Ozone and Disinfection of Pork Carcasses
Carcass halves that were directly treated with aqueous ozone at a concentration of just over 2 ppm had an average of 67.6% decrease in microbial loads when compared to their untreated counterparts. The microbial loads of all carcass halves were relatively low when compared to carcasses not involved in this test and not proximal to the test carcasses. One explanation is that carcasses not directly sprayed with aqueous ozone were still subjected to misting (over spray) due to the nature of the spray wand tip and strong air currents in the area. All carcass halves were spaced apart from each other as far as possible (approximately 5 to 6 feet) but after continuous spraying in the area some misting began to circulate in the currents. Also, ambient ozone (gaseous, at 0.3 ppm) in the area after spraying could have been a factor affecting the microbial loads on all carcass halves.
The only discernible organoleptic difference between treated and untreated halves was that the fat on the treated halves had a slightly lighter tint to it than that of the untreated halves. Both the Quality Assurance Department and Production Manager commented that the difference was not undesirable. The muscle tissues had no discernible differences at this concentration of aqueous ozone. It is hypothesized that the darkening of the fat color may increase with increased concentrations of aqueous ozone. It is not known if porcine muscle color would also darken with increased concentrations. For bovine muscle, this is in fact the case as other studies have shown.
Relative to employee safety, there was an ambient ozone concentration in the area of 0.3 ppm after 45 minutes of continuous flow from the spray wand. OSHA states that an employee may be subjected to 0.8 ppm ambient ozone for an 8-hour period. At higher ambient concentrations the allowed exposure time decreases. No odor of ozone was detected during the test. Although some of the literature states that ambient ozone can be smelled at a concentration of 0.2 ppm I did not detect any odor. I was wearing a mask that covers nose and mouth, which may have decreased my ability to smell.