Influence of Synthetic and Natural Antioxidants on the Oxidation Stability of Beef Tallow Before Biodiesel Production

Beef tallow is a promising alternative as a non-edible raw material for biodiesel production, due to its lower price compared to vegetable oils such as soybean oil. The problem of using beef tallow as a raw material for biodiesel is its high acidity level, found as a consequence of hydrolysis and oxidation reactions. These degradation processes are significant in the presence of high levels of humidity and temperature, which are usually found in the storage conditions. In this study, the influence of synthetic and natural antioxidants on the oxidation stability of beef tallow was evaluated using Rancimat tests and by monitoring their acid and peroxide values over 148days of storage in an oven. The studied synthetic and natural (cashew nut shell liquid, CNSL) antioxidants were effective to prevent oxidation of beef tallow on storage conditions. Biodiesel samples were produced from samples of beef tallow with and without antioxidants. The biodiesel samples produced from beef tallow containing BHT presented the best induction period values. The biodiesel samples produced from beef tallow containing technical CNSL (0.5wt%) met the requirement of oxidation stability at 110 degrees C determined by the Brazilian specification.