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Access Type

Open Access Thesis

Document Type


Degree Program

Food Science

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



Human norovirus (HuNoVs) are the most common enteric pathogen around the world that cause ~50% of foodborne illness of disease outbreaks annually. HuNoVs are the member of the Caliciviridae family, which consist of small (38 nm), unenveloped, single stranded RNA (ssRNA) viruses. Norovirus are divided into 5 genogroup (GI, GII, GIII, GIV, GV, GVI and GVII). The GI, GII, and GIV cause human illness, in addition, GII.4 genotype cause the most human disease. Due to HuNoVs are difficult cultured in vitro, the cultivable HuNoVs surrogates have been widely studied. Recently, some studies have been conducted with HuNoVs surrogates, for example bacteriophage MS2. MS2 is conservative surrogate for nonenveloped viruses which there is a close relationship to the behavior of HuNoVs, thus we can examine the infection control measures for HuNoVs. Despite plenty of treatment method been done on testing antiviral effect on bacteriophage MS2, for example UV inactivation, steam ultrasound and antimicrobial etc., plant-based nanoemulsion treatment has yet to be explored. Carvacrol is a major component of oregano essential oil and is responsible for their antimicrobial activity on the growth of various microorganism. In this study, carvacrol nanoemulsions were formed by using the spontaneous emulsification for testing the nanoemulsion stability (14 days shelf life study on its droplet size and particle charge) and antimicrobial activity.

In carvacrol nanoemulsion 14 days shelf life test, the droplet size and particle charge stay stable at three different treatment environments (4°C, 20°C and 37°C). The results proved that nanoemulsion (was formed with surfactant agents and medium-chain triglycerides) is stable system that gives consistent droplet size and charge. Although, the low antimicrobial activity was investigated at carvacrol nanoemulsion, the strong antimicrobial effects have been found when carvacrol or carvacrol combined with ionic surfactant of treatment on MS2 and Escherichia coli. Taken together, in the wake of growing consumer demand for different “natural” products in a number of industries, our study broadly informs the development and study of functionalized carvacrol active compound that can not only provide beneficial health for human but can also examine antimicrobial efficacy of control measures for public health.


First Advisor

Matthew D. Moore