Quantitative and qualitative assessment on the suitability of seed oil from water plant (Trichilia emetica) for soap making

Despite widespread and its local available as a naturalized hedge and shade plant, the potential of Trichilia emetica was not utilized in soap making by the majority of local community in various parts of Dodoma, Tanzania. This study aimed to assess the quantity (yields) and quality (Acid Values (AVs), %Free Fatty Acids (%FFAs) and Saponification Values (SVs) of seed oil from water plant (T. emetica), suitable for soap making application. Solvent extraction method was used during oil extraction, where by 50gm of preheated and powdered seed materials were immersed in 250 ml of n-hexane in 1:5 (w/v) to dissolve the oil contained in the seed cake. The oil was collected by vaporizing solvent out through Rotary evaporation at 60 °C. Also standard titration methods were used to obtain SVs, AVs and %FFAs of the extracted oil. Results showed that T. emetica seeds contained higher quantity of oil (48.4%−50.2%) than many reported commercial plant seed oils. Also, the study found higher AV (7.4 mgKOH/g−7.8 mgKOH/g), %FFA (3.7% to 3.9%) and SVs (189.5 mgKOH/g − 191.4 mgKOH/g) than the maximum acceptable limits of 0.50 mg KOH/g, 0.020% and 175 mgKOH/g − 187 mgKOH/g prescribed by ASTM standards (2002). The obtained results showed that, T. emetica seeds yielded high oil quantity with low qualities due to higher levels of acidity. But high SVs guarantees the possibility of using T. emetica seed oil in soap making. However, the oil requires purification in order to bring levels of acidity to acceptable standards and guarantee its normal use in soap making.