The rapid-cooling process, developed by Kevin Keener, a professor of food science, uses liquid carbon dioxide to stabilize the proteins in egg whites so much that they could be rated AA ¨l the highest grade for eggs ¨l for 12 weeks. Earlier research showed that the same cooling technology could significantly reduce occurrences of salmonella illnesses.
Eggs cooled under current methods lose the AA grade in about six weeks, Keener said.
"There is no statistical difference in quality between eggs as measured by Haugh units just after laying and rapidly cooled eggs at 12 weeks," he said. "This rapid-cooling process can provide a significant extension in the shelf life of eggs compared to traditional processing."
Haugh units measure an egg white's protein quality.
Keener's results, published in the journal Poultry Science, also show that membranes surrounding the eggs' yolks were maintained for 12 weeks when eggs were rapidly cooled. That membrane is a barrier that keeps harmful bacteria from reaching the yolk, a nutrient-rich reservoir that bacteria could use as a food source.
"The structural integrity of the yolk membrane stays strong longer, which may provide a food safety benefit," he said. "The membrane being stronger would be another defense against bacterial invasion, such as salmonella."
The rapid-cooling technology takes liquid carbon dioxide and turns it into a "snow" to rapidly lower the eggs' temperature. Eggs are placed in a cooling chamber and carbon dioxide gas at about minus 110 degrees Fahrenheit is generated. The cold gas is circulated around the eggs and forms a thin layer of ice inside the eggshell. After treatment, the ice layer melts and quickly lowers an egg's internal temperature to below 45 degrees, the temperature at which salmonella can no longer grow.
Keener's previous research showed that the carbon dioxide in bicarbonate form significantly increases the activity of lysozyme, an enzyme in the egg white that has bactericidal properties.
Traditionally, eggs are at more than 100 degrees when placed into a carton. Thirty dozen eggs are then packed in a case, and 30 cases are stacked onto pallets and placed in refrigerated coolers. The eggs in the middle of the pallet can take up to 142 hours - nearly six days - to cool to 45 degrees, Keener said.
Keener said a 2005 U.S. government report showed that if eggs were cooled and stored at 45 degrees within 12 hours of laying, there would be about 100,000 fewer salmonella illnesses from eggs in the nation each year.
Rapid cooling could also increase the ability to export eggs to places where this isn't possible today.
"You could send eggs anywhere in the world if you could get even eight weeks of shelf life at AA quality. We're seeing 12 weeks," Keener said. "Right now, you can't ship eggs anywhere in the world and expect to retain that quality."
Keener said with additional funding he would continue to study the benefits of rapid cooling, including inoculating the inside of shell eggs with Salmonella and examining how other proteins in the whites and yolks of eggs are affected.
Keener is a technical consultant to the American Egg Board and a member of the United Egg Producers Scientific Advisory Panel. His work was funded by Purdue and gift funds.
Kevin Keener developed a rapid egg cooling system that uses circulated carbon dioxide to create a thin layer of ice inside an egg's shell that cools the inside of an egg within minutes, strengthening proteins and increasing shelf life. (Purdue Agricultural Communication file photo/Keith Robinson)
A publication-quality file photo is available at http://news.uns.purdue.edu/images/2010/keener-eggs.jpg
Kevin Keener discusses the rapid egg cooling system.
Abstract on the research in this release is available at: http://www.purdue.edu/newsroom/research/2012/120611KeenerCooled.html
Brian Wallheimer | EurekAlert!
Climate change, population growth may lead to open ocean aquaculture
05.10.2017 | Oregon State University
New machine evaluates soybean at harvest for quality
04.10.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences
Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
23.10.2017 | Event News
17.10.2017 | Event News
10.10.2017 | Event News
24.10.2017 | Physics and Astronomy
24.10.2017 | Physics and Astronomy
24.10.2017 | Life Sciences