Author(s): Cristiane Cardoso Correia Teixeira, Guilherme Augusto Teixeira, Luis Alexandre Pedro Freitas
The aim of this work was to study the production of pigments by Monascus ruber Van Tiegham using submerged culture technique. The fermentation media contained rice flour, peptone, glycerin, glucose, MgSO4, KNO3 and the variables studied included the addition of zinc, ammonium and glutamate in the liquid culture. The experiments were designed to investigate the production of pigments using a Box Behnken design. The influence of each of these factors on pigment production were evaluated by the ratio of 500 nm and 400 nm absorbance measurements and by the color parameters of the Commission Internationale d'Eclairage L*A*B* system. Total and red pigments measured as absorbance units showed optical density values as high as 21.78 and 11.67 absorbance units, respectively, which was close to values reported in the literature for solid-state culture. The response surface analysis proved a quadratic effect of zinc concentration on both pigment production and color quality. This result is quite important because the quadratic effect of zinc was not reported before in the literature and it demonstrates there is an optimum concentration of zinc for pigment production and quality. More importantly, color L*A*B* measurements showed that the increase in total red pigment production caused no prejudice in color quality within the range of the experimental conditions. The results demonstrate the feasibility of pigment production with high color quality in submerged culture.