g-Aminobutyric Acid (GABA) is a secondary metabolite produced in Monascus-fermented food. The mycotoxin (citrinin), another major secondary metabolite, is neurotoxic to humans and thus it diminishes the social acceptability of Monascus-Fermented Rice (MFR). The study was aimed to enrich GABA content and to reduce citrinin level in MFR. Plackett-Burman experimental design and response surface methodology was used to optimize a fermentation medium for a high amount of GABA production with less amount of citrinin by Monascus purpureus Microbial Type Culture Collection and Gene Bank (MTCC) 369 under solid state fermentation (SSF). Statistically optimized nutrient parameters for MFR were lactose 0.054 g/g, alanine 2 mg/g, malt extract 37.4 mg/g, and ZnSO 4 0.3 mg/g. The yield of GABA and citrinin in optimized conditions were found to be 24 ± 0.27 mg/g and 3.3 ± 0.19 µg/g, respectively. The optimized medium parameters can be used and explored to produce high amount of GABA with low citrinin in MFR.

Monascus-fermented rice (MFR) has been used in traditional Chinese and Japanese medicine for the revitalization of blood, digestion problems, and cardiovascular disorders. Through a biotechnological approach, MFR is produced by the solid-state fermentation of rice by Monascus spp. MFR has remarkable therapeutic properties as it contains several bioactive compounds, and dimerumic acid is one of the important siderophore-based antioxidant fermentative metabolites found in it. This study aimed to screen out the medium composition for the production of dimerumic acid (DMA) and evaluate its antioxidant potential. Different strains of Monascus purpureus Microbial Type Culture Collection & Gene Bank (MTCC) 410, 369, 1090 and Monascus ruber MTCC 1880, 2326 and Monascus pilosus CBS 286.34, CBS 290.34 with different solid substrate were screened for maximum yield of DMA. Solid-state fermentation of longgrain rice (Oryza sativa) by Monascus pilosus CBS 290.34 was the best for DMA production. The optimized medium parameters in rice for the highest yield of DMA were glucose (75.13 mg/g), soya extract (19.33 mg/g), malt extract (35.14 mg/g), and calcium carbonate (0.29 mg/g). The predicted values for medium parameters were in good agreement with the experimental data. MFR enriched with DMA showed potent antioxidant and lipid lowering capacity in both in vitro and in vivo. It can be explored further for the development of nutraceuticals as a natural antioxidant.