Optimization of Solvent Extraction of Oil from Neem (Azadirachta indica) and Its Characterizations

Aims: Optimization of neem oil production and its characterization using Response Surface Methodology (RSM) was carried out in this study. The effects of three factors: sample mass, particle size and extraction time on the response, neem oil volume extracted, were investigated
Study Design: The Box-Behnken design of RSM was employed which resulted in 17 experimental runs.
Place and Duration of Study: Department of Food Science and Technology, Federal University of Technology, Akure, Nigeria, between July, 2010 and July, 2011.
Methodology: This was carried out in a 250 ml Soxhlet extractor. The solvent used was Petroleum-ether. The neem seed powder was packed inside a muslin cloth placed in a thimble of the Soxhlet extractor. The extraction was carried out at 60ºC using thermostated heating mantle. The solvent in the extracted oil was evaporated and the resulting oil further dried to constant weight in the oven. The fatty acid profile of the extracted oil were determined using gas chromatograph analysis while the physicochemical properties were determined using Association of Official Analytical Chemists (AOAC) 1990 methods.
Results: Results showed that optimized value of 49 % (47 ml) of neem oil was obtained at 45 g mass of sample, 1.39 mm particle size 2 h extraction time. In addition, neem oil had 0.15 % moisture contents, 0.88 specific gravity, 201.21 mg KOH/g saponification value, iodine value 78 gI2/100 g, acid value 10.21 mg KOH/g, peroxide value 6.80 meqO2/Kg, Cetane number 54.38 and Calorific value 40.01 MJ/Kg. The neem oil showed that the percentage unsaturation was 83.05% while the percentage saturation was 16.95 %. The Analysis of Variance (ANOVA) results of the Response Surface Methodology showed that all the linear coefficients and the quadratic coefficients were significant (p = 0.05). The R2 and R2adj values of 0.9966 and 0.9935 respectively indicated that the regression model was a good one.
Conclusion: Extraction of neem oil has been successfully optimized using RSM. The physicochemical properties and fatty acid profile showed that the oil extracted is suitable for renewable fuel raw material source.