Lipid oxidation is one of the leading causes of food quality degradation. Manufacturers typically add antioxidants or purge a product's package of oxygen to inhibit oxidation and the resulting off-flavors. Synthetic antioxidants (e.g. BHT, BHA) and some natural antioxidants (e.g. α-tocopherol) have found widespread use in this application. Unfortunately, the public views synthetic additives in a negative light and the current natural antioxidants have been unable to match the protection afforded by the synthetic antioxidants. The search for underutilized and natural antioxidants has led scientists to investigate many different plant-based extracts for use in food and in the treatment and prevention of disease. The objectives of this research were (1) to use ORAChromatography to identify peanut root extract fractions with high antioxidant capacity, (2) identification of compounds in peanut root extracts using HPLC and mass spectrometry, (3) test for the presence of aflatoxins in the extracts, (4) test peanut root extract in food model system for oxidation reduction capabilities, and (5) Testing peanut root extract's ability to decrease protein oxidation in cell culture. Crude peanut root extracts have high antioxidant activities that do not vary by cultivar. The ORAC activities of the peanut root fractions separated by HPLC with a C18 column varied (600.3 – 6564.4 μM TE/g dry extract), as did the total phenolic contents (23.1 – 79.6 mg GAE/g dry extract). Peanut root fractions had aflatoxins contamination well above the 20 ppb limit. Peanut root extracts and the known antioxidants tested were found to have no significant effect in inhibiting oxidation of peanut paste or HBMEC. Peanut root extracts were not shown to have any positive effects, but further research is necessary to eliminate peanut root extracts as a possible food ingredient and health supplement. / Ph. D.