Date of Award


Document Type


Degree Name

Master of Science (MS)


College of Education and Human Services


Nutrition and Food Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Charles Feldman

Committee Member

Shahla Wunderlich

Committee Member

Lee Lee


As time has progressed, companies have increasingly produced foods for longer term storage. This has led to an increased use of food preservatives in processed foods. People have now come to expect many foods to have a significantly longer shelf life, and this is a matter of government concern for public health due to foodborne contaminations. Foodborne illnesses have become a common problem caused by bacteria (i.e. Escherichia coli). Finding an effective natural preservative source might be better received by the public and alleviate some health concerns over chemical sources. The most important active ingredient found in green tea is camellia sinensis. Epigallo-cathechin-3-gallate (EGCG) is the primary active polyphenol in camellia sinensis. Palmitoyl-epigallocatechin-3-gallate (P-EGCG), and epigallocatechin-3-gallate-stearate (EGCG-S) are two modified tea polyphenols which were studied in the current experiments. Green tea extracts contain antioxidant, antimicrobial, antimutagenic, and anticarcinogenic properties. In this study, the stability of EGCG, P-EGCG and EGCG-S were determined by the incubation rates of Escherichia coli; Lactobacillus bacillus; and Streptococcus thermophiles. The green tea polyphenols’ antimicrobial properties were evaluated at different temperature and pH conditions. The temperatures used in the current studies were: 27 °C (room temperature); 37°C, 55°C, and 68°C (three pasteurized conditions: 68°C water bath 24h, 30min 68°C water bath before 24h 27°C treating, 30min 68°C water bath after 24h 27°C treating). The nutrient broth (pH=7.0) and clementine orange juice (pH=3.03) were used to determine the stability of EGCG, P-EGCG and EGCG-S. The stable effect of EGCG, P-EGCG and EGCG-S were analyzed through Colony Forming Units (CFU). The next objective of this study was to determine the antioxidant effect of EGCG, P-EGCG and EGCG-S with clementine orange juice through the UV-spectrometer. According to the data analysis, it suggests that P-EGCG is the most effective tea polyphenol in reducing bacteria growth and maintaining antioxidant properties of clementine orange juice during storage. Therefore, P-EGCG could be considered as having the best potential among the tested polyphenols as a citrus juice preservative.