Analysis and derivatization of castor oils extracted from castor seeds collected from six regions in Tanzania

The oil yields, physico-chemical parameters and the fatty acid profiles of castor oils extracted from seeds collected from different regions in Tanzania were determined. The oil was extracted from castor seeds by Soxhlet method using n-hexane solvent and its physico-chemical analysis was done using standard methods with some minor modifications. The physico-chemical properties were, oil yields (43.69% -52.78 %), refractive index (1.468-1.473), pH(5.7- 6.3), viscosity (0.943 - 0.954), specific gravity (165.50 – 187.46 mg KOH/g Oil), saponification value (76.68- 80.12 g I2/100 g Oil), iodine value(0.44- 1.97 mg NaOH/g Oil), acid value, free fatty acid (0.22- 0.99) and peroxide value (10.79 – 13.73). Castor seeds collected from Dodoma had the highest oil yield of 52.78% while those from Dar es Salaam had the lowest yield of 43.69%. The fatty acid profile of the castor oil was determined from prepared FAME of each sample using GC-MS and ricinoleic acid which was found to range between 83.5% and 92.3 %. A series of oxidation reactions on castor oil was done using Pyridinium chlorochromate (PCC) converting it to ketone (2,3-Bis[[(Z)-12-oxooctadec-9-enoyl]oxy]propyl(E)-12-oxooctadec-9-enoate) and then the ketone to ester (2,3-Bis[[(Z)-11-heptanoyloxyundec-9-enoyl]oxy]propyl(E)-11-heptanoylundec-9-enoate) by m-CPBA (Baeyer Villiger oxidation). The chemical structures of these compounds were elucidated using ATR-FTIR, 1H-NMR and 13C-NMR techniques. This study has produced the first report on the oil yield, fatty acid profile and physicochemical properties of castor oil extracted from castor beans harvested from six regions of Tanzania.