Woody Breast
Researchers continue studying the woody breast condition as equipment manufacturers focus on detection.

Coming across broiler fillets with the woody, or wooden, breast condition is nothing new for poultry processors these days. The condition that causes hardened tissue in broiler breast meat can be found in any breed of chicken. In fact, researchers estimate the condition affects between 5 percent and 10 percent of the current broiler population. Unfortunately, researchers still don’t know what causes the condition and how it can be prevented.

The woody breast condition does not affect the animal’s welfare nor does it pose a food safety or health risk to consumers, but the tough, rubbery breast meat is unpalatable when consumed which means dollars lost to processors, retailers and restauranteurs.

John Glisson, Ph.D., vice president of research programs at the US Poultry & Egg Association (USPOULTRY) says, “Companies that are producing chicken breast fillets are producing them for a specific purpose, whether that’s for retail sale or for a specific foodservice customer. If they [processors] find woody breast they have to remove the product and use it for something else that’s not as profitable. That premium product is valuable. If you start throwing it away, that’s a lot of money to waste.”

Members of academia, geneticists, veterinarians and scientists, as well as researchers at processing and breeder operations, are all investigating the cause of this mysterious myopathy.

“The research on woody breast has just sort of evolved over time. A lot of research just evolves. You answer one question and then five others come up. Then you just go down another route to answer those questions,” says Casey Owens-Hanning, Ph.D., associate professor in the Poultry Science Dept. at the Univ. of Arkansas, Fayetteville. “I worked on white striping research for 10 years or so and when woody breast came up we realized they’re related, so some of my research evolved into that.”

However, when it comes to woody breast, Owens-Hanning says, “There’s still a lot of research to be done.”

New findings

New research could indicate that the condition has existed a lot longer than originally suspected. USPOULTRY and the USPOULTRY Foundation announced July 18 that a research project at North Carolina State Univ., Raleigh, concluded that the woody breast condition has existed in broiler chickens since the 1950s. Researchers also proposed a new name for this condition – Superficial Pectoral Myodegeneration and Sclerosis: Broiler Breast Myopathy (BBM).

The project, financed by a foundation gift from Rogers, Arkansas-based Ozark Mountain Poultry and led by John Barnes, Ph.D., took a closer look at the onset of woody breast lesions in three breeds of modern broilers as well as a line of broilers from the 1950s. While the lesions were discovered to be more severe in modern day broilers, the condition was evident in the 1950s line as well. In addition, evidence of the lesions in the breast muscles were present in all lines of the broilers at two weeks of age.

According to the research summary, while the condition begins to develop within the first two weeks of age in chickens, by three weeks, some birds have marked muscle degeneration and most develop muscle disease by four weeks.

“Scar tissue replaces damaged muscle, which contributes to muscle hardness (woody breast). Additional space from lost muscle can fill with fat, which helps explain the relationship between BBM and ‘white striping’,” according to the research summary. Muscle hardness plateaus at about two months and remains until about 13 weeks of age.

Researchers detected a correlation between the inflammation of small veins in the breast tissue and the severity of muscle damage. “The significance of this change is unknown, but it is reasonable to assume that blood flow to the muscles is affected. No cause for the vascular damage is known, but a virus has been isolated from affected muscles,” the summary states.

Looking closer at the role of the virus in BBM is the subject of a current research project by USPOULTRY.

Researchers from Drongen, Belgium-based Nuscience Group have developed a feed-based solution to reduce incidences of woody breast. According to Nuscience, researchers narrowed down the cause of the myopathy to the increasingly high growth rates of birds and high meat yields. According to the company: “Due to the fast muscle growth and the enlarged muscle cells, the space between muscle fibers is reduced. This restricts the blood supply to the muscles, which can no longer reach the desired oxygen levels. The resulting dead muscle cells harden the meat, causing the wooden breast.”

The company’s product, Q-prove, can lower the chances of woody breast by reducing oxidative stress and supplying more oxygen to the cells. “With Q-prove, the muscle cells are able to grow very fast without any meat loss,” according to the company.

According to field trial results in Europe and South America, Q-prove can reduce the incidence of severe woody breast from rates as high as 20 percent down to approximately 2.5 percent.

The company plans to ship the product from its Drongen-based manufacturing plant to high-volume markets, including the US, Brazil and Europe.

Woody Breast
The Tomra QV-P is an inline tool designed to help processors identify woody breast on processing lines.

Detection and inspection

The primary way woody breast is detected in processing plant environments is through inspection by quality assurance personnel on the processing line. Line workers use tactile evaluation by feeling the chicken breasts for the hardened tissue. Then they can segregate the affected product from the rest.

Last year, USPOULTRY helped fund a research project that investigated possible ways to use imaging technology to detect the woody breast condition. Results from the study, “Identification of the Wooden Breast Condition in Broiler Breast Fillets Using Imaging Technology,” were released Aug. 19, 2016.

In this study, which was funded in part by $11,500 from USPOULTRY and an endowment from St. Cloud, Minnesota-based GNP Co., researchers used various imaging technologies to attempt to differentiate between the muscle surface characteristics of normal fillets and those affected with woody breast. Study results concluded that imaging analysis could clearly distinguish between fat, muscle and connective tissue on the surface of breast fillets to assess their relative quantities. Breast fillets in the study could be categorized as having woody breast with more than 95 percent accuracy.

“These results point to the feasibility of adapting imaging technology to detect wooden breast in an online processing plant setting,” USPOULTRY said in a statement. “The development of such imaging technologies for detecting the WB condition would allow processors to more easily and accurately segregate product based on quality and uniformity.”

The next step, Glisson says, would be for an imaging company to design specific equipment that could go into a commercial setting to perform this task. Enter the QVision system from Asker, Norway-based Tomra.

The sorting equipment company’s QVision system has been used in the red meat and seafood industry for more than five years. Its patented “interactance spectroscopy” technology uses infrared light to penetrate about 1 in. into a piece of meat to analyze fat, moisture and protein.

After the woody breast condition became a more prevalent concern for poultry processors, Tomra decided to take a closer look at its QVision system to see if it could be tweaked and used to detect the condition. “With the muscle myopathy present in the upper 1 in. of the chicken breast, it allowed us to deploy our existing technology to look for the specific changes in the chemical composition of the affected part of the fillet,” says Thorsten Niermeyer, business unit manager for process analytics at Tomra Sorting Ltd. Finding those changes in the chemical composition means being able to detect woody breast, Niermeyer says.

After a small amount of redesign, the Tomra QV-P is now being sold specifically as an inline tool to help processors detect woody breast on their processing lines. The inline system enables poultry processors to identify quality deviations and has the capability to communicate in real time with sorting conveyors or robots to remove affected product from the production line.

“The system not only detects the presence of woody breast, it also records the data and statistics per flock, allowing processors to track suppliers,” Niermeyer explains. “It provides information about the variation of the myopathy in different flocks, allowing comparison and payment terms according to quality.”

While a consensus has yet to be reached among researchers and industry academics about the cause of the woody breast condition, all agree that it’s in the processor’s best interest to be able to remove the product from the line before it ends up in the consumer’s mouth. Whether this is done manually or with detection equipment, it’s essential for poultry product quality control.

“Detecting woody breast allows processors to sell prime quality product, rather than getting customer complaints,” Niermeyer says. “There is monetary value for a processor, as they can receive the highest price for a premium product. Devaluing an entire batch, due to presence of woody breast fillets, would have severe financial consequences.”