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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



Lipid oxidation is one of the major challenges faced by the food industry as it contributes to the loss of nutritional quality and loss of flavor in food products. Studies have shown that naturally occurring phospholipids like phosphatidylserine (PS) and phosphatidylethanolamine (PE) can regenerate oxidized tocopherols and help delay the lipid oxidation in bulk oils and oil-in-water emulsions. Since consumers desire simpler and cleaner labels, without chemically synthesized antioxidants, this research is of great interest. The combination of PS and PE with tocopherols has already been studied. However, PS was a better antioxidant in combination with tocopherols in the oil-in-water emulsion system whereas PE was a better antioxidant in combination with tocopherols in bulk oils. But obtaining pure phospholipids is an expensive deal, therefore, this study uses the more economical alternative, high phosphatidylserine (PS) lecithin in combination with mixed tocopherols in soybean oil-in-water system. PS (30 µmol/kg emulsion) along with mixed tocopherols (3 µmol/kg emulsion) were dissolved in oil and emulsions stabilized by Tween20 were prepared. To determine the most effective concentration of mixed tocopherols, 0.5, 1.0, and 3 µmole of tocopherols/kg emulsion were used at pH of 3 and 7. Tocopherol with a concentration of 3 µmole/kg emulsion was found to be the most effective at pH 3. Tocopherols showed an extended lag phase at lower pH. The synergistic activities of authentic PS and high PS lecithin were compared in combination with tocopherol under similar conditions. They both had an almost similar lag phase. This combination was then tested for different pH of 3 and 7 and different salt concentrations of (0.5, 1, and 1.5 wt% of the emulsion) at pH 7 to determine the effects of external factors on the synergistic antioxidant combination. It was observed that the combination had extended antioxidant ability at lower pH of 3 whereas salt had no effect on the combination. The results showed that high PS lecithin forms a synergistic combination with mixed tocopherols to increase the lag phase in oil-in-water emulsions and can be used as a clean label antioxidant for oil-in-water emulsions.


First Advisor

Eric A Decker