IMPACT OF THE FERMENTATION CONDITIONS ON PIGMENT, MONACOLIN K, AND CITRININ PRODUCTION OF Monascus purpureus Went

Abstract

Red fermented rice, commonly used as a natural food colorant, contains monacolin K (MK), a bioactive compound known for its cholesterol-lowering properties. However, concerns have emerged regarding its safety due to the potential production of citrinin (CT), a toxic byproduct synthesized during fermentation. To promote safer utilization, this study aimed to determine a fermentation protocol for producing Monascus-biopigment that yields high MK content while minimizing CT concentrations. The study investigated the impact of various parameters over a 10–day fermentation period, including substrate type, initial pH, 0.5% ethanol supplementation, and incubation temperature. Monascus-biopigments were extracted using a 70% (v/v) ethanol solution, and concentrations of both MK and CT were quantified using HPLC-UV-Vis analysis. Among the tested conditions, the control setup, utilizing rice as the fermentation substrate, no pH modification, and incubation at 30°C, resulted in the highest biopigment concentration. Meanwhile, the C3 treatment, which utilized corn as a substrate, a pH adjusted to 2.5, with 0.5% ethanol supplementation, and fermentation temperature of 26°C, yielded the highest MK-to-CT ratio. Although using corn without altering pH enhanced pigment, MK, and CT, lowering the pH to 2.5 significantly suppressed CT concentration. Moreover, the combination of ethanol supplementation and lower temperature further enhanced MK production. In conclusion, the findings provide valuable insights into optimizing fermentation conditions for safer and more potent Monascus-biopigment, supporting its potential application in the food and nutraceutical industries.