Masters Theses

Date of Award

5-2019

Degree Type

Thesis

Degree Name

Master of Science

Major

Food Science

Major Professor

Doris D’Souza

Committee Members

Mark Morgan, Vermont P. Dia

Abstract

Food contamination from hepatitis A virus (HAV) is a great concern to food producers worldwide. Finding an innovative approach to inactivate HAV on food contact surfaces and on different produce remains a challenge. Using chemical disinfectants (e.g. chlorine) is an effective way to inactivate HAV on fomites, but it maybe unfavorable for food products. While heat inactivation of HAV remains the most efficient way to inactivate HAV when present in foods, most foodborne outbreaks of HAV are related to ready-to-eat (RTE) foods including produce which do not undergo further heating. Therefore, finding compounds with effective anti-HAV activities will be of great benefit to the food sector. In our study, oleanolic acid (OA) and ursolic acid (UA) have been investigated for their anti-HAV properties. OA at 600 μg/ml and UA at 360 μg/ml showed 2.27±0.67 and 1.33±0.35 log PFU/ml reduction after a 1 h treatment, respectively. Furthermore, to increase virus inactivation, photodynamic inactivation (PDI) was applied, which uses oxygen, light and a photosensitizer to produce reactive oxygen species (ROS). Grape seed extract (GSE) and oleanolic acid with known antiviral properties were tested as photosensitizers. Conditions using UV light at 254 nm with a distance of 72 cm and doses (energy density) of 0.012±0.000, 0.020±0.001, 0.040±0.001, 0.061±0.002, 0.081±0.002 and 0.121±0.003 J/cm² for 3, 5, 10, 15, 20 and 30 min exposure times, respectively were applied for the PDI experiments. However, the acquired viral reductions by GSE and OA mediated PDI were attributed to UV light more than ROS production. Future work may include the use of different light sources for illumination, and the use of UA as a potential photosensitizer compound.

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