Effects of Temperature and UV Light on Degradation of [alpha]-Tocopherol in Free and Dissolved Form

• Published in: Journal of the American Oil Chemists' Society 2009-09, Vol.86 (9), p.895
• Main Authors: Sabliov, Cristina M, Fronczek, C, Astete, C E, Khachaturyan, M, Khachatryan, L, Leonardi, C
• Format: Article
• Language: English
• Subjects: Atmospheric pressure; Chemicals; Degradation; High temperature; Kinetics; Light; Methanol; Nutrition; Olive oil; Studies; Ultraviolet radiation; Vitamin E
• ISSN: 0003-021X; 1558-9331

The effects of heat and UV exposure on the degradation of free α-tocopherol (oil form), α-tocopherol dissolved in methanol, and α-tocopherol dissolved in hexane were measured. Results showed that degradation of free α-tocopherol due to heat followed first order kinetics, with the samples held at 180 °C showing the greatest degradation rate. Free α-tocopherol degraded faster at high temperatures than dissolved α-tocopherol. In contrast, free α-tocopherol did not degrade when exposed to UV light for as long as 6 h, but the hexane and methanol samples degraded significantly as a matter of time. The α-tocopherol dissolved in hexane and methanol degraded by 20 and 70%, respectively over this time span. A mechanism for degradation of α-tocopherol was proposed to explain the higher degradation rate of α-tocopherol in methanol, as compared to hexane for times longer than 180 min. Knowledge of degradation kinetics of pure α-tocopherol as a result of temperature or exposure to UVA light whether in free or dissolved form is critically needed to understand how different processing parameters affect the amount of α-tocopherol during extraction, stabilization, storage or encapsulation processes. [PUBLICATION ABSTRACT]