Statistical Modelling of Oil Expression from Neem Seed using a Screw Press
A study was carried out to determine the effect of some process parameters on the yield of neem seed oil from a screw press using 44 factorial design experiments. This consisted of four independent, randomly assigned parameters at four levels each namely, moisture content (wb) of seeds (6.3%; 8.1%, 13.2% and 16.6%); temperature of heating at ϴ1 (55°C), ϴ2 (70°C), ϴ3(85°C) and ϴ4 (100°C); duration of heating at t1 (5 min.), t2(10 min.), t3 (15 min.) and t4 (20 min.) and machine pressure at p1 (602.91 kN/m2), p2 (723.07 kN/m2), p3(925.84 kN/m2) and p4(1334.88 kN/m2). Three replicates of the experiments were carried out and from the values obtained, oil yield was calculated. The effects of the processing conditions (moisture content, heating duration, heating temperature and machine pressure) on the oil yield were investigated using analysis of variance (ANOVA) at p≤0.05 and the levels of the significant means were further evaluated using Duncan’s New Multiple Range Test (DNMRT). Mathematical model was developed to express the oil yield with respect to the process parametersand this was fitted to experimental data using MATLAB 8.0 software package. Adequacy of the model was authenticated using coefficient of determinationand adjusted coefficient of determination, R2.The results obtained showed that temperature, heating time, moisture content, pressure and their interactions all proved to determine the outcome of oil yield of neem seed. The highest oil yield of 33.55% was obtained at temperature of 81.98°C, pressure of 1067.23kN/m2, moisture content of 9.03% and heating duration of about 20 min.Theresults obtained(coefficient of determination and adjusted coefficient of determination R2) indicated that the model generated was statistically adequate.