Doctor of Philosophy (PhD)


School of Nutrition and Food Sciences

Document Type



Chitosan is a polymer derived of the deacetylation of chitin that is one of the most abundant material in nature. Chitosan solutions applied as edible coatings, and dipping solutions have shown positive results in the extension of shelf life on seafood and meat products. The purpose of this study was to evaluate the antimicrobial activities of a newly invented high molecular weight water-soluble (HMWWS) chitosan against selected Gram-negative (Salmonella Typhimurium, Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae) and Gram-positive (Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus) foodborne pathogens (initial inoculation of 6.5 Log). Chitosans with 789 kDa, 800 kDa, and 1017 kDa were dissolved in aspartic acid, acetic acid, and lactic acid to obtain 1-4% w/v solutions. To analysis the antimicrobial activity of chitosan, it was coated onto the surface of food products that were inoculated with different foodborne pathogens then the food products were stored at refrigerator temperatures. The bacterial counts of samples were conducted five times during the shelf life study. The food products used during this study were ready-to-eat (RTE) Dungeness crab and RTE chicken, and shucked oysters. This study demonstrated that chitosan was effective against some foodborne pathogens. Although chitosan has been reported to exhibit more significant bactericidal effects against Gram-positive bacteria than Gram-negative bacteria, in this dissertation research, there were no marked trends in inhibitory effects of chitosan against both types of bacteria during this study. The antibacterial activity of chitosan differed depending on the concentration of chitosan solution, the solvent used to dissolve the chitosan, molecular weight, bacteria, and product tested.

Committee Chair

Janes, Marlene