Doctoral Dissertations
Date of Award
8-2020
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Food Science
Major Professor
Qixin Zhong
Committee Members
Douglas Hayes, Jennifer Richards, Alison Buchan
Abstract
Essential oils (EOs) are natural antimicrobials that can be used to develop intervention strategies to inhibit pathogens, but EOs are lipophilic. Colloidal systems, such as microemulsions, are needed for food industry applications. This dissertation focused on the development and characterization of a microemulsion composed of cinnamon oil (CO, Cinnamomum zeylanicum) and orange oil (OO, Citrus sinensis) to be used against Salmonella Enteritidis H4267 biofilms formed on stainless steel disc surfaces.
First, the antimicrobial activity of CO and OO against S. Enteritidis H4267, either used in combination or in a microemulsion system, was determined. CO had a greater antimicrobial effect on S. Enteritidis H4267 when used in combination with OO than when individually (p® 20, 1% and 5% CO-OO (9:1) were transparent, thermodynamically stable microemulsions that had bactericidal activity on S. Enteritidis H4267.
The second objective investigated the biofilm forming ability of S. Enteritidis H4267 and determined a method to remove biofilms on stainless steel disc surfaces. S. Enteritidis H4267 was determined to produce curli and cellulose indicative of biofilm development, and biofilms were formed on stainless steel disc surfaces. Sonication in 0.1% (w/v) peptone water for 30 sec effectively dislodged biofilms from disc surfaces without causing extensive cell death.
Biofilms were treated with microemulsions and emulsion controls for 5 minutes to determine the antimicrobial activity in the third objective. The 2% SL, 5% CO-OO (9:1) microemulsions displayed the greatest antimicrobial activity against biofilms.
This study demonstrated that OO enhances the bactericidal activity of CO when in an oil or microemulsion system, and co-encapsulated oils in microemulsions could be developed for antimicrobial delivery systems. Further research into developing microemulsions with positively charged droplets and with greater microemulsion exposure time should be investigated.
Recommended Citation
Vuia-Riser, Jennifer, "Microemulsions of cinnamon and orange oils as an antimicrobial delivery system for Salmonella biofilms on stainless steel. " PhD diss., University of Tennessee, 2020.
https://trace.tennessee.edu/utk_graddiss/6895
Comments
I submitted this dissertation to the Publications section of TRACE on June 5 in error. I received an email on June 16 that I had submitted it to the wrong place in error. Please let me know if I can still graduate on time for summer 2020. Thank you.
07/16/2020: I made edits to the document based on the comments I received on my 2nd review. When I make changes to the "References" section to have the spacing be double-spaced, it makes the changes, but it does not show it when I re-highlight the area and check that the spacing is correct. I have saved, closed, and re-opened the document at least 3 times, and I cannot get the document to say that I have made the spacing near "References" be double-spaced. I promise I have made it double-spaced. I have no idea why it is saying it is not double-spaced, but it is. I highlighted my whole dissertation several times, went to paragraph, made it double-spaced, saved it, and it still says that the spacing is not double-spaced. I don't know what else to do.
07/25/2020: I made the edits based on the comments back. I went back through and individually changed the heading spacing and tried to match it to the rest of the document. I really hope I got all of them. I couldn't find anywhere else that I could have missed them, and I'm starting to get worried I won't get this approved by the July 20th deadline. Please let me know if my manual/individual changes didn't save. I don't know what else to do!