Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food Science and Human Nutrition


Food Science and Technology

First Advisor

Angela . Shaw


A large portion of fresh produce is consumed raw, and likewise, there have been many cases of foodborne illnesses associated with it. The contamination can occur at any point during the farm to fork continuum and may come from poor agricultural practices at the farm, deficit knowledge of food safety concerns among growers, and/or various physical, chemical, and biological hazards in the food supply chain. Agricultural water is a known vector for the transfer of foodborne pathogens onto fresh produce and has been implicated in recent foodborne outbreaks. Monitoring and management of microbial quality of agricultural water is a requirement under the Food Safety Modernization Act Produce Safety Rule (PSR). The water testing methods (n=9) mentioned in the PSR require no greater than a 6-hour time frame between the collection of the water sample and the initiation of analysis. This 6-hour timeframe is unrealistic for many farm locations in the Midwest. To address this issue, 103 agricultural water samples were collected from 60 different farms using method EPA 1603. A total of 31 samples were found contaminated with generic E. coli—mostly surface water (n=28, 87.5%). The results provide evidence that the sample-test time interval can be extended to a 24-hour time (p>0.05), which makes quantitative generic E. coli testing more accessible to growers. Cross-contamination through agricultural water has led to foodborne outbreaks with produce as well. These bacteria generally grow in four growth stages of lag, log, stationary, and death; however, research reported the fifth phase following the death phase called long term survival (LTS) cells, which have a higher resistance to antimicrobial treatments. Their sensitivity to chemical sanitizers is unknown. The study focused on quantifying the resistance of stationary and LTS cells against chemical sanitizer treatment (chlorine, sodium hypochlorite) and determined the effects of bacterial growth phase against chlorine treatment. The results reported higher resistance to LTS cells in-vitro but statistically insignificant results in the lettuce wash model (p>0.05). Monitoring the diverse routes of agricultural water contamination is critical to ensure the safety of fresh produce and to ensure that more intensive measures are required in the food supply chain to protect public health.

Copyright Owner

Manreet Singh Bhullar



File Format


File Size

113 pages

Included in

Food Science Commons