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2005 Swine Research Review - Pork Quality

Pork Quality

Improved Carcass Chilling Enhances Pork Quality

Subtle differences in the harvest process have the potential to improve fresh pork color and water-holding capacity.

In a study at the Iowa State Meats Laboratory, reducing scalding time from 7.6 to 5.6 minutes expedited the start of carcass chilling, and produced a slightly lower loin temperature two hours postmortem and a higher loin pH.

The end result was an improvement in pork color and water-holding capacity.

Loins from 64 pork carcasses were selected for quality evaluation immediately after fabrication one day postmortem. Fresh pork color, firmness, drip loss, pH and temperature were measured. Samples from 40 pork loins were evaluated five days postmortem for purge loss, color, pH and texture.

The more rapid scald treatment reduced the time on the processing floor by about 5 minutes. The 5.6-minute scald treatment also consistently produced lower Minolta L values (indicating darker pork) and pork loin chops with lower hue angle values (indicating less discoloration).

Those observations were confirmed by results from the quality evaluation five days postmortem.

Drip loss was also significantly lower in loins from carcasses in the 5.6-minute scald group. Shorter scalding produced a higher pH after the initial chilling period of two hours postmortem.

However, scald duration did not affect purge loss in vacuum bags during a five-day storage period.

Results show that small but significant improvements in the consistency of fresh pork can be achieved by altering slaughter processes.

Researchers: G. Mendez, E. Huff-Lonergan and S.M. Lonergan, Iowa State University. Contact S.M. Lonergan by phone (515) 294-9126, fax (515) 294-5066 or e-mail

Risk of Toxoplasma Infection Evaluated in Retail Meat Products

Representative blood samples from the National Health and Nutrition Examination Survey indicate that 22.5% of the U.S. population ages 12 and over are infected with Toxoplasma gondii (T. gondii).

This single-cell parasite causes mental retardation, loss of vision and other congenital health problems in humans. It is also an important cause of death and illness in immunosuppressed individuals.

In addition to congenital transmission, there are two other modes of transmission of T. gondii. People become infected by eating food or drinking water contaminated with oocysts excreted by infected cats, or by eating uncooked meat containing tissue cysts of T. gondii.

Scientists at the Beltsville Agri­cultural Research Center (BARC) in Beltsville, MD, and the Centers for Disease Control (CDC) in Atlanta, GA, conducted a survey of the prevalence of T. gondii in 6,282 samples of pork, beef and chicken (2,094 samples each) in 698 retail stores from 28 regions across the United States. Each sample purchased from the meat case was at least 2.2 lb.

Pork was the only meat found to contain viable T. gondii tissue cysts; viable Toxoplasma parasites were detected in eight samples.

Overall, the prevalence of viable T. gondii in retail meat was low. The BARC/CDC survey suggested that the actual risk of someone buying meat contaminated with T. gondii was 38% per decade. Over a 10-year period, if 100 people across the nation purchased pork from the retail meat case, 38 of them would have purchased meat containing T. gondii tissue cysts. In the northeastern United States, where the prevalence in pork is higher, 78 of the 100 would have purchased infected pork.

The researchers concluded that the risk of acquiring contaminated meat, as determined by their meat-case survey, is far too low to explain the source of most of the T. gondii infections in the United States.

They noted other factors must be responsible for human infection, including other types and cuts of meat, exposure to soil contaminated with cat feces and unfiltered water.

Researchers warned consumers, especially pregnant women, to be aware they still could acquire T. gondii from ingestion of undercooked meat, particularly pork.

Cooking meat to an internal temperature of 151° F. kills T. gondii. Post-harvest processing techniques, such as hard chilling and pumping, also kill T. gondii tissue cysts.

Researcher: Dolores Hill, U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center. Contact Hill by phone (301) 504-8770 or (301) 504-8300, fax (301) 504-6273, or e-mail