Oxidative Stability in Oil‐in‐Water Emulsions with Quercetin or Rutin Under Iron Catalysis or Riboflavin Photosensitization

The effects of quercetin and rutin on the oxidative stability of oil‐in‐water (O/W) emulsions were tested under riboflavin (RF) photosensitization in the presence or absence of FeCl2. The degree of oxidation in O/W emulsions was determined by headspace oxygen content, conjugated dienes, and lipid hydroperoxides. Quercetin chelated more metal than did rutin in iron catalyzed O/W emulsions. Generally, 0.1 mM quercetin and rutin was oxidative while 0.5 and 1.0 mM quercetin and rutin was antioxidative in O/W emulsions under RF photosensitization. Depending on the analysis method, the antioxidants had different strengths. The antioxidative or oxidative properties of quercetin and rutin vary in O/W emulsions and depend the quercetin and rutin concentrations and oxidative forces like transition metals, RF photosensitization, or a combination thereof. Using phytochemicals with natural origins is a practical strategy to control rates of lipid oxidation. In this study, the antioxidant properties of quercetin and rutin were evaluated in O/W emulsions under metal catalysis and riboflavin photosensitization. Generally, quercetin was more antioxidative than was rutin. To achieve antioxidant properties, the quercetin concentration should be higher than that of transition metals. The results of this study can help extend the shelf life of O/W emulsion foods containing quercetin and rutin under light irradiation or in the presence of iron.