Effect of extraction parameters on curcumin yield from turmeric.

Effect of 4 independent variables - temperature (50-90°C), particle size (0.42-0.85 mm), mixing time (10-50 min) and solvent (ethanol) to meal ratio (10-50) on curcumin yield from turmeric (Curcuma longa L) was studied using central composite rotatable design. The experimental value of curcumin yield ranged between 4.49 and 12.89%. The second order model obtained for curcumin yield revealed a coefficient of determination (R(2)) of 0.78 and standard error of 0.72. The linear, square and interaction terms were significant at p <0.05 while lack of fit was non-significant at p >0.05. Surface graphs were plotted to optimize the curcumin extraction. The maximum curcumin yield was obtained when temperature, particle size, mixing time and solvent to meal ratio were 60°C, 0.42 mm, 30 min and 50, respectively.