EFFECTS OF FREE FATTY ACIDS (FFAS) ON THE QUALITY OF Euphorbia tirucalli (L.) OIL EXTRACTED FROM DIFFERENT STEM DIAMETERS IN DIFFERENT AGRO-ECOLOGICAL ZONES OF TANZANIA

Plant oils having lower levels of percent Free Fatty Acids (%FFAs) moieties offer particular potentials in evaluation of qualities of liquid biofuels, because they are associated with reduction of atmospheric pollution relative to petroleum diesel fuel. The present study examined effects of FFAs on the quality of Euphorbia tirucalli (L.) oil extracted from different stem diameters such as 20cm, 30cm, 40cm, 50cm, 60cm, 70cm and 80cm. Soxhlet extraction method was used in oil extraction. Acid Values (AVs) were determined by standard methods ASTM D 664 and the Cd 3d-63 of the American Society for Testing and Materials and the American Oil Chemists Society respectively. The AVs so obtained were used to calculate the amount of FFA contents in E. tirucalli oil as percent oleic acid. One-way ANOVA with the Minitab software v.16 was used to test for differences in %FFAs. The %FFA contents of the oil were compared with the international quality biofuel standard ASTM D 6751 (0.020max). Results showed that the quality of oil which was expressed in terms of %FFAs of oil ranged from 4.57 + 0.02 at 20cm to 4.72 + 0.02 at 40cm, 3.61 + 0.10 at 40cm to 4.42 + 0.10 at 30cm and 2.45 + 0.07at 30cm to 3.06 + 0.07 at 60cm stem diameters from Dodoma, Mbeya and Dar es Salaam agro-ecological zones in the same order. These results indicated low quality of oil since the entire %FFAs were above 0.020max%, not complying with the ASTM D 6751 standard. Also the obtained %FFAs of oils differed significantly (P ≤ 0.05) among different stem diameters and agro-ecological zones. The study concluded that the quality of oil (%FFAs) was low and found to decrease from low to high stem diameters of E. tirucalli in different agro-ecological zones.