Assessing the Impact of Heat on alpha-tocopherol Content in Cold – Pressed Groundnut Oil

Background: Vitamin E is a vital nutrient with strong antioxidant properties that plays an important role in maintaining various functions in the human body. Cooking processes such as frying, baking, and boiling can lead to the loss of alpha-tocopherol, significantly reducing its bioavailability in food products. The aim of the current study was to ascertain the actual alpha-tocopherol content in groundnut oil and evaluate its stability after heating to cooking temperature. Methods: The wavelength maxima of alpha-tocopherol were evaluated using UV-Visible spectroscopy, and the oil sample was saponified and analyzed for alpha-tocopherol content. A method was developed for the extraction and quantification of alpha-tocopherol using UV-Visible spectroscopy. The oil sample was subjected to 100, 150, and 200°C and quantified for alpha-tocopherol content using the developed method. Results: The absorption maximum (λmax) of alpha-tocopherol was 284.5 nm and obeyed the Beer-Lambert law. The calibration curve showed linearity between 50 and 350 µg/ml, and the limit of detection (LOD) and limit of quantification (LOQ) were found to be 8.24 µg/ml and 25 µg/ml, respectively. The method was validated according to ICH standards, and the percent recovery was 99–100% with a standard deviation (SD) of less than 1%. As the cooking temperature increased, the concentration of alpha-tocopherol declined, starting from 738.27 ± 9.26 µg/ml at 100°C, dropping to 680.67 ± 14.76 µg/ml at 150°C, and reaching 585.95 ± 16.30 µg/ml at 200°C. One-way analysis of variance (ANOVA) was performed using IBM SPSS Statistics version 22.0, which demonstrated a statistically significant difference between the groups. Conclusion: This study unequivocally establishes alpha-tocopherol as highly heat-sensitive, with degradation exacerbated by prolonged exposure to elevated cooking temperatures. A significant drop in the concentration of alpha-tocopherol at 100°C indicates early oxidative degradation, and more than 50% loss was noted at 200°C.