Optimization of Pigment-producing Condition in Solid Fermentation of Monascus

The solid fermentation conditions of red yeast for pigment production were optimized by using the response surface optimization method in which fructose additive amount, ammonium chloride amount and initial water contents as independent variables and total pigment value as response ones. The results showed that the optimal medium conditions were with 0.54% fructose, 0.06% ammonium chloride, and 46.00% initial water content. The predicted maximum pigment content in this design was 6 693.99 U·g^-1. Repeated verification tests were conducted, and the actual pigment production reached 6 684.16 U·g^-1, which was with little difference with the predicted maximum pigment output in the model, indicating that the model was well-designed with a high degree of coincidence.