A Simple and Rapid Approach for Removing Citrinin while Retaining Monacolin K in Red Mold Rice

Monascus species-fermented red mold rice (RMR) has been regarded as a popular hypolipidemic functional food because it contains monacolin K, an inhibitor of de novo cholesterol synthesis. However, the safety of RMR is always an issue because citrinin is present in RMR and is reported to be hepatotoxic and nephrotoxic. The present study was therefore to develop a postprocess to remove citrinin yet retain monacoln K in the RMR preparation. We found that phosphate-ethanol extraction was effective for the removal citrinin, yet it could retain monacolin K, because the former was more hydrophilic than the latter in phosphate-ethanol solution. Ethanol, phosphate, and extraction time were optimized as factors of response surface methodology (RSM). It was found that the optimal RSM condition was 45% ethanol, 1.5% phosphate, and extraction for 70 min. Under this optimal condition, 91.6% citrinin was removed and 79.5% monacolin K was retained in the final RMR.