Microbial assessment of an upward and downward dehiding technique in a commercial beef processing plant

Transition of microbial contamination on the surface of carcass during the cattle slaughter process

In this study, we aimed to investigate how microbial contamination progresses on the carcass surface during the slaughter process. Cattle carcasses were tracked during a series of slaughter processes (five steps), and carcass surfaces (four parts) and equipment (nine types) were swabbed to investigate the bacterial contamination. Results showed that the outer surface (near the rear region of the flank [Top round] and [Top sirloin butt]) had significantly higher total viable counts (TVCs) than inner surface (p < 0.01) and that TVCs gradually decreased along the process. Enterobacteriaceae (EB) counts were high on the splitting saw and in top round region, and EB was detected on the inner surface of the carcasses. Furthermore, in some carcasses, Yersinia spp., Serratia spp., and Clostridium spp. present on top round and top sirloin butt immediately after skinning and remained on the carcass surface after the final process. These bacterial groups are detrimental to beef quality as they can grow in the package during cold distribution. Our results show that the skinning process is the most prone to microbial contamination, including psychrotolerant microorganisms. Moreover, this study provides information for understanding the dynamics of microbial contamination in the cattle slaughter process.

Food safety incidents in the red meat industry: A review of foodborne disease outbreaks linked to the consumption of red meat and its products, 1991 to 2021

Red meat is a significant source of human nutrition, and the red meat industry contributes to the economy of nations. Nonetheless, there is a widespread global concern about public health issues posed by severe food safety incidents within the red meat industry. Most of these incidents are associated with foodborne disease outbreaks that impact individual consumers, food businesses and society. This study adopts a systematic search and review approach to identify three decades of published investigation reports of global foodborne disease outbreaks linked with the consumption of red meat and products made from them. The review aims to evaluate the critical features of these outbreak incidents to get insight into their contributing factors and root causes. In particular, this review discusses the transmission setting (origin of pathogenic agents), the food vehicles mostly incriminated, the causative pathogens (bacteria, viruses, and parasites) causing the most illnesses, and the most commonly reported contributing factors to the outbreaks. This information can help researchers and food business operators (FBOs) inform future risk assessment studies and support risk management activities in developing risk-mitigating strategies for the industry. Findings from this study suggest that implementing food safety management strategies which include adequate control measures at all stages of the food chain, from farm to fork, is imperative in preventing outbreak incidents. Of equal importance is the need for enhanced and sustained public education about the risk of foodborne illnesses associated with meat and its products whilst discouraging the consumption of raw meat products, especially by high-risk groups.

Beef abattoir interventions in a risk-based meat safety assurance system

In risk-based meat safety assurance system, the use of interventions is intended to accomplish the meat safety targets on chilled carcasses, particularly in situations when an abattoir is unable to sufficiently reduce risks arising from specific farms/animal batches by using process hygiene alone. Furthermore, interventions are considered whenever food safety authorities identify meat production processes associated with high risks for consumers. This paper overviews the role of beef interventions in a risk-based, meat safety assurance system. Cattle hide interventions (chemical hide washes and microbial immobilisation treatment with shellac) and beef carcass interventions (pasteurisation treatments with hot water and/or steam and organic (lactic) acid washes), show consistent reduction effects of aerobic bacteria and faecal indicators and reduced prevalences of naturally present VTEC and Salmonella. The review also identified interventions where there was a lack of data and further research was needed, and other contextual factors to inform the risk management decisions for further development of risk-based meat safety assurance system.

Analysis of Bacterial Diversity in Relation to the Presence of the Top 7 Shiga Toxin-Producing Escherichia coli throughout Australian Beef Abattoirs

ABSTRACT

There is increasing evidence that diversity changes in bacterial communities of beef cattle correlate to the presence of Shiga toxin-producing Escherichia coli (STEC). However, studies that found an association between STEC and bacterial diversity have been focused on preslaughter stages in the beef supply chain. This study was designed to test a hypothesis that there are no differences in bacterial diversity between samples with and those without the presence of the top 7 STEC (O26, O45, O103, O111, O121, O145, and O157) throughout processing in an integrated (abattoir A) and a fragmented (abattoir B) Australian beef abattoir. Slaughter and boning room surface samples from each abattoir were analyzed using 16S rRNA amplicon sequencing and tested for the top 7 STEC following the Food Safety and Inspection Service protocol. Potential positives through slaughter were similar between the abattoirs (64 to 81%). However, abattoir B had substantially reduced potential positives in the boning room compared with abattoir A (abattoir A: 23 and 48%; abattoir B: 2 and 7%). Alpha diversity between the sample groups was not significantly different (P > 0.05) regardless of different STEC markers. Nonmetric multidimensional scaling of slaughter samples showed that the bacterial composition in fecal and hide samples shared the least similarity with the communities in carcass and environmental samples. Surface samples from slaughter (carcass and environmental) and boning (carcass, beef trim, and environmental) all appeared randomly plotted on the scale. This indicated that the STEC presence also did not have a significant effect (P > 0.05) on beta diversity. Although presence of STEC appeared to correlate with changes in diversity of fecal and hide bacterial communities in previous studies, it did not appear to have the same effect on other samples throughout processing.

