Meta-analysis on the effect of interventions used in cattle processing plants to reduce Escherichia coli contamination

Driving forces shaping the microbial ecology in meat packing plants

Meat production is a complex system, continually receiving animals, water, air, and workers, all of which serve as carriers of bacteria. Selective pressures involved in different meat processing stages such as antimicrobial interventions and low temperatures, may promote the accumulation of certain residential microbiota in meat cutting facilities. Bacteria including human pathogens from all these sources can contaminate meat surfaces. While significant advancements have been made in enhancing hygienic standards and pathogen control measures in meat plants, resulting in a notable reduction in STEC recalls and clinical cases, STEC still stands as a predominant contributor to foodborne illnesses associated with beef and occasionally with pork. The second-and third-generation sequencing technology has become popular in microbiota related studies and provided a better image of the microbial community in the meat processing environments. In this article, we reviewed the potential factors influencing the microbial ecology in commercial meat processing facilities and conducted a meta-analysis on the microbiota data published in the last 10 years. In addition, the mechanisms by which bacteria persist in meat production environments have been discussed with a focus on the significant human pathogen E. coli O157:H7 and generic E. coli, an indicator often used for the hygienic condition in food production.

Performance Metrics for Slaughter and Dressing Hygiene at Australian Beef Export Establishments

ABSTRACT

A study was undertaken to examine hygienic control of the slaughter and dressing process for beef cattle at Australian export processing establishments. Samples were collected from two points during the process: immediately after hide removal and at the completion of dressing before the commencement of chilling. Hindquarter and forequarter samples were collected from 24 establishments, half of which (n = 12) used some form of microbial intervention (in addition to trimming). The overall contamination level on carcass sides was low and was reduced between hide removal and entering the chiller. The concentration and prevalence of indicator bacteria were higher on samples from hindquarters than on samples from forequarters. Application of an intervention, such as hot water, in addition to trimming resulted in a greater reduction in the concentration and prevalence of indicator bacteria than trimming alone, although the level of Escherichia coli and coliform bacteria on all samples was too low to allow meaningful comparisons to be made. Salmonellae were isolated from 2.09 and 0.56% of samples after hide removal and before chilling, respectively. Application of an intervention in addition to trimming did not result in a significant reduction (P = 0.4) of Salmonella prevalence on prechill carcasses. Low levels of bacteria were found on carcasses after hide removal. This, combined with small reductions as a result of trimming and sometimes other interventions, resulted in carcasses with very low levels of bacterial contamination. If performance metrics were to be applied to the slaughter and dressing process, a measure of the expected contamination at the end of the process would provide a more unequivocal measure of the process than either contamination on the carcass after hide removal or any reduction achieved as a result of the dressing process.

HIGHLIGHTS

Sustainability of safe foods: Joint environmental, economic and microbial load reduction assessment of antimicrobial systems in U.S. beef processing

Various antimicrobial interventions are applied sequentially in the beef processing industry to reduce microbial load on beef products by using intensive inputs (e.g., chemicals, energy), high strength wastewater, and potentially result in meat discoloration. This study serves as the first analysis to jointly evaluate environmental and economic assessment with its microbial load reduction of proposed antimicrobial systems in the U.S. beef processing industry to identify relatively sustainable systems that minimize environmental and economic impacts while providing microbial safe meat. Specifically, forty potential sequential antimicrobial systems were proposed and evaluated from three perspectives: microbial load reduction, environmental, and economic impacts, by meta-analysis, life cycle assessment, and operational cost analysis orderly. The results show that the antimicrobial systems applying steam pasteurization during the main intervention offer high microbial load reduction (>4.2 log CFU/cm² reduction from a hypothetical initial contamination at 5.0 log CFU/cm²). Human health impact (31.0 to 65.6%) and ecosystem toxicity (3.6 to 12.5%), eutrophication (11.9 to 15.5%) and global warming (6.4 to 22.2%) are the main contributors to the overall environmental single score among the forty antimicrobial systems. Antimicrobial chemicals (up to 82.8%), wastewater treatment (up to 12.7%), and natural gas (up to 10.7%) are the three major drivers of operational cost for sanitizing 1000 kg hot standard carcass weight (HSCW). Devalued (discolored) meat due to contact with heat from steam pasteurization or hot water wash has a considerable increase in economic ($4.5/1000 HSCW) and environmental (especially at farm stage) impacts. Certain antimicrobial systems (e.g., water wash followed by steam pasteurization) were found to be more promising with satisfactory effectiveness, better environmental and cost performance under uncertainty (1000 Monte Carlo simulations). Results from this study can guide the U.S. beef processing industry to advance sustainability while protecting human health from foodborne illness.