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Document Type

Campus-Only Access for One (1) Year

Embargo Period

11-8-2017

Degree Program

Food Science

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2018

Month Degree Awarded

February

Abstract

Microbial cross-contamination remains an on-going challenge in the food sector despite implemented sanitation programs. Antimicrobial coatings with inherent self-sanitizing properties have been explored to enhance current cleaning practice and support food safety. Prior work has demonstrated successful incorporation of dual antimicrobial characters, cationic polymers and N-halamines, into one coating system. In addition to the rechargeable nature of N-halamines, the coating was reported to exhibit biocidal effects due to the inherently antimicrobial cationic moieties and the chlorinated N-halamines. However, while these polymer coatings were able to retain antimicrobial activity after repeated chlorination, signs of hydrolysis was observed for the N-halamine bonds, indicating potential issues for long-term usage. Herein, we introduced varied molecular weight cross-linkers in an adaption of the established fabrication method to evaluate cross-linker molecular weight (styrene maleic anhydride (SMA) of 6, 8, 120, 250 kDa) influence on surface properties of the coating.

All antimicrobial polymer coatings exhibited similar FTIR spectra, with a prominent absorption band at ~1650 cm-1 suggesting successful cross-link of the polyethyleneimine and SMA. Surface concentration of primary amines ranged from 350-900 nmol/cm2, and N-halamines from 90-130 nmol/cm2. Surface energy decreased with increasing molecular weight of SMA, but were not statistically different from one another. In the end, optimal cross-linker molecular weight was determined based on antimicrobial performance, where the coated PPs with 6 kDa SMAs demonstrated enhanced biocidal effects against E. coli O157:H7 in its chlorinated form. Further, the antimicrobial coating demonstrated efficacy of ~3 to >5 log reductions of microbial load in its unchlorinated and chlorinated form against E. coli O157:H7, L. monocytogenes, and P. fluorescens. Storage studies support the stability of the chlorinated halamines, with full retention of chlorinated N-halamines over a 24 h study (representative of time between sanitation cycles). These results support the potential application of this antimicrobial polymer coating in food processing and handling operations, in support of reducing cross-contamination of spoilage and pathogenic microorganisms.

First Advisor

Lynne A. McLandsborough

Second Advisor

Amanda Kinchla

Third Advisor

Julie M. Goddard

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