Effects of glutamic acid (Glu) and monosodium glutamate (MSG) on oxidative stability of oil-in-water (O/W) emulsions with different emulsifier charges during riboflavin (RF) photosensitization were evaluated by analyzing headspace oxygen content and conjugated dienes. Cetyltrimethylammonium bromide (CTAB), Tween 20, and sodium dodecyl sulfate (SDS) were used as cationic, neutral, and anionic emulsifiers, respectively. Glu acted as an antioxidant in CTAB- and Tween-20-stabilized O/W emulsions during RF sensitization, whereas Glu acted as prooxidants in SDS-stabilized O/W emulsions in the dark. However, adding MSG did not have a constant impact on the degree of oxidation in O/W emulsions irrespective of the emulsifier charge. In RF-photosensitized O/W emulsions, the emulsifier charge had a greater influence on antioxidant properties of Glu than on those of MSG.

Introduction
Materials and Methods
    1. Materials
    2. Sample Preparation for the Emulsion and Photosensitization
    3. Zeta Potential and Droplet Size Analysis
    4. Headspace Oxygen Analysis
    5. Analysis of Conjugated Dienes
    6. Statistical Analysis
Results and Discussion
    1. Effects of Glutamic Acid on the Oxidative Stability ofO/W Emulsions
    2. Effect of Addition of Monosodium Glutamate on theOxidative Stability of O/W Emulsions
    3. Zeta Potential and Droplet Size Analysis of O/WEmulsions Containing Glu or MSG
Conclusions
Acknowledgment
References

• Ji-Yun Bae(Graduate Student, Dept. of Food and Nutrition, Kangwon National University, Samcheok 25949, Korea)
• Mi-Ja Kim(Associate Professor, Dept. of Food and Nutrition, Kangwon National University, Samcheok 25949, Korea) Corresponding author