Improving the Production and CIELAB* Color Parameters of Monascus ruber Pigments using a Fractional Factorial Design

ruber Van Tiegham using submerged culture technique. The fermentationmedia contained rice flour, peptone, glycerin, glucose, MgSO4, KNO3 and thevariables studied included the addition of zinc, ammonium and glutamate inthe liquid culture. The experiments were designed to investigate theproduction of pigments using a Box Behnken design. The influence of each ofthese factors on pigment production were evaluated by the ratio of 500 nmand 400 nm absorbance measurements and by the color parameters of theCommission Internationale d'Eclairage L*A*B* system. Total and redpigments measured as absorbance units showed optical density values ashigh as 21.78 and 11.67 absorbance units, respectively, which was close tovalues reported in the literature for solid-state culture. The response surfaceanalysis proved a quadratic effect of zinc concentration on both pigmentproduction and color quality. This result is quite important because thequadratic effect of zinc was not reported before in the literature and itdemonstrates there is an optimum concentration of zinc for pigmentproduction and quality. More importantly, color L*A*B* measurementsshowed that the increase in total red pigment production caused noprejudice in color quality within the range of the experimental conditions.The results demonstrate the feasibility of pigment production with high colorquality in submerged culture.