Determination of monacolin K and citrinin in red mold dioscorea and driedshrimp products using ultra high-performance liquid chromatography

In this study, red mold dioscorea (RMD) was utilized as a natural colorant to produce dried whiteleg shrimp (Litopenaeus vannamei). Whiteleg shrimp dyed with 50% diluted liquid RMD had a favorable appearance compared to control and undiluted liquid RMD. Dioscorea (Dioscorea hispida Dennst.) or bitter yam flour was used as a substrate in Monascus purpureus TISTR 3615 submerged fermentation to produce RMD. Dioscorea flour concentrations in a range of 10-50 g/L and various nitrogen sources at 4 g/L were investigated. The study showed that 10 g/L of diosorea flour and monosodium glutamate were chosen for further fermentation. Two major secondary metabolites in Monascus fermentation named monacolin K and citrinin, were determined in liquid RMD and dried shrimp products using UHPLC-DAD. Results showed that monacolin K were not detected in liquid RMD and all dried shrimp samples. Although, citrinin at a concentration of 2.06 mg/L was found in liquid RMD. Thus, RMD from the medium containing diosorea flour as a fermentation substrate can be used as colorant in dried shrimp production or other seafood products. However, the citrinin content in pigments remains an issue of concern.