Dynamic changes of active substances of rice, Pueraria and yam fermentation by Monascus ruber

Monascus spp., a fungus of medicine food homology, produces various beneficial secondary metabolites such as monacolin K (MK) during fermentation. In this study, the mixed fermentation of Monascus with rice, Pueraria, and yam has been systematically investigated. Single-factor and response surface methodology (RSM) were carried out to maximize MK content, and the optimized fermentation results showed that the content of MK reached 1.40 ± 0.04 mg/g. The optimal fermentation process determined the ratio of 8: 1: 1 for rice, Pueraria, and yam, respectively, the inoculation amount was 106 spores/mL, fermentation time was 15 days. Further analysis of the content of active substance in the fermentation process revealed that the β-glycosidase activity increased, the amylase enzyme activity decreased, the dioscin content decreased by 19.5%, and the diosgenin content increased by 175%, suggesting that there was a dynamic equilibrium relationship among the changes of active substances. This study aims at provide a basis and reference for the research of Monascus fermented foods by medicine food homology raw materials.