Increasing pressure is on meat processors to investigate antimicrobial decontamination treatments for carcases, in order to comply with United States requirements for minimising the risk of E.coli O157:H7 being present on carcases.
A number of potential treatments are available overseas, and are emerging in Australia.
Midfield Meats and CRF Colac have been investigating the potential for using chlorine dioxide, marketed in Australia under the brand name Twin Oxide®. This report details an in-plant validation study using bobby calf carcases inoculated with a mixed culture of E.coli organisms, non-toxis surrogates for E.coli O157.
The inoculum was applied to the carcase surface to acheive a level of at least 6 log10 E.coli cfu/cm2. Excision samples were taken from the rump, flank and brisket of each carcase prior to spraying with a 50ppm solution of chlorine dioxide; immediately after spraying; and following overnight chilling. After chilling, samples were also taken for analysis of potential chlorine residues on the carcases.
Prior to spraying, a mean E.coli count of 6.71 (range 5.74-7.27) log10 cfu/cm2 was acheived. Immediately after spraying, there seemed to be a slight, but not statistically significant, reduction in counts (mean 6.52, range 5.18-7.51 log10 cfu/cm2), while chilling did not cause further reductions (mean 6.57, range 5.60-7.46 log10 cfu/cm2).
No chlorine residues were detected, and there were no observed effects on carcase colour or odour.
However, as a result of the limited antimicrobial efficacy demonstrated, the outcomes of this study do not support the use of 50ppm chlorine dioxide as an effective intervention procedure.