Solid-state fermentation for the production of Monascus pigments from soybean meals

Abstract

The aim of the present study was to investigate feasibility of soybean meal powder as a nitrogen substrate for the production of pigments by Monascus purpureus ATCC 16362 in solid-state fermentation using soybean meals as nitrogen sources to replace yeast extracts. Central composite design was used to assess the optimum level of soybean meal replacement (0–100%), ZnSO4.7H2O concentration (0–0.02 g/L) and thermal stress time of spore suspension at 70°C (50–90 s). Red Monascus pigment and biomass productions were assessed as dependent responses. A pigment yield of 7.06 AU/g dry fermented substrate was achieved using soybean meal powder with optimized process parameters such as a 50% initial moisture content and incubation at 30 °C for 21 days. Addition of Triton X-100 to solid-state fermentation media significantly increased red Monascus pigments (p < 0.05). Stability of the red Monascus pigments was assessed under storage time (90 days). At high temperatures of storage, degradation constant of the red pigments increased in the presence of light during the shelf-life. This study recommends use of Monascus purpureus for the efficient production of red pigments using low-cost substrates in solid-state fermentation by food industries.