Influence of Seed Variety and Extraction Technique on Fatty Acid Distribution and Quality Parameters of Tropical Castor (Ricinus communis L.) Oils

Industrial application of castor oil is anchored on both agronomical and technological variables that intrinsically influence its quality properties. Therefore, castor oils of two varieties (Gibsoni and Carmenicita), extracted by screw press, solvent and traditional methods were compared in terms of oxidative stability indices, quality parameters and fatty acid distributions. General factorial analyses showed the significance of both factors on the oil yield, color intensity, moisture content, oxidative stability indices, most of the oil’s fatty acids and other quality parameters. Gibsoni variety yielded more oil at the range of 40.12 – 53.51%, especially in solvent extraction. The two oxidative stability indicators; peroxide value (PeV) and free fatty acids (FFA) favored traditional extraction and were significantly higher in oils of Carmenicita variety, at 4.26 – 7.21 meqO2/kg and 2.55 – 3.94%, respectively. In addition to ricinoleic acid (85.93 – 89.19%), other fatty acids characterized in the oils include, oleic (4.73 – 5.84%), stearic (1.41 – 2.50%), linoleic (1.08 – 3.41%), and palmitic acids (0.60 – 1.29%). Saponification (SaV) and iodine values (IoV) of the oils were unaffected by varietal differences or extraction processes and the ranges recorded in both varieties were within ASTM (175 – 187 mgKOH/g) and EN 14214 (120–140 g I2/100 g) acceptable limits. Principal component analysis (PCA) model built on the data of the oils further emphasized the significance of these two factors in quality characterization of castor oil.