The objective of this study is to determine optimum operating conditions for maximum extraction of oil from subcritical methanol extraction of Chlorella pyrenoidosa. A statistical approach, i.e. response surface methodology (RSM) is employed in this study. The effects of three operational factors: reaction temperature (140 to 220 °C), reaction time (1 to 15 min) and methanol to algae ratio (1 to 9 wt.%) were investigated. A maximum oil yield of 7.1 wt.% was obtained at 160 °C, 3 min reaction time and 7 wt.% methanol to algae ratio. The analysis of variance (ANOVA) revealed that methanol to algae ratio is the most significant factor for maximizing oil yield. Regression analysis showed a good fit of the experimental data to the second order polynomial model.
