Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

Document Type



Foodborne microorganisms can be beneficial to humans or cause disease. Salmonella is one of the most causative foodborne disease outbreaks in the U.S.A. Salmonella has been detected in surface water used in irrigation, and can survive for weeks to years in water. The purpose of the study was to detect low levels of Salmonella spp. by comparing surfactant modified zeolite (SMZ) filtration and Activated Carbon (AC) filtration with the Environmental Protection Agency (EPA) method 1200. Also, to determine the generic E.coli counts and if there was a direct correlation of Salmonella to generic E. coli in irrigation water. The EPA method detected Salmonella at lower levels compared to the SMZ and AC methods. Generic E.coli counts for surface water had no significant difference between EPA 1603 and Quanti-Tray methods (p value > 0.05). Whereas, Generic E.coli counts for surface and sediments using Quanti-Tray method had significant difference (p value < 0.05). Base on the Food Safety Modernization Act for agricultural water’s rule, the generic E.coli were higher than 126 > CFU/100 ml which shows correlation to Salmonella in irrigation water. On the other hand, probiotics are good bacteria to consume for the digestive system. Yogurts contain the probiotic bacteria Streptococcus thermophilus and Lactobacillus bulgaricus. In order to protect yogurt from contamination and spoilage, an antimicrobial called Myrrh was added to the yogurt and studied for 5 weeks. Myrrh is a natural flavoring substance approved by FDA as a food flavor. The objective was to determine the effect of myrrh on S. thermophilus and L. bulgaricus counts in peptone water and in the yogurt matrix. The pH, titratable acidity, viscosity, viii and color of yogurts measured for 5 weeks. Myrrh dispersion was prepared and incorporated into yogurt at a 1% v/v level. A control with no myrrh was also prepared. There was significant difference between S.thermophilus counts and L. bulgaricus counts in yogurt myrrh and control yogurt. Only minimum changes during storage were observed for color. With little to no change in yogurt pH and titratable acidity, and viscosity yogurt culture bacteria can survive in the presence of myrrh within yogurt.



Committee Chair

Janes, Marlene E.



Available for download on Wednesday, October 23, 2024