Efforts to Promote Quality and Safety in Beef Abound

Validation involves two major components, Dr. Castillo adds. The first step is to provide scientific proof that the antimicrobial intervention (a lethality process, for example) will achieve its intended purpose of preventing, reducing, and/or eliminating the hazard in the food processing operation. The second step is to ensure that the process will consistently meet the critical limits of the parameters that would impact the efficacy of the antimicrobial treatment.

Of the various alternatives designed to validate a pathogen control protocol, conducting in-house experiments is best, Dr. Castillo advises. “Carcasses should be inoculated with a USDA Food Safety Inspection Service (FSIS) inspector-approved harmless surrogate organism that represents pathogens,” he advises. “Then, trials should be run using the plant’s established decontamination processes.”

As an alternative to in-plant experiments, Dr. Castillo recommends reviewing a peer-reviewed document that represents the process in question to procure details about the efficacy of the procedure, notably the log reduction of the pathogens. “The International Commission on Microbiological Specifications for Foods and Codex Alimentarius are two excellent resources for validation guidelines,” he says.

STEC-Reduction Studies

Dr. Castillo has supervised a number of research projects at TAMU evaluating the efficacy of different antimicrobial interventions. In the most recent study, his team used either conventional spray or handheld electrostatic spray to apply treatments for reducing Shiga toxin-producing Escherichia coli (STEC) on fresh beef surfaces.

In results published in 2019, Dr. Castillo’s team found no advantage in the use of electrostatic spray to reduce STEC on cold beef. The greatest reductions in STEC were achieved by lactic acid with conventional spray. Lauric arginate ester was the second-best antimicrobial agent at reducing STEC. Lactic acid reduced pH on the beef surface significantly. “The significance of these findings for beef processing is that beef slaughter establishments do not need to invest in new equipment to enhance the effectiveness of their carcass interventions, and that lactic acid, an antimicrobial already being used frequently, is one of the most effective FSIS-approved compounds available,” Dr. Castillo says.

Aerosol Pathogen Transport

Sanitation continues to be a significant food quality and safety concern in U.S. beef processing plants, Dr. Castillo points out.

Under the sanitation umbrella, in another study published in 2019, Dr. Castillo led a TAMU team that combined bioaerosol concentration measurements with computational fluid dynamics modeling to track and verify bioaerosol transport in beef slaughterhouses.

Aerosolized bacteria have been recognized as a threat to human health and the shelf life of food, Dr. Castillo says. “In beef processing facilities, the majority of harmful bacteria are introduced by the cattle, and these bacteria are later aerosolized during the hectic operations in the kill floor area,” he adds. “But, then, heating, ventilation, and air conditioning (HVAC) systems can transport these microorganisms throughout the plant if it is not adequately designed. Our study detected significant bioaerosol concentrations, STEC, and Salmonella in the plants we sampled.”

“The microbiomes at the kill floor showed a high relative concentration of Enterobacteriaceae, potentially including STEC,” Dr. Castillo reports. “Salmonella was detected in the kill floor and de-hiding area samples. And, in some instances, the same pathogen was detected in the chiller room. Bioaerosol pathogen counts increased with each subsequent day of our study, indicating that pathogens can remain suspended in the plant’s air even after cleaning and sanitizing processing surfaces. Our results indicate bioaerosols were transported from the kill floor toward chiller containing final food product.”

The take home message, Dr. Castillo says, is that airflow created from inadequately designed and laid out HVAC systems can have a significant effect on the spread of bioaerosols. “We determined that, depending on plant size and layout, sanitation can be improved with new, improved displacement ventilation designs,” he adds.

Addressing Biosecurity-Related Health Threats

In 2019, Colorado State University (CSU) in Fort Collins spearheaded the launch of the Coalition for Epi Response, Engagement and Science (CERES), an entity designed to protect and defend the U.S. agricultural industry, including beef, against global health threats, according to Keith Belk, PhD, CSU’s department head of animal sciences.