Date of Graduation

5-2024

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Agricultural, Food and Life Sciences (PhD)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Kristen E. Gibson

Committee Member

Jennifer C. Acuff

Second Committee Member

Aurelie M. Poncet

Third Committee Member

John C. Pijanowski

Keywords

3D Food Printer;dishwasher;Listeria monocytogenes;Salmonella enterica;storage;Tulane Virus

Abstract

The burgeoning field of 3D food printing introduces opportunities for customizing the physicochemical properties of food, offering tailored solutions in color, shape, and texture. Despite its potential, the implications of this technology on food safety, particularly the efficacy of manufacturer-recommended cleaning protocols for stainless steel food ink capsules, the transferability of pathogens from a contaminated food ink capsule into the food ink based on macronutrient composition of the food, and the impact of storage conditions on pathogen viability, have not been thoroughly investigated. This dissertation provides a comprehensive analysis of these aspects, focusing on the control of foodborne pathogens and the survival of pathogens in 3D printed foods under various conditions. Through a series of experiments, this study evaluates the effectiveness of different cleaning methods—manual washing (MW), dishwasher speed cycle (DSC), and dishwasher heavy cycle (DHC)—Salmonella Typhimurium, Listeria monocytogenes, and a human norovirus surrogate, Tulane virus, in scenarios mimicking real-life usage with various soil matrices. The findings reveal that soil composition and cleaning protocol significantly affect the reduction of pathogen loads. The DHC emerged as the most effective cleaning method, substantially reducing pathogen presence, while the study also highlights the importance of capsule placement within the dishwasher for optimizing cleanliness and minimizing food safety risks. Additionally, the research delves into the macromolecular composition of food inks and its impact on pathogen transfer rates from capsules to printed food. A notable discovery was that complex food ink mixtures resulted in lower pathogen transfer rates compared to single-component food inks, suggesting that the matrix composition can influence food safety risks in 3D printed foods. The investigation extends to examining the survival of pathogens and a norovirus surrogate under various storage conditions—temperature, duration, and method (pre- vs. post-printing). The study uncovers minimal differences in the survival rates of bacterial pathogens across different conditions, indicating that storage method and temperature might play a less critical role for low water activity foods such as a protein cookie food ink. However, significant reductions in Tulane virus in the protein cookie food ink were observed under specific conditions, providing crucial insights for the development of guidelines for the safe handling and storage of 3D printed foods. The findings communicated within this dissertation underscore the complexity of ensuring food safety in the context of 3D food printing. It highlights that depending on the step in the 3D food printing process, various factors, including the soil matrix, cleaning protocol, capsule placement, food ink composition, and storage conditions, significantly influence the cleanability of capsules and the viability of foodborne pathogens.. These insights are invaluable for consumers, restaurants, the food industry, and regulatory bodies, as they navigate the challenges of implementing 3D food printing technologies safely. By advancing understanding of these critical factors, this research will contribute to the formulation of best practices and guidelines that promote the safe use of 3D food printers, thereby enhancing consumer safety in this innovative field.

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