Abstract
Predictive models offer food scientists, farmers, and processors tools to help identify variables that lead to an increase in the food safety risk of a product. Foodborne pathogens, such as Listeria spp., pose a major problem for the pastured poultry industry. Currently, there is a lack of understanding of what farm practices lead to higher prevalence of Listeria spp. This study constructed random forest (RF) models to predict the prevalence of Listeria spp. in pastured poultry farming environments and the final broiler product based on major farm practices and variables. Feces, soil, and whole carcass rinse samples were collected from 11 farms in the southeastern United States and evaluated for Listeria spp. presence. The preharvest sample RF model identified the time of year and age of the broiler flock at time of sampling as factors of increased probability of Listeria spp. presence in feces and soil samples. The final product RF model identified brood feed and the presence of chlorine in processing rinse water as the two most important variables associated with an increased likelihood of Listeria spp. presence. Both the preharvest RF model and final sample RF model performed well on a held-out test set, with area under the receiver operating characteristic curve values of 0.867 and 0.887, respectively. The presented models showed the usefulness of RF models in a food safety context. Both RF models will help pastured poultry farmers and processors guide control strategies to manage Listeria contamination in pastured poultry farms and products.
Highlights
Listeria spp. are gram-positive, ubiquitous organisms that have been found in a variety of environments, including agricultural and farming, food processing, and retail environments (Martín et al, 2014; Sasaki et al, 2014; Ahmed et al, 2015)
The current study evaluated preharvest environmental and processed broiler samples collected from pastured poultry farms from 2014 to 2017 and constructed random forest (RF) models to predict Listeria spp. prevalence based on various farm practice variables, like feed type, egg source, and broiler breed
Our model identified time of year as a potential indicator of preharvest presence of Listeria spp. on pastured poultry farms
Summary
Listeria spp. are gram-positive, ubiquitous organisms that have been found in a variety of environments, including agricultural and farming, food processing, and retail environments (Martín et al, 2014; Sasaki et al, 2014; Ahmed et al, 2015). Listeria can colonize the intestines of poultry and spread into the litter and environment through poultry feces (Njagi et al, 2004; Dhama et al, 2013). This marks a potential entry pathway into a poultry processing plant, if not controlled for. It is important for poultry producers and processors to understand what factors are most important in controlling for Listeria spp. prevalence in the environment and postharvest product of pastured poultry farms
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