Inhibition of Ascorbic Acid Photooxidation in Beverage Model System by Rice Bran Oil Nanoemulsion Containing γ–Oryzanol

Photooxidation is one of the oxidation in food and beverage. To inhibit photooxidation, the singlet oxygen quencher is needed. Since many antioxidants are lipophilic, they should be delivered by lipid-based delivery systems, i.e., nanoemulsion. γ–Oryzanol is a well-known antioxidant naturally found in rice bran oil. This study aimed to evaluate the capability of rice bran oil nanoemulsion against ascorbic acid photooxidation in the beverage. The ingredients in nanoemulsions were rice bran oil,
virgin coconut oil, palm oil, Tween 80, and distilled water. Low-energy methods could fabricate nanoemulsion via emulsion phase inversion. The formula nanoemulsion could be stable for up to 30 minutes of heating in an oven at 105 °C by turbidity parameter. During storage at both 28 and 37 °C,
nanoemulsions could also be stable for up to 28 days in the dark. They had narrow particle distributions (<0.15) and nano-sizes (<200 nm). Phototoxidation by singlet oxygen could induce ascorbic acid degradation. The best formulas were 6A and 7A. Adding 1 and 5% of nanoemulsions could retain ascorbic acid during a photooxidation test for up to 2 hours. The initial concentration of ascorbic acid in the beverage product, packaging, and storage place should be considered for future applications.