Meat Tenderness Affected By Chilling Method
September 1, 2012

Turns Out, Blast Chilling May Make Your Pork Chops Less Tender

April Flowers for - Your Universe Online

Meat scientists report that a method of chilling meat could affect the tenderness of pork. The results of this study were recently published in the Journal of Animal Science.


Apparently, yes. There's even an association, the American Meat Science Association. According to the organization, meat scientists "create and apply science to efficiently provide safe and high quality meat, poultry, fish/seafood, and meat from other managed species."

Led by Roman L. Hruska US Meat Animal Research Center (USMARC), the scientists conducted a study to compare pork longissimus muscle (LM) tenderness and other meat quality traits between different stunning methods and carcass chilling rates at slaughter facilities.

The USMARC facility is in Clay Center, Nebraska, and its mission is to improve meat quality, help keep livestock production both economically and environmentally sustainable, and help make meat safer and more affordable for consumers.

The USMARC research team acquired pigs from a single barn on a commercial finishing operation. The pigs were then taken to one of three slaughter facilities. Plant A used CO2 stunning and conventional spray chilling; Plant B used CO2 stunning and blast chilling; and Plant C used electrical stunning and blast chilling.

“Blast chilling is a rapid cooling of the muscles for at least 45 minutes at less than negative ten degrees Fahrenheit,” said Steven Shackelford of USMARC.

Blast-chilling systems are used to increase packing plant throughput, enhance food safety, and improve meat quality, particularly water-holding capacity of muscles from stress-susceptible pigs.

After the animals were slaughtered, the carcasses were cooled by either blast chilling or conventional spray chilling. The researchers then took a loin from the left flank of each animal for evaluation. The loins were sent to USMARC, where they were refrigerated and weighed for purge loss, or a loss of fluid from the meat.

The meat was cooked at 15 days post mortem so that the researchers could measure the LM slice shear force, which is a measurement of meat tenderness. The higher the shear force, the tougher the meat. The meat was tested for marbling, muscle fiber length, moisture content, color, the breakdown of proteins, and intramuscular fat content.

The research team found no advantages to loin quality from blast chilling. In fact, what they found was a 13-fold increase in excessively tough samples from blast chilling, indicating that chilling methods in pork packing plants can play a strong role in loin chop tenderness.

“This study showed that blast chilling can have a very substantial negative impact on tenderness. So there are trade-offs that must be considered,” said Shackelford.

The results of this study are surprising. Past literature suggests that blast chilling should have little impact on the quality of the meat. The research team believes this might be due to changes in genetics and production systems, which affect the chilling rate.

The team found that regardless of the chilling method used, CO2 stunning resulted in darker LM lean color and greater LM water-holding capacity than electrical stunning.

The USMARC team would like to see further studies to determine whether differences exist across conventional and blast-chill plants over multiple seasons and multiple production systems.

“Given the real and perceived advantages of blast chilling, we think that more research is needed to determine optimal blast-chilling conditions for a balance of all meat quality traits and other economical issues,” said Shackelford.