The objective of the study was to determine the oxidative stability of jatropha oil which is the measurement of the oil’s ability to withstand natural degradation. The factors that affect the oxidative stability of jatropha oil were evaluated using refined jatropha oil. These include the effect of heating, moisture, un-saturation and free fatty acid content. Levels of moisture content, acid value, and the iodine value were determined. In addition, biofuel chemical additives such as IRGASTAB BD 100 and food/oil antioxidant tertiary-butylhydroquinone (TBHQ) were used to investigate ways of retarding the oxidation process in Jatropha Oil. Wijs titration method was used to determine the iodine value while titration with sodium hydroxide was used to determine the acid value (isopropyl alcohol used before titration). The moisture content was found to be 0.22 %. The iodine and acid values increased after heating but decreased significantly after adding the additives. The IRGASTAB BD 100 had the best results in lowering both the acid and iodine values.

The study concludes that under normal conditions of temperature, moisture and oxygen levels, the jatropha oil will remain stable. If subjected to high temperatures in the presence of moisture and oxygen for prolonged period of time, degradation will take place.

It was also predicted that the increase in iodine value after heating may be due to the formation of trans-4-hydroxy-2-nonenal (HNE), a compound that contains double bonds formed by unsaturated vegetable oils when heated at frying temperatures.

Source: Research Unit, Kimminic Corporation, Dr. R. Kahama