Extraction of radish seed oil ( Raphanus sativus L .) and evaluation of its potential in biodiesel production

Growing concern about replacing fossil fuels with renewable energy sources, coupled with society’s concerns about environmental preservation, are the main reasons why governments have sought strategies for increased production and consumption of renewable and sustainable fuels. Radish (Raphanus sativus L.) belongs to the group of oilseeds of the Brassicaceae family, being widely cultivated in the south and central-west regions of Brazil, with physical and chemical characteristics propitious to the production of biofuels. In this context, the objective of the present work was to evaluate three different methods of oil extraction: solvent extraction, cold pressing and swelling technique, to evaluate the potential of radish oil in biodiesel production using methanol, ethanol and a mixture of both containing 60% and 40% respectively, and to evaluate the composition of fatty acids. The methodology consists firstly in the extraction of the oil, followed by transesterification reaction using 10 mL of pretreated oil and sodium hydroxide in the proportion of 1% in mass, relative to the oil. The oil samples were used in the transesterification reactions with methanol, ethanol and a mixture of methanol (60%) and ethanol (40%) in different proportions and temperatures. The results indicated that, for the oil extraction processes, the seed swelling technique presented a high extraction yield (34%). The composition of fatty acids showed presence of approximately 30% of saturated compounds and around 50% of compounds with chain up to 18 carbons, also had presence of erucic acid (up to 41%), and a high percentage of oleic acid (up to 30%). Regarding the transesterification reactions, the highest yield occurred with the use of methanol, about 86%. Thus, in the light of the results, it can be concluded that radish oil has great potential for biodiesel production, but, other analyzes, such as acidity and flash point, should be performed to more specifically evaluate the physicochemical characteristics of biodiesel.