Biodiesel as an alternative diesel fuel obtained by transesterification of
vegetable fats and oils, using alcohol in the presence of a catalyst, has some
advantages such as reduced emissions of unburned hydrocarbons, carbon
monoxide, sulfates, polycyclic aromatic hydrocarbons, and particular matter,
but its drawback, of being more prone to oxidation than petroleum-based diesel
fuel, can cause the fuel to become acidic (cause fuel system corrosion) and
to form insoluble gums and sediments and consequently increase its viscosity.
In this study, in order to increase the stability of biodiesel based on high oleic
acid sunflower oil against oxidation process during the storage and distribution,
different percents [0.01%, 0.02%, 0.05%, 0.1%, and 0.2% (w/v)] of maize
flour contaminated by mycotoxins, thus useless for human consumption, were
added as natural antioxidants. The antioxidant effect increased with concentration
up to an optimal level. Above the optimal level, the increase in antioxidant
effect with its concentration was relatively small. Oxidative stability of biodiesel
was determined using two parallel methods, the Schaal oven storage test (at
70°C) and the Rancimat method (at 110°C). The induction times obtained by
the Rancimat method were more similar to the values determined by the oven
test. The highest protective effect was observed in samples containing 0.1% (w/
v) of added antioxidants.
