Process optimization and characterization of manila tamarind seed oil extracted by the soxhlet method

This work mainly presents an experimental investigation of the extraction of oil from Manila tamarind seeds (Pithecellobium dulce (Roxb.) Benth) using a Soxhlet-assisted solvent extraction method. Different factors that affect the extraction of oil were analyzed and optimized using the response surface methodology (RSM). Three process variables, namely, solvent volume, extraction time, and powder weight, were adopted in a three level Box-Behnken design. Based on the experimental design, 17 experimental runs were performed to evaluate the effect of selected variables on the oil yield. A polynomial model is suggested and found to be significant. From the results of analysis of variance (ANOVA), it is found that the powder weight and solvent volume significantly affect the yield of the produced oil. The results showed that the oil yield could be maximized under the optimized conditions of powder weight, solvent volume, and extraction time of 40 g s, 314 mL, and 6 h, respectively. The physicochemical properties of extracted oil showed that it is brownish yellow liquid with specific gravity and refractive index of 0.92 and 1.4631, respectively. Similarly, the moisture content, acid value, unsaponifiable matter, iodine value, free fatty acid, saponification value, and peroxide value were found to be 0.12%, 8.32 mg/g KOH of oil, 0.4%, 83.9 g I2/100 g of oil, 4.16 mg/g KOH of oil, 175.4 mg/g KOH of oil, and 6.10 meq O2/kg, respectively. The results also revealed that the presence of stearic fatty and saturated palmitic acids were the major fractions in the Manila tamarind seed oil (MTSO) along with other unsaturated fatty acids.