HIGHLIGHTS

A Comparison of 16S rRNA Profiles Through Slaughter in Australian Export Beef Abattoirs

Microbial contamination of beef cattle carcases and subsequent cross-contamination during processing is inevitable and virtually impossible to prevent. The understanding of microbial contamination in the beef industry is currently limited to hypotheses based on traditional microbiological tools. Additionally, the complex structural and functional responses of beef cattle microbial communities to the fragmentation in the supply chain remain unknown. This study used 16S rRNA gene sequencing in combination with traditional microbiology to monitor and compare changes in the microbiota throughout slaughter in an integrated (abattoir A) and a fragmented (abattoir B) beef abattoir in Australia. Briefly, the primary difference between an integrated and a fragmented abattoir is that fragmented abattoirs receive cattle from multiple sources, whereas integrated abattoirs typically receive cattle that has been produced using the same production system and from a limited number of sources. The composition in the bacterial communities varied between the abattoirs, though the presence of the most predominant bacterial species within the microbiota at each abattoir was similar. Lactobacillales (2.4-56.2%) and Pseudomonadales (2.4-59.4%) most notably dominated hides, carcases, and the environment in abattoir B. In abattoir A, Bacteroidales (3.9-43.8%), Lactobacillales (0.0-61.9%), and Pseudomonadales (0.5-72.1%) fluctuated but generally shared the dominance over the rest. Combined results of total viable count (TVC) and 16S rRNA gene profiling indicated that an upward hide pulling system adopted by abattoir B may lead to increased transmission of hide contaminants to post-hide pull carcases. Abattoir B had 3.2 log₁₀CFU/cm² reduction from hide to carcase, where abattoir A had 4.5 log₁₀CFU/cm² reduction. The findings from this study indicated that common beef-associated microbiota exist in varying composition in Australian abattoirs, and 16S rRNA amplicon sequencing is a powerful tool to understand in-depth movement of microbial contaminants.

Microbial Contamination Level Profiles Attributed to Contamination of Beef Carcasses, Personnel, and Equipment: Case of Small and Medium Enterprise Slaughterhouses

The microbial contamination level profiles (MCLPs) attributed to contamination of beef carcasses, personnel, and equipment in five Kenyan small and medium enterprise slaughterhouses were determined. Aerobic plate counts, Enterobacteriaceae, Staphylococcus, and Salmonella were used to determine contamination at four different slaughter stages, namely, dehiding, evisceration, splitting, and dispatch. Microbiological criteria of the four microorganisms were used to score contamination levels (CLs) as poor (0), poor to average (1), average (2), or good (3). MCLPs were further assigned to carcasses, personnel, and equipment at each stage by summing up the CL scores. The CL score attributed to aerobic plate count contamination was 2 or 3 for carcasses but 0 for personnel and equipment in almost all slaughterhouses. A score of 0 on carcasses was mostly attributed to Enterobacteriaceae at evisceration and to Salmonella at dehiding and evisceration. In addition, a score of 0 was mostly attributed to Staphylococcus contamination of personnel at dehiding. A score of 3 was attributed mostly to Enterobacteriaceae on hands at splitting, whereas a score of 2 was mostly attributed to the clothes at dehiding and evisceration. A CL score of 3 was mostly attributed to Enterobacteriaceae and Salmonella contamination of equipment at dehiding and splitting, respectively. Although CLs attributed to contamination of carcasses, personnel, and equipment ranged from 0 to 3, the maximum MCLP score of 9 was only attained in carcasses from two slaughterhouses at dehiding and from one slaughterhouse at dispatch. There is, therefore, a lot of room for small and medium enterprise slaughterhouses to improve their food safety objectives by improving food safety management systems at the points characterized by low CL scores.

Effects of long spray-chilling on water pocket development in ribeyes

Water Pocket (WP) is a defect on beef that may lead to significant economic losses. Our hypothesis is that longer spray-chilling time increases WP incidence on ribeyes (M. longissimus thoracis). Ribeyes (28,801) were visually evaluated for the presence of WP after 24 or 72h of spray chilling. Additionally, 252 beef sides were evaluated prior to chilling to predict WP development after 24h of spray chilling. Also, the 12th rib fat thickness was measured on 313 sides and the sides were assigned to two categories of WP or no WP to evaluate fat thickness as an indicator for WP. Subcutaneous fat softness is not related to WP development, longer spray-chilling does not increase the incidence of WP in ribeyes, and thinner subcutaneous fat is an indicator for WP development.