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Author ORCID Identifier

https://orcid.org/0009-0009-8467-1752

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2023

Month Degree Awarded

September

First Advisor

Matthew D Moore

Second Advisor

Amanda Kinchla

Third Advisor

John Gibbons

Fourth Advisor

Lili He

Fifth Advisor

Indu Upadhyaya

Subject Categories

Agricultural Education | Food Biotechnology | Food Microbiology

Abstract

Food is a primary resource for survival of human beings, and it is also one of the primary resources for spread of infectious diseases. When both these factors come together it does not only cause ill effects on our health but also causes a burden on the food and agricultural industry. Through the help of science, us researchers and scientists have always tried to reduce this burden. And I hope like a drop of water in the ocean in some way my research contributes towards this. According to WHO currently in 2023 there are about 1 in 10 people falling ill due to foodborne diseases and amongst them about 420000 cases result in death and this also includes children. There are various contributing factors towards this. Cross contamination from the equipment’s used during handling and not following good manufacturing or agricultural practices are major contributing factors. Most foodborne outbreaks are caused due to raw food, and this is mainly due to the absence of a kill step such as cooking step. Foodborne illness causing microorganisms are a major concern in the food industry and this work aimed at mitigating the risks caused by them. Raw produces are commonly consumed without a kill step such as cooking, and their contamination can occur anywhere in the farm to fork production chain. One such practice of concern is one followed by many small-scale and medium-scale farmers specifically in the New England area where they disassemble regular washing machines and convert it into a centrifugation machine for spin drying produce such as leafy greens. Hence, Listeria innocua (a leading cause for foodborne deaths) was used as a model to determine the degree of microbial spread in different parts of the retrofitted machine. The work presented here suggests that there is a high possibility of risk as the microbial recovery was in high numbers when enumerated from different parts of the machine. It was also established that there a transfer to fresh produce from contaminated machine, which is a concern for Listeria as it is psychrotrophic, able to persist environmentally and forms persistent biofilms. In addition to retrofitted washing machines, this work was also aimed at determining the microbial contamination efficiency of a commercially available spin-drying machine used for drying produce such as leafy greens. The work presented here suggests that the microbial recovery was significant but lower when compared to the retrofitted machine. The main aim of this research is focused on establishing a standard sanitation operating procedure’s (SSOP’s) aimed at informing best practice to local producers. Hence, FDA and EPA recommended food contact surface approved cleaning and sanitation practices were evaluated. The results suggest a microbial reduction to below Limit of Detection (LOD) post cleaning and complete removal of the residual microorganisms post application of food contact surface approved sanitizers such as peroxy acetic acid (110 ppm) and sodium hypochlorite (200 ppm). However, interestingly, it was not possible to obtain a complete removal of the residual microorganisms post sanitation in the bottom layer of the commercial machine and this was achievable in the retrofitted machine. Human norovirus is the leading cause for foodborne illness globally accounting for 200,000 deaths annually. One considerable challenge to their sanitation control is their general resistance to many commonly used inactivation agents such as UV radiation, ethanol, and chlorine-based treatments. Researchers are increasingly working towards evaluating the potential for alternative plant-based therapies such as bioactive phytocompounds present in essential oils such as cinnamaldehyde. They are generally recognized as safe (GRAS) and is approved for food use (21 CFR 182.60) by the Food and Drug Administration (FDA) to impart flavor in numerous foods. Hence, this research aimed at investigating an alternative way to evaluate the inactivation of viruses in the environment/foods and especially on food contact surfaces. It was also important to formulate an enhanced delivery system such as cinnamaldehyde incorporated cationic nanoemulsion to ensure the disinfectant particles were able to disrupt the negatively charged viral protein. Previous work had demonstrated that restructuring disinfectants into charged nanoemulsions can enhance inactivation of bacteria and fungi, but their effect on viruses is unknown. A low energy method Phase inversion nanoemulsion formulation method was established. Shelf-life study of the nanoemulsion suggested that the optimum particle size (100nm) and ζ-potential (15nm) was achieved when the disinfectant was stored at 4°C. The virus was treated with different concentrations of nanoemulsion and plain oil (0.5% -3.5%) by suspension assay. Significantly less reduction of MS2 was observed when treated for 1 hour with cationic cinnamaldehyde nanoemulsion when compared to oil. Human norovirus is a non-enveloped virus; hence, comparative study was conducted to evaluate the efficiency of the disinfectant against enveloped virus human coronavirus-229E (HCoV-229E). Alternatively, significant reduction of coronavirus-229E was observed with treatment of cinnamaldehyde nanoemulsions even when compared to just oil. This result suggests that the efficiency of the essential oil as a disinfectant against coronavirus-229E can be increased when it is incorporated in a nanoemulsion at the appropriate concentration. These data suggest that one potential reason for the reduced efficacy against MS2 bacteriophage in comparison to coronavirus-229E could be that the nanoemulsions are too lipophilic for nonenveloped viruses regardless of the presence of hydrophobic patches on the viral capsid protein, and thus only offer benefit with enveloped viruses. Further work should be continued to determine the efficiency against actual food contact surfaces.

DOI

https://doi.org/10.7275/35986742

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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