Canada's National Beef Quality Audit at Retail and Processing

Background

Note: due to COVID19, the research team was unable to access commercial beef processing facilities to conduct the intended Beef Quality Audit. As a result, the objectives were revised to address other beef quality questions relevant to Canada’s beef industry that could be answered in the research facilities they could access.

For decades, North America’s beef industry has used high voltage electrical stimulation (HVES) in beef carcasses to improve tenderness. But HVES may be less effective in today’s heavy carcass, so, alternative electrical stimulation methods need to be evaluated. 

Canada’s beef industry has supported the development of camera-based Computer Vision Systems (CVS) to objectively assess carcass yield and quality grade. This technology is currently in use in commercial beef processing facilities, but it may also be able to assess tenderness, identify dark cutters, and yellow fat. 

The beef industry has made tremendous advancements in preventing or removing pathogenic and spoilage bacteria from the surface of the carcass and beef cuts. However, these interventions are not effective against bacteria that may be contained within lymph nodes. This may present an opportunity to (re)contaminate ground beef if pathogens are found within the lymph node.  

Canada has conducted Beef Quality Audits in 1995, 1999, 2010/11 and 2017/18. Data from these audits present an opportunity to examine changes in carcass grades and defect prevalence data and evaluate how our industry has responded to market pressures over the past three decades. 

Objectives

• To develop a constant current electrical stimulation (CCES) system, which varies the voltage dependent on carcass impedance, and evaluate its efficacy on meat quality and palatability of finished steers. 
• Validation of CVS algorithms and threshold cut offs for tenderness, dark cutters, and yellow fat carcasses. 
• Explore the prevalence of Salmonella and the microbiota of lymph nodes in cattle at slaughter. 
• To conduct a benchmark comparison of the four beef carcass quality audits (1995, 1999, 2012/11, 2017/18), and provide insight into how altering management strategies, socio-economic, and political factors may have contributed to some of the trends observed. 

What They Did

In total, 101 crossbred steers within a wide range of hot carcass weight (353-557 kg) and fatness (3-38 mm) were used. After slaughter, one carcass side was subjected to CCES at 45 min post-mortem whereas the other side was non-CCES (Control). Muscle, pH, colour, and shear force were measured in the ribeye at several ageing times. Sensory analyses were performed by trained panelists. Bacteria were evaluated on both carcasses and ribeye steaks. 

CVS data from previous research initiatives were used to validate measurement thresholds and evaluate the prediction accuracies for identifying guaranteed tender, dark-cutter, and yellow carcasses. 

Lymph nodes and hides of 80 slaughter cattle were assessed for Salmonella, Shiga toxin-producing E. coli (STEC), and overall microbial composition using culture-based and sequencing-based methods. 

Trends in Canadian carcass and beef quality traits over the last two decades were analyzed.

What They Learned

CCES appears to reduce meat pH and shear force values and improved meat colour, tenderness and texture characteristics more effectively than HVES, but did not affect the composition of the microbiota on carcasses or meat. 

CVS correctly identified 92% of tender carcasses (< 9.6kg shear force) but had a harder time correctly identifying tough carcasses (13% of tough (> 9.6 kg shear force). The yellow fat and dark cutting algorithms were more difficult to validate, simply because none of these finished carcasses graded B2 (yellow) or B4 (dark). However, no A-grade carcasses were misidentified as B2 or B4.  

Bacteria were found in more than 80% of lymph nodes, but neither Salmonella or STEC were found. 

Comparisons across the four NBQAs showed consistent increases in carcass size, external fat cover, yield class, and quality grades. Brands, horns, and bruises have steadily declined, but liver abscesses and tag have steadily increased. 

What It Means

The CCES prototype developed and tested in this project may be a promising way to improve meat quality and tenderness in heavy carcasses.  

CVS is already widely implemented in beef processing facilities. This study suggests that this existing technology may have broader uses in identifying tenderness, dark cutters, and yellow fat at line speed. 

No Salmonella or STEC were found in the lymph nodes examined in this study. Further characterization of lymph node microbiota will help assess whether any of the other microbes found are a potential food safety or spoilage concern.  

Beef quality trends are driven by a complex combination of economics, genetics, environmental conditions, feed and ration management, societal pressures, labor shortages, cattle supplies, and infrastructure costs.   

New systems to monitor beef quality attributes in real-time could facilitate much more rapid improvements in beef quality in the future.