Production and evaluation of biodiesel from sweet orange (Citrus sinensis) lipids extracted from waste seeds from the commercial orange juicing process

The citrus industry generates a significant amount of excess biomass when producing juices for human consumption. This underutilized biomass causes environmental issues when discarded, so finding uses for this material reduces waste while potentially generating new revenue streams. Oil (37 wt%) extracted from inedible sweet orange (Citrus sinensis) seeds obtained as waste from the commercial orange juicing process was investigated as a feedstock for production of biodiesel. Fatty acid methyl esters were prepared by sodium methoxidecatalyzed transesterification of sweet orange seed oil. The principal fatty acids identified in the oil were linoleic (33.9 %), palmitic (27.8 %), and oleic (27.1 %) acids. Fuel properties of the resulting biodiesel were compared to ASTM D6751 and EN 14214. The cloud and pour points were 8.7 and 7.9 degrees C, respectively, and the oxidative stability (110 degrees C) was 0.7 h. Overall, the methyl esters were within the specifications of the biodiesel standards, except for oxidative stability.