Doctor of Philosophy, The Ohio State University, 2010, Food Science and Technology

It is estimated that there are over 76 million cases of foodborne illnesses caused by consumption of foods contaminated with pathogenic foodborne microorganisms in the United States each year. To minimize the incidence of pathogenic microorganisms in minimally processed foods while maintaining quality characteristics, nonthermal processing technologies are needed. High pressure processing, electron-beam irradiation and antimicrobial surface coatings are three intervention strategies that can reduce microbial foodborne pathogens when there is insufficient heat to destroy them. These technologies have the advantage of low heat or minimal thermal processing conditions, ideal for fresh food products. This research investigates the efficacy of these nonthermal techniques on nonpathogenic surrogates of pathogenic foodborne microorganisms. Chapter number 2 discloses the result of an investigation of the inactivation potential of high pressure processing on Salmonella Typhimurium inoculated commercial peanut butter samples and peanut based food matrices. Chapter 3 describes the electron-beam irradiation dosage required to pasteurize, via complete inactivation of a target non-sporeforming microorganism, fresh-cut cabbage samples inoculated with Escherichia coli K12. Chapter 4 is a study of the efficacy before and after an accelerated longevity testing of several commercially available antimicrobial surface coatings against a cocktail of Listeria innocua, Escherichia coli K12, and Salmonella Typhimurium. The findings in Chapter 2 indicate minimal reductions Salmonella Typhimurium inoculated into commercial and model peanut butter samples. Chapter 3 shows electron-beam irradiation was highly effective at reducing the indigenous and inoculated microflora present in the fresh-cut cabbage samples as seen using general plate count agar and selective differential agar to determine survival of microorganisms in both uninoculated and inoculated cabbage samples at 0, 1.0, 2.3, and 4.0 (open full item for complete abstract)

Committee: Ken Lee PhD (Advisor); Ahmed Yousef PhD (Committee Member); V.M. Balasubramaniam PhD (Committee Member); Melvin Pascall (Committee Member) Subjects: Food Science

Doctor of Philosophy, The Ohio State University, 2012, Food Science and Technology

Human norovirus remains the most prevalent foodborne pathogen, resulting in 58% of all foodborne illnesses in the United States, annually. Due to lack of successful cultivation techniques for this virus, research on intervention strategies and disinfection practices to combat this pathogen is still largely underreported. The research performed in this dissertation determined the efficacy of electron beam (e-beam) irradiation and sodium hypochlorite sanitizers at inactivating a human norovirus surrogate (murine norovirus 1, MNV-1) and compared the rates of inactivation against that of an enveloped virus (vesicular stomatitis virus, VSV). This research also attempted to determine the mechanism of viral inactivation for e-beam and sodium hypochlorite. In Chapter 2, we evaluated the efficacy of e-beam at inactivating MNV-1 inoculated to liquid model systems (phosphate buffered saline, PBS; Dulbecco's Modified Eagle Medium, DMEM) and fresh produce (shredded cabbage, cut strawberries). MNV-1 proved to be resistant to irradiation in both liquid and food samples. In PBS and DMEM, a dose of 2 kGy provided a less than 1 log reduction of MNV-1. At doses of 4, 6, 8, 10, and 12 kGy, viral reduction in PBS ranged from 2.37 to 6.40 logs, and 1.40 to 3.59 logs in DMEM. At 4 kGy (the maximum irradiation dose approved by the FDA for fresh produce), MNV-1 inoculated to shredded cabbage only experienced a 1 log reduction, and less than 1 log reduction in cut strawberries. Even at 12 kGy, MNV-1 titers were reduced by 3 and 2 logs in cabbage and strawberries, respectively. These results suggest that complex liquid media and the food matrix may protect MNV-1 from irradiation, and that viruses tend to be more resistant to irradiation than bacteria due to their small size and highly stable viral capsid. E-beam does not appear to be a feasible processing technology to inactivate foodborne viruses in food products. Chapter 3 compares e-beam's ability to inactivate the nonenveloped MNV-1 vers (open full item for complete abstract)

Committee: Ken Lee PhD (Advisor); Jianrong Li PhD (Committee Member); V.M. Balasubramaniam PhD (Committee Member); Jiyoung Lee PhD (Committee Member) Subjects: Food Science