This study of four domestic abattoirs in South Australia with Quality Assurance programmes in place, established the size of bacterial populations that could be expected on pig carcasses on entry to abbattoir dressing floors at pre-evisceration, the extent of contamination occuring during carcass dressing, and the effect of chilling on these populations. Analysis was conducted for salmonellae, Escherichia coli, Total Viable Count, and pseudomonads. Exterior swabbing was compared to swabbing of corresponding interior sites which are sterile initially. The interior swabbing sites were found to be a more reliable measure of contamination during the dressing process than the swabbing of already contaminated exterior sites. During the identification of some of the points of carcass contamination, the effectiveness of end-of-work foam cleaning programmes used at abattoir dressing floors and their relationship to the potential for airboure contamination of carcassed was examined and found to be positive. / Operators' work tools and hands were identified as sources of interior carcass contamination combined with failure of operators to adhere to Standard Operating Procedures (SOPs) during carcass dressing, especially those related to hand and forearm washing at appropriate times. Foot-operated full-immersion hot water units for operators' knives and steels were designed and installed at two abattoirs to give operators access to physically and biologically clean work tools throughout carcass dressing. Use of this innovation represents a world first in reducing bacterial contamination of carcasses during dressing. Knives and steels remained immersed in the 82 C hot water when not in use, eliminating the need for waist held tools, and left operators' hands free for washing according to SOPs. A detailed study of the social structure of dressing floors was made to determine how best to bring about the attitudinal changes necessary to have operators use the full-immersion hot water units correctly and at the same time to adhere diligently to the use of SOPs, especially those related to hand and forearm washing after dirty cuts, when changing from exterior to interior trimming, and between carcasses. The relatively high populations of E. coli detected on carcasses swabbed in the study was of concern due to the reported detection of enterohaemorrhagic serotypes at Australian farms and abattoirs. / This knowledge led to investigation of the ability of Australia's most common of these serotypes, O111, to attach to food processing grade stainless steel. The pathogen was found to attach readily to stainless steel test sufaces. Subsequent formation of biofilms on abattoir equipment, including operators' work tools, could result in continuing contamination of meat being processed and increased bacterial resistance to heat and chemical treatments used in cleaning. This finding must be of concern to abattoir management and public health authorities, and suggests that the hygiene at abattoirs needs immediate upgrading including providing operators access to clean work tools during processing and ensuring that SOPs are followed diligently at all times. Establishment of an independent monitoring authority to achieve these outcoms using microbiological verification appears to be an obvious solution. / Thesis ([PhDBiomedicalScience])--University of South Australia, 2004.
| Identifer | oai:union.ndltd.org:ADTP/267570 |
| Creators | Skull, John C. |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | copyright under review |
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