Antioxidant activity of deodorizer distillate fractions in rapeseed oil

Abstract

Fractions of rapeseed oil deodorizer distillate containing vinylsyringol and its dimer, which are degradation products of sinapic acid, and other phenolic compounds were investigated for their potential use as antioxidants in refined rapeseed oil. Vinylsysringol, vinylsyringol dimer (VSD), and sinapic acid could effectively inhibit the formation of hydroperoxides, propanal, and hexanal in rapeseed oil triglycerides during storage at 40°C in the dark and at 25°C under light. In the presence of tocopherol, the addition of VSD increased the oxidative stability considerably at low tocopherol concentrations (25 μM) and if the VSD concentration was 10–20 times as high as the tocopherol concentration. The addition of polyphenolic rich fractions of the deodorizer distillate to commercial rapeseed oil resulted in slightly accelerated lipid oxidation in the dark at 40°C but did not influence the formation of hydroperoxides under light at 25°C. Practical applications: This study does not give any implications to change the process conditions during refining in a way that VSD would be removed from the oil. On the other hand, the fractions could be added for their positive health effects or as flavouring in savory products without jeopardizing the storage stability of the oil. Fractions of rapeseed oil deodorizer distillate rich in phenolic compounds were investigated for their potential use as antioxidants in rapeseed oil. The isolated compounds effectively inhibited lipid oxidation in the dark and under light. In the presence of tocopherol, the addition of the dimer increased the oxidative stability considerably at low tocopherol and high vinly syringol dimer concentrations. The addition of polyphenolic rich fractions of the deodorizer distillate to commercial rapeseed oil resulted in slightly accelerated lipid oxidation in the dark at 40°C but did not influence the formation of hydroperoxides under light at 25°C.