Comparison of Oil Soluble Green Tea Extract with Common Antioxidantive Ingredients in Bulk Oil under Different Storage Conditions

Abstract The antioxidant capability of oil‐soluble green tea extract (OSGT) in canola oil was compared to common synthetic and plant‐derived ingredients with antioxidant function. Three storage conditions were included—22–25 °C ambient, 60 °C heated and air‐purging at 22–25 °C. The oxidation process was monitored by electron spin resonance spectroscopy for free radicals, peroxide value for primary oxidative byproducts, proton nuclear magnetic resonance for the loss of oxidatively labile protons, aldehydes as secondary oxidative byproducts and antioxidants residues. Except for tocopherols, the use of antioxidant ingredients improved the stability of the oils under all conditions. However, the extent of improvement differed under different storages for the same ingredients. Evaluating antioxidant ingredients and interpretation of data when using accelerated conditions need caution. Antioxidant level change under different storage conditions provide new insights on the mechanism working of antioxidants in bulk oil. OSGT has comparable performance to TBHQ under ambient temperature conditions. In conclusion, evaluating antioxidant ingredients under accelerated conditions needs caution. Oil‐soluble green tea extract has comparable antioxidative performance to TBHQ in bulk vegetable oil systems without affecting organoleptic properties of the oils under ambient temperature regardless of temperature or oxygen levels.