Theses and Dissertations

Issuing Body

Mississippi State University


Silva, Juan L.

Committee Member

Matta, Frank B.

Committee Member

Williams, J. Byron

Committee Member

Schilling, M. Wes

Committee Member

Kim, Taejo

Date of Degree


Document Type

Dissertation - Open Access


Food Science and Technology

Degree Name

Doctor of Philosophy (Ph.D)


College of Agriculture and Life Sciences


Department of Food Science, Nutrition and Health Promotion


Environmental samples from food processing facilities and production (farms) were taken and analyzed for the presence of indicator organisms and Salmonella spp. on food contact (FC) and nonood contact (NFC) surfaces. Salmonella was isolated from both FC and NFC surfaces of a fruit and catfish-processing plant environment, but not from a dairy processing plant or from produce packaging facility environments. Scatter plots did not show a relationship between indicator organisms and the presence of Salmonella in processing environments, regardless of the facility/environment. Salmonella ser. Gaminara and Salmonella ser. Give were prevalent in the fruit processing environment. Persistence could not be determined, as Salmonella was not detected during subsequent samplings. Two modifications of the Rappaport Vassiliadis (RV) enrichment step were evaluated and compared to the standard enrichment methods for the recovery of Salmonella. Detection rates ranged from 10.2% to 21.2% and 22.3% to 31.9% for aquaculture and sweet potato farming environments, respectively. Salmonella ser. Newport and Salmonella ser. Javiana were prevalent in the sweet potato farming environment, whereas Salmonella ser. Newport and Salmonella ser. Hartford were prevalent in the aquaculture environment. PFGE analysis revealed clusters with a high degree of genetic similarity (greater than or equal to 90%) from the fruit-processing, aquaculture, and sweet potato environments, suggesting that they represented the same strain isolated from different sampling points. Molecular characterization of isolates revealed potential contamination paths to catfish and sweet potatoes.