Natural red pigment production by monascus purpureus in submerged fermentation systems using a food industry waste: Brewer's spent grain

Abstract

This paper studies the production of natural red pigments by Monascus purpureus CMU001 in the submerged fermentation system using a brewery waste hydrolysate, brewer's spent grain (BSG). The chemical, structural and elemental characterization of the BSG was performed with Van-Soest method, Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The lignocellulosic structure of BSG was hydrolyzed with a dilute sulfuric acid solution (2% (w/v)) followed by detoxification with Ca(OH)2. Maximum red pigment production (22.25 UA500) was achieved with the following conditions: 350 rpm shake speed, 50 mL fermentation volume, initial pH of 6.5, inoculation ratio of 2% (v/v), and monosodium glutamate (MSG) as the most effective nitrogen source. Plackett-Burman design was used to assess the significance of the fermentation medium components, and MSG and ZnSO47H2O were found to be the significant medium variables. This study is the first study showing the compatibility of BSG hydrolysate to red pigment production by Monascus purpureus in a submerged fermentation system.