Eugenol and TBHQ antioxidant actions in commercial biodiesel obtained by soybean oil and animal fat

The use of antioxidants in biodiesels, especially the synthetic TBHQ, has been an efficient way of maintaining the oxidative stability of biofuel during storage for a longer period. Considering other types of products, the use of several natural antioxidants, such as Eugenol, has been promising to increase oxidation stability and conservation of foods, with few studies on biodiesel conservation. This study aimed to evaluate the antioxidant action of Eugenol and TBHQ in commercial biodiesel produced from soybean oil and animal fat blend in order to evaluate the efficiency of these antioxidants. Thus, the samples of pure commercial biodiesel (without antioxidant), enriched with the antioxidant TBHQ and Eugenol were prepared and stored in an oven at constant temperature of 43 °C for 150 days. Periodically, the samples were characterized by ultraviolet absorption spectroscopy and oxidation stability (Rancimat method). They were also chemically characterized concerning the acidity, peroxide and iodine amounts. The results showed higher efficiency of the antioxidant Eugenol in relation to the TBHQ, considering that the oxidation stability was within the standard legislations.