English
Optimization of Monascus ruber Fermentation: Liquid Culture Conditions and Solid-State Fermentation Using Garumi
Suyeon Gu, Jun-tae Kim, Eunbi Oh, Seungwha Jo and Sung-ho Cho*
Microbial Institute for Fermentation Industry
*Email: sunghyej3@nate.com
To optimize red yeast rice (RYR) fermentation using Monascus ruber, both liquid- and solid-state fermentation processes were evaluated. Garumi and polished rice were first compared as fermentation substrates. Garumi showed superior performance, with the highest monacolin K content (586.55 mg/kg) on day 15 and no citrinin detected, whereas citrinin was present in polished rice. Accordingly, Garumi was selected for solid-state fermentation. For liquid-state fermentation, aimed at optimizing M. ruber growth and pigment production, a Box-Behnken Design (BBD)-based response surface methodology (RSM) was applied using glucose, defatted soy flour, and MSG as variables. The optimal conditions were predicted to be 21.07 g/L glucose, 14.97 g/L defatted soy flour, and 0.03 g/L MSG. Solid-state fermentation was then optimized using Garumi as the substrate. Incubation temperature (25, 30, and 35°C) and initial moisture content (30%, 40%, and 50%) were tested over a 15-day fermentation period. All conditions showed increasing pigment and monacolin K production over time, with no citrinin detected. The condition of 30°C and 50% moisture yielded the highest color value (341.40 U/g) and monacolin K content (792.99 mg/kg) on day 15. These results provide valuable insight into the culture condition optimization of M. ruber and confirm Garumi as an effective substrate for safe and functional red yeast rice fermentation.
