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Location of Salmonella in poultry fat intended for use in pet food and the influence of fat's physical characteristics on Salmonella prevalence and growth




Kiel, Rinara C., author
Belk, Keith E., advisor
Woerner, Dale R., committee member
Martin, Jennifer N., committee member
Hess, Ann M., committee member

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This study was conducted to: (i) utilize fluorescently-tagged Salmonella to assess distribution of Salmonella in a rendered fat matrix; (ii) assess the influence of post-inoculation time and moisture content on distribution of fluorescently-tagged Salmonella in rendered poultry fat; and, (iii) evaluate the impact of post-inoculation time and physical parameters (i.e., impurity level and moisture content) on survival of three Salmonella serotype strains in rendered poultry fat stored at 25˚C or 45˚C. Three studies, designated as Study I(a), I(b) and II were conducted to address the objectives. In Study I(a), a green fluorescent protein (GFP)-expressing strain of Salmonella Typhimurium was used to visually and microbiologically map the organism within warmed (45˚C) poultry fat formulations comprised of a low impurity level (<0.2%) and three moisture contents (low: 0.5%; medium: 2.2%; high: 4.5%). In Study I(b), using the same fat formulations as in Study I(a), survivability of GFP-expressing Salmonella was compared in samples that were either stored at 25˚C or 45˚C. In Study II, survivability of three Salmonella serotype (Enteritidis, Senftenberg, Typhimurium) strains was compared in fat formulations of two impurity levels (0.5%, 1.0%), three moisture contents (low: 0.5-0.7%; medium: 2.1-3.0%; high: 3.9-4.8%) and two temperatures (25˚C, 45˚C). Surviving populations of Salmonella Typhimurium and their location in a rendered fat matrix were achieved for each treatment combination (Study I). For Study I(b) and II, death/survival/growth curves were developed and comparisons among factors of time, temperature and moisture contents were made. In conclusion, the best option for the rendering industry to control Salmonella in poultry fat it is to control multiple factors when storing the final product, more specifically, low impurity poultry fat with low moisture content that is stored at a high temperature (45˚C and above) for a period of time would effectively control Salmonella contamination in poultry fat. Preventing recontamination is another crucial point for the rendering facilities, in that matter, GMP is essential, sanitation conditions that will not allow contamination and biofilm formation should be implemented and validated, as appropriate cleaning with scrubbing in holding bins, storage tanks, floors, walls, trucks, everything that have contact with the product.


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poultry fat


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