Pressure combined with heat reduces prion infectivity in processed meats

May 07, 2003

The combination of high temperature and very high pressure in the preparation of processed meats such as hot dogs and salami may effectively reduce the presence of infective prions while retaining the taste, texture, and look of these meats, according to a study in today's Proceedings of the National Academy of Sciences (PNAS) Early Edition. The study was led by Paul Brown, M.D., of the National Institute of Neurological Disorders and Stroke (NINDS), a component of the National Institutes of Health within the U.S. Department of Health and Human Services. Other collaborators on the study, which was conducted in Europe with partial funding provided by the Ministero della Salute, Italy, included Rich Meyer (Tacoma Farms, Washington State) and Franco Cardone and Maurizio Pocchiari (both with the Ministero della Salute).

Scientists believe that bovine spongiform encephalopathy, also known as "mad cow" disease, entered the human food chain through beef products containing abnormal, or folded, proteins called prions. The disease manifests itself in humans as variant Creutzfeldt-Jakob disease. Since 1995 more than 140 patients, mostly in the United Kingdom, have died as a probable result of eating contaminated meat products.

Scientists have been looking for strategies to inactivate any possible infectivity in meats, and although processes such as autoclaving and exposure to strong alkali or bleach are known to inactivate prions, they cannot be used successfully in food preparation.

Richard T. Johnson, M.D., former neurologist-in-chief at the Johns Hopkins University School of Medicine and a senior advisor to the National Institutes of Health on the transmissible spongiform encephalopathies, said "the idea of using high pressure to decrease prion activity is interesting and unique and may lead to additional studies." Extensive surveillance by the U.S. Department of Agriculture has not detected bovine spongiform encephalopathy in the United States. The transmission of prion diseases through the food chain is a concern among public health officials.

To conduct the study, the scientists prepared a paste of scrapie prion-infected brain tissue mixed with hot dogs. They then exposed the paste to temperatures of 120-135 degrees Celsius (250-275 degrees Fahrenheit) and short bursts of ultra high pressure, in excess of 100,000 lbs. per square inch. The scientists found that they were able to retain the basic texture and flavor of the processed meat while reducing the prions to non-infective levels. This may have application in improving the safety of meat products.

The combination of temperature and high pressure has been used commercially for the past 15 years to reduce the amount of bacteria in foodstuffs and to preserve ham, chicken, salsa, and other foods. Dr. Brown said his team "took the process one step further, to see if it would kill prions, which it did." He called the discovery a relatively inexpensive, practical step to potentially improve the safety of processed meats.

He added the approach may have implications for understanding the prion structure. "At a constant high temperature, we know that more and more prion inactivation occurs at higher and higher pressures. We hope that studying the structure of prions at increasing levels of pressure may allow us to better understand how the abnormal prion misshapes or unfolds," said Dr. Brown.
The NINDS is a component of the National Institutes of Health in Bethesda, Maryland, part of the U.S. Department of Health and Human Services, and is the nation's primary supporter of biomedical research on the brain and nervous system.

NIH/National Institute of Neurological Disorders and Stroke

Related Prions Articles from Brightsurf:

How understanding the dynamics of yeast prions can shed light on neurodegenerative diseases
How understanding the dynamics of yeast prions can shed light on neurodegenerative diseases

Household bleach inactivates chronic wasting disease prions
A 5-minute soak in a 40% solution of household bleach decontaminated stainless steel wires coated with chronic wasting disease (CWD) prions, according to a new study published in PLOS One.

Mad cow disease: A computational model reveals the mechanism of replication of prions
An article published in the journal PLOS Pathogens reports a realistic computational model for the structure and mechanism of replication of prions, infectious agents responsible for mad cow disease and other neurodegenerative disorders of human and animals.

Breakthrough in chronic wasting disease research reveals distinct deer, elk prion strains
Researchers have developed a new gene-targeted approach to study chronic wasting disease in mice, allowing opportunities for research that has not previously existed.

How prions invade the brain
The spread of prions to the brain does not occur by direct transmission across the blood-brain barrier, according to a study published Nov.

Eyes of CJD patients show evidence of prions
NIH scientists and colleagues have found evidence of the infectious agent of sporadic Creutzfeldt-Jakob disease (CJD) in the eyes of deceased CJD patients.

Creutzfeldt-Jakob disease spreads prions throughout the eyes, researchers find
Researchers recently studied the eyes of 11 people with sporadic Creutzfeldt-Jakob disease (sCJD), the most common and well-known prion disorder.

CWD prions discovered in Wisconsin soils for the first time
New research out of the University of Wisconsin-Madison has, for the first time, detected prions responsible for chronic wasting disease (CWD) in samples taken from sites where deer congregate.

Researchers find infectious prions in Creutzfeldt-Jakob disease patient skin
In a Science Translational Medicine study published today, Case Western Reserve University School of Medicine researchers found that CJD patients also harbor infectious prions in their skin, albeit at lower levels.

Getting under the skin of prion disorders
Infectious prion proteins -- the causative agents of the fatal neurodegenerative disorder Creutzfeldt-Jakob disease -- can be detected in the skin of afflicted individuals, researchers now report.

Read More: Prions News and Prions Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to