Managing Pork pH for Better Quality

A professor from Iowa State University (ISU), Ames, has been investigating the relationship between higher pH and pork quality, as well as ways to maintain a higher pH during processing and handling.

According to a recent ISU press release, Ken Prusa, professor of food science and human nutrition and animal science, has been researching ways to improve pork quality since he joined the school's faculty in 1985. In those days, the industry was primarily looking for ways to make pork leaner. These days, he and other food scientists generally think pork is lean enough, and are looking at ways to add value to "The Other White Meat."

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

His research revealed that the Japanese buyers were selecting pork cuts based on their pH, which is indicated by a darker color of the meat. Lower acid levels help prevent potential acidic damage to muscle proteins, which can cause the meat look pale and reduce its water-holding capacity.

"Through sensory testing, we found pH to be a pretty strong driver of ultimate pork quality," said Prusa. "Higher-pH products are more tender, juicy and flavorful. It tuned us into an opportunity to add value to pork products in the marketplace."

Several factors, including genetics, processing procedures, preslaughter animal stress and postslaughter treatment, can affect pork pH. "Chilling is a big factor in processing," said Prusa. "It's critical to lower the temperature of the carcass fairly rapidly. Otherwise, the pH may drop too low before chilling can stabilize it." Reducing stress just before slaughter by keeping the animals as calm as possible can also improve pork quality. "Stress causes a high metabolism rate, which creates a lot of adrenaline," he continues. "When that happens right before slaughter, it causes a really rapid pH decline. If there's a rapid pH decline in the hot carcass, it's even worse. At that point, there's not much you can do for quality."

Prusa is working with packers, processors and geneticists to take advantage of the effect of pH on pork quality. "There's probably a premium market in the United States for higher-pH pork," he said. "Some major retailers on the West and East Coasts are figuring out that the best pork is exported. We're looking at specific ways to provide them higher-pH products."

The ISU press release notes that some processors and packers are moving toward buying pigs on the basis of pH, and that meatpackers are beginning to routinely measure pH on production lines. "When that happens, it will be like when they started measuring leanness," said Prusa. "Pigs got lean. And when consumers started to pay for leanness, pigs got lean in a hurry.

"We hope that through our work with packers and processors, we'll see higher-pH products on the market soon," he continued. "We're looking at ways of marketing products on the basis of the deeper, richer color and flavor. People can see the difference. Once they taste it, the better quality is obvious. If you tell the story correctly, back it up with scientific information, and have a better product. Consumers will buy it."