Effects of Temperature and UV Light on Degradation of α‐Tocopherol in Free and Dissolved Form

Abstract

Abstract 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.