Pork Makeover: New Push for Dark Meat
Credit: USDA/Keith Weller
Credit: USDA/Keith Weller

Pork is getting a makeover as producers look to make the meat a little darker, an indicator of higher quality.

In 1987, the pork industry launched a campaign that ingrained the "whiteness" of pork in the heads of consumers. This push sprang from the perception that chicken and turkey were leaner choices than beef, lamb and pork. Since then, researchers worked hard to bring pork up to par and make it the leanest meat it could be.

Now, Ken Prusa, a professor of food science and human nutrition from Iowa State University, is convinced that pork is finally lean enough and consumers need to look at other characteristics when picking the right cut for dinner.

Pork pH

"I was doing research in a meat-packing plant and noticed that the Japanese export buyers always chose the darker pork," Prusa said. "I wanted to find out why, so I evaluated some darker products."

Color, Prusa found through various industry-funded studies, is an indicator of pH in pork, a measure of acidity or alkalinity. A pH of 1 is considered very acidic and a pH of 10 is very alkaline.

Dark-colored pork has a higher pH and so is less acidic than lighter-colored cuts. Acid damages muscle proteins and causes meat to be watery and light in color.

"Through sensory testing, we found pH to be a pretty strong driver of ultimate pork quality," Prusa said. "Higher pH products are more tender, juicy and flavorful."

Pork loin, for example, has an average pH of 5.7, whereas the higher quality pork tenderloin averages around 6.1 to 6.2 in pH, Prusa told LiveScience.

Relax, Porky

Keeping the animals relaxed before slaughter is one way to drive up the pH. Stress causes elevated adrenaline levels in the body, which then drop the pH levels in the animal.

Another factor may be temperature.

"Chilling is a big factor in processing," Prusa said. "It's critical to lower the temperature of the carcass fairly rapidly. Otherwise, the pH may drop too low before chilling can stabilize it."

With such methods, producers may be able to adjust the pH by a tenth, which Prusa says is quite significant.

"People can see the difference," he said. "Once they taste it, the better quality is obvious."