Hart Bailey: risk factors for Salmonella through the chiller

 My southern gentlemanly friend, Hartford Bailey, wrote a decent piece for meatingplace.com.

Hart invited me down to Mississippi State University about 2000, I have pictures which involve a lot of cowbell at a baseball game but I can’t seem to find them because, as Hart and I both enter our 50th year, I lose more stuff than I can remember.

So here’s the raw Hart.

In January 1998, the United States red meat and poultry industry changed forever the manner in which inspection was conducted during processing. The implementation of the Hazard Analysis Critical Control Point (HACCP) inspection process transformed a system that had originated nearly a century earlier. The new regulations stated that the “hazards analysis shall include food safety hazards …before, during, and after entry into the establishment.”
Interestingly, the political impetus for both the original inspection system and new one were similar.

Lack of data affected decision-making

Initially, the intent of the regulatory effort was to maintain pathogen control from within the plant. However, soon after the first Salmonella performance sets were completed, the debate of pre-harvest pathogen control began in earnest.

Attention turned to all aspects of the production and growout process promoting a variety of pathogen control products and practices, yet the research data available to assist in making sound risk management decisions was noticeably lacking.

Subsequently, in July of 2011, new regulations came into effect that reduced the performance standards for Salmonella from no more that 12 of 51 positive carcass rinses to no more that 5 out of 51. Additionally, a performance standard for the pathogen Campylobacter was initiated for poultry. With these increased regulatory standards the necessity for sound applied research is needed as much as ever by the poultry industry.

The pre-harvest areas researched for pathogen control have included management procedures, feed additives, competitive exclusion and probiotics, drinking water additives, litter treatments, vaccinations and hatchery procedures all the way back to the eggs.

In the processing plants, post-harvest pathogen control has made great strides compared to those seen at the initiation of HACCP in January 1998. However, the important question that still must be addressed is: What is the effect of pathogen load of the birds as they present at the loading dock on their pathogen status as they exit the chill tank?

The focus of our research group’s work has been based on the hypothesis that there are measurable risk factors in production and processing that impact the occurrence of the pathogens Salmonella and Campylobacter on broiler carcasses at the end of the chill tank. Of course it is at this point that FSIS exercises its regulatory authority as far as conducting carcass rinses in sampling for the pathogens.

In accessing risk factors of any kind, the legitimacy of the assessment is only as good as the sampling plan and testing paradigm upon which the risks are evaluated. It is essential to utilize the most sensitive culture method for determining Salmonella status of samples from the production environment. Another consideration is the determination of the best type of sampling method (i.e., grab samples of litter or drag swab) and the efficacy of the culture method with the matrix that is being evaluated (i.e., litter, water, feed).

A research project was designed so that it was a longitudinal study with repeated sampling of 76 broiler flocks from 38 different farms as they moved through production and processing continuum. The primary goal of the project was to measure associations between various risk factors and the detection of Salmonella and Campylobacter at various sampling points, especially the post-chill carcasses.

Environmental samples were collected from the chicken houses prior to the chicks arriving and the sampling of the flocks continued through to the end of the chill tank. In total more than 21,000 samples were analyzed for Salmonella. More than 5,000 of the samples were positive for Salmonella, with 70 different serotypes.

Observing the overall prevalence at different sampling points or sample types gives a summary of the occurrence of Salmonella at each sample point or type. However, overall prevalence does not explain how the different sampling points are related. For example, if there is a higher level of Salmonella in the litter on the day of placement, is the flock more or less likely to have a higher level of Salmonella in post-chill carcasses?

An analysis of the data indicated that the Salmonella status of litter following the harvest of the birds and the litter’s status prior to placement of the birds were the best predictors of the presence of Salmonella as the carcasses exited the chill tank. Based upon those results, further analysis indicated that the likelihood of Salmonella recovery from the litter on the day the chicks are placed in the house is associated with the use of fresh top shavings or completely new litter and the presence of wood or wooden covered base on inside wall in the house.

From these results it was concluded the Salmonella status of broiler carcasses in the processing plant can be associated with recovery of Salmonella from samples collected pre-harvest. Further, we concluded that the immersion chill tank disrupts some of the relationships between processing plant and pre-harvest samples in the control of Salmonella, thus demonstrating its effectiveness in pathogen control.

The type of field research that is required to address the pre-harvest pathogen control for the poultry industry is very consuming of time, human and material resources. Continued work in this area is essential to the viability of the industry and support for this type of research is still needed to produce and validate products and processes that help control food borne pathogens that may be present in the field.