Calcium sulphate used to fight listeria

An acidified calcium sulphate solution called Safe2O has been shown to significantly reduce the amount of Listeria monocytogenes on hot dogs and prevented regrowth of the pathogen over a 12-week period, according to a Texas A&M study funded by AMI Foundation.

"Safe2O offers the opportunity to decontaminate products that might become contaminated and offer a measure of safety after they have been packaged for some period of time,"​ said study author Jimmy Keeton of Texas A&M University​.

The solution, applied to the surface of hot dogs, could significantly reduce Listeria monocytogenes growth during the optimal 12-week shelf life the product typically has in a grocery or retail store.

The study found that Listeria monocytogenes numbers were reduced by 5.8 logs on the surface of hot dogs treated with Safe2O and remained at the minimum level of detection of 1.7 logs over a 12-week storage period at 40 degrees F (4.4 degrees C).

In the study, researchers divided each batch of frankfurters into inoculated (four strain Listeria monocytogenes cocktail) and non-inoculated groups. Researchers applied a Listeria monocytogenes mixture to the surface of 21 franks per treatment to give a final concentration of about 108 CFU/ml, or about 10 million microorganisms per gram.

Keeton said a ready-to-eat processing facility would not expect to find such high levels of Listeria monocytogenes on the product, but "if you're going to get protection, you should get it at this point."​

Of the two other substances that were tested, only the 3.4 per cent solution of lactic acid showed some reduction in Listeria monocytogenes growth on frankfurters. Treatment with lactic acid initially reduced the number of organisms, but failed to kill all of them and to prevent Listeria monocytogenes from growing again on the frankfurter during refrigerated storage. Potassium lactate applied to the surface did not effectively retard growth.

An hour after being treated with the Listeria monocytogenes mixtures, the frankfurters were submerged for 30 seconds in dips containing saline solution (control); acidified calcium sulphate (Safe2O); 3.3 per cent potassium lactate; or 3.4 per cent lactic acid. The frankfurters were then vacuum packaged, stored under refrigeration (4.4 degrees C) and evaluated at two-week intervals over a 12-week period.

The study's findings will give meat processors another tool in their food safety toolbox, said AMI Foundation President James H. Hodges.

The AMI Foundation​ is a non-profit organization dedicated to research, education and information projects that benefit the meat and poultry industry.