Antioxidant properties of ascorbic acid in bulk oils at different relative humidity

The effects of relative humidity (RH) on the antioxidant properties of ascorbic acid (10, 20, 42, and 84 ppm) were investigated in stripped corn oils stored at 60 °C. The degree of oxidation in oils was determined by analysing headspace oxygen content and conjugated dienoic acids. The oxidative stability of bulk oils without addition of ascorbic acid was significantly different depending on the RH. As the concentration of ascorbic acid increased from 10 to 84 ppm, oxidative stability increased significantly irrespective of RH (p < 0.05). Generally, oils containing ascorbic acid at low RH had higher oxidative stability after storage at 60 °C than those at high RH. The antioxidant properties of ascorbic acid were greatly influenced by both the moisture content in the oil and the ascorbic acid concentration.