Date of Award:

5-2025

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biological Engineering

Committee Chair(s)

Luis J. Bastarrachea

Committee

Luis J. Bastarrachea

Committee

Marie K. Walsh

Committee

David W. Britt

Abstract

Current food packaging materials are often non-biodegradable and harmful for ingestion, which poses a threat to the environment and public health. Thus far, the dangers of microbial contamination of food on human health have outweighed the risks associated with using these conventional packaging plastics. A possible solution to these issues is to use a combination of innovative materials and microbial inactivation methods that can potentially both reduce plastic waste and combat harmful microorganisms. In this study, two antimicrobial, biodegradable composites were developed and tested for their ability to inactivate two types of bacterium, Escherichia coli K12 and Listeria innocua, in apple juice in combination with either mild heat or ultraviolet light exposure. Efficacy of each composite was evaluated alone and in combination with either mild heat (50 °C) or ultraviolet (UV-A) light. The partially biodegradable composite reduced L. innocua by over 99.998% when used with either mild heat or UV-A, and reduced E. coli by up to 99.8% and 99.99%, for UV-A and mild heat, respectively. Surface analyses confirmed that the composite remained physically and chemically stable despite these treatments. The fully biodegradable composite reduced E. coli populations by up to 99.8% under UV-A and 99.9% with mild heat, while L. innocua decreased by more than 99.998% for both. Water vapor permeability and mechanical testing showed this material had properties comparable to conventional plastics, however, its oxygen permeability was higher which may affect its usefulness in some practical food packaging applications. It exhibited lower thermal property values compared to the commonly used biodegradable plastic, PLA, which indicates lower temperatures required for processing of the material, reducing energy requirement and cost. These findings demonstrate the potential of combining biodegradable antimicrobial materials with other preservation techniques to improve food safety while reducing negative environmental impact.

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