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.

Oxidation limits the shelf life of many food products. Adding antioxidants to foods is the most common way to solve this problem. Reports on safety issues of synthetic food additives have raised consumer interest in "all natural" foods, without added antioxidants or with synthetic replaced with natural antioxidants. The natural antioxidants now in use are much more expensive and less potent than the synthetic antioxidants. Thus, effective and economical natural antioxidants are of great interest to researchers. Teng Cha is a type of herbal tea found in China that has reported high levels of antioxidants. Antioxidant activity of Teng Cha extract and its major component dihydromyricetin has been reported, but no studies have provided clear evidence for the antioxidant effectiveness of Tech Cha extracts. The goal of this study was to measure the antioxidant activity of Teng Cha extract and dihydromyricetin (DHM), a major component of Tech Cha extract. The DPPH assay was conducted and antioxidant activities of the crude extract and dihydromyricetin were evaluated in soybean oil based on the peroxide value, anisidine value, Totox value, headspace volatiles and headspace oxygen. Antioxidant effectiveness was also evaluated in a cooked beef model system. DHM was more potent than BHA in preventing soybean oil oxidation. The crude extract was not as effective as BHA and DHM, possibly because it contained transition metals. In cooked beef, DHM and the crude extract showed lower activity than BHA, possibly due to their low solubility. Overall, Teng Cha extract and DHM are potential natural food antioxidants for future applications. / Master of Science in Life Sciences