clay City, Neb. and the University of Minnesota, the story of beef eating quality continues.

“The heritability of tenderness in beef is approximately 45 percent, which means that 45 percent of the observed variation in tenderness of cooked beef is due to the genetics (or parents) of the animal,” said Richard J. Epley, in a piece published by the University of Minnesota.

Epley indicated that there are as many as 12 different factors, including heritability, which affect how tender beef is when eaten. Among these are: breed, age, feeding practices, aging, quality grade, muscle-to-muscle comparisons, suspension and chilling of the carcass, and use of electrical stimulation or mechanical or chemical tenderizing on the carcass.

Researchers at MARC have focused on the practice of aging at slaughter.

According to a research article found in the October 2005 The Register, “MARC has found meat is tender right after slaughter, and then toughens before starting to become tender again. The scientists recommend that steaks should not be sold until they have been aged for 14 days.”

The length of time for aging is debatable between researchers, however.

“The increase in beef tenderness (due to aging) continues only for approximately 7-10 days after slaughter when the beef is held at approximately 35 degrees F.,” said Epley.

In addition to conflicting views on the use of aging in beef, major packers rarely age for more than a couple of days, regardless of recommendations from academia.

At MARC a group of researchers published a study in the March 2006 Journal of Animal Science that may help clarify the beef tenderness issue.

This research team discovered the use of gene markers for enzyme Calpastatin and U-Calpain, a protein variation, can be used to determine beef tenderness.

The study’s interpretive summary indicated, “The markers were tested on two diverse populations of cattle (Bos indicus and Bos Taurus) and crosses between those populations. Regardless of the population, the marker’s effects on tenderness were nearly independent and therefore can be used to genetically improve tenderness.”

The study measured tenderness and palatability traits based upon tenderness score, juiciness and flavor intensity.

According to MARC’s journal report, “Markers developed at the calpastatin and U-Calpain genes are suitable to be used in conjunction to identify animals with the genetic potential to produce meat that is more tender.”

For more information on Epley’s article on aging beef, visit www.extension.umn.edu/distribution/nutrition/DJ5968.html

For more information on the MARC study, visit the Journal of Animal Science website, http://jas.fass.org/

This farm news was published in the June 7, 2006 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee.

6/7/2006