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Production and optimization of monacolin K by citrinin-free Monascus pilosus MS-1 in solid-state fermentation using non-glutinous rice and soybean flours as substrate
- Feng, Yanli, Shao, Yanchun, Zhou, Youxiang, Chen, Fusheng
- European food research & technology 2014 v.239 no.4 pp. 629-636
- Monascus pilosus, acetic acid, blood serum, cholesterol, citrinin, cooling, dietary supplements, inoculum, lovastatin, magnesium sulfate, rice, rice flour, solid state fermentation, soy flour, statistical analysis, triacylglycerols, water content
- Monacolin K (MK) acts as a natural inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase. Red fermented rice by Monascus spp. which is rich in MK can be used as dietary supplement to reduce the serum triglyceride and total cholesterol. A Monascus pilosus MS-1 with high-producing MK but free of citrinin had been screened in our previous investigation. Here, its solid-state fermentation parameters were optimized using statistical methods to maximize MK yield when non-glutinous rice and soybean flours were used as substrate. Maximum MK yield (17.662 mg/g) was predicted when 55 g dry substrate (20 sieve mesh), including 60 % non-glutinous rice flour and 40 % soybean flour, was put into a 250-mL conical flask, and the contents of water, acetic acid and MgSO₄·7H₂O were adjusted to 35 %, 0.6 % (v/w) and 0.004 mol/kg, respectively. Then, the substrate was mixed and sterilized, and scattered before cooling. Later, 13 % (v/w) inoculum pre-cultured for 36 h at 30 °C was used, then incubated at 30 °C for 60 h and followed by a further incubation at 24 °C up to 14 days. The verified MK yield was 18.733 mg/g, which was 106.06 % to the predicted MK yield. The MK yield was enhanced to 33 times after optimization. No citrinin was detected in Monascus pilosus MS-1 fermented products. These results indicate that citrinin-free MK can be produced under the optimized conditions.