Jorge Yagual

Jorge Yagual

University of New Hampshire

Animal & Nutritional Sciences


Mentor: Steve Torosian, Ph.D., Department of Microbiology

Pathogen Exposure of Consumers by Foodstuffs and Potential Methods to Lower Exposure

Food-borne illnesses are the result of ingesting pathogen-contaminated foods. Classified as moderate or severe, food-borne illnesses are characterized by symptoms such as chills, fever, muscle fatigue, diarrhea, and in severe cases, bloody diarrhea and/or thrombosis. In an effort to find solutions designed to lower the risks of contracting a food-borne illness, scientific studies have looked at the amount of pathogen exposure of consumers by foodstuffs and the levels at which exposure becomes detrimental to human health. Similar studies have been conducted to develop potential methods to lower pathogen load in foodstuffs.

The purpose of this study is to investigate the level of pathogen exposure of consumers by foodstuffs and develop potential methods to lower exposure. Tested foodstuffs were collected from two local markets and from the dining hall of a school in the Durham area. Eight different foods1 were tested in five separate weekly sessions. Twenty grams of each food was homogenized with eighty milligrams of dilute 1% tryptone broth. Homogenate solutions were pipetted into serial dilutions. Solutions were allowed for enrichment of coliforms, by evolution of gas in Durham tubes. Confirmation of Escherichia coli was performed by plating onto EMB agar. Positive coliforms were screened for E. coli O157:H7 on rainbow agar-selective/differential agar for E. coli 0157:H7. Further, dilutions of homogenate were placed on plate T-Soy agar for enumeration of aerobes. Dilutions of homogenate were plated on Salmonella Shigella agar, which is selective and differential for these organisms. Sub-sample of homogenate was filtered, sterilized, and inoculated onto monolayers of Buffalo Green Monkey Kidney Cells (BGMK) for enumeration of possible viral contaminants. One percent Sodium hypochlorite solution was a treatment method used for decontamination, but this method showed negative effects on foodstuff tissues. Various decontamination agents were used including UV light exposure and dilutions of vinegar, garlic, and herbs. After treatment, the foodstuffs were subject to the same assays as untreated foodstuffs. Results from this experiment showed that a wide variety of foods, ranging from fruits and vegetables to ground beef, tested positive for panthogenic and toxigenic bacterial strains. The universal presence of bacteria on tested foods suggests that there is a need for more thorough decontamination procedures on the part of producers, food handlers, and consumers. The results and decontamination methods showed in this experiment may be useful information to the general public and those in charge of developing food safety materials.

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