Monascus Fermentation Research Articles

Evaluation of differences in volatile flavor compounds between liquid-state and solid-state fermented Tartary buckwheat by Monascus purpureus

The differences in volatile flavor compounds (VFCs) between Monascus-solid-state fermented Tartary buckwheat (MSFTB) and Monascus-liquid-state fermented Tartary buckwheat (MLFTB) were investigated using electronic nose and gas chromatography-ion mobility spectrometry (GC-IMS) analysis. The study revealed several significant differences in the composition and abundance of VFCs between the two states. Compared to MSFTB, MLFTB exhibited notable increases in various elements including protein, crude fat, total flavonoids, total polyphenols, Monacolin K, Monascus pigments. Principal component analysis demonstrated significant increases in the production of specific VFCs in MLFTB compared to MSFTB. A total of 25 VFCs were identified through GC-IMS, including 9 esters, 7 alcohols, 5 ketones, and 4 aldehydes. The content of pleasant VFCs in MLFTB was significantly higher than in MSFTB. These compounds served as both VFCs and key aroma components during fermentation. In conclusion, the Monascus fermentation state played a crucial role in enhancing the flavor quality of Tartary buckwheat.

Optimisation of fermentation condition for production of hight monacolin k (mk) yield by monascus-strains

Monacolin K (MK), produced by Monascus fermentation, has significant hypolipidemic effects. In this study, under solid-state fermentation (SSF) quinoa was used as substrate to investigate the effect of the MK production by Monascus species quinoa. The results of the single factor experiment showed that the amount of the substrate loaded, addition of water to the substrate, and fermentation temperature change time have a significant effect on the MK production of Monascus-fermented quinoa. It was found that neither M. pilosus-fermented quinoa nor M. ruber-fermented quinoa produced citrinin. Consequently, these three factors were selected for the response surface optimization to determine the optimal fermentation process. The results showed that the optimal fermentation process of M. pilosus-fermented quinoa was as follows: quinoa loading amount of 30 g/300 ml, addition of 20 ml water to substrate, seed liquid inoculation volume of 10%, cultured at 30°C for 2 days, followed by a temperature change to 25°C and continued cultivation until 12 days. Under this fermentation process, the yield of MK reached 2.51 mg/g and without production of any citrinin. The optimal fermentation process of M. ruber-fermented quinoa was as follows: quinoa loading amount of 31 g/300 ml, water addition of substrate of 20 ml, seed liquid inoculation volume of 20%, cultured at 30°C for 2 days, followed by a temperature change to 25°C and continued cultivation until 12 days. Under this fermentation process, the yield of MK reached 3.22 mg/g and without any citrinin production. Bangladesh J. Bot. 53(3): 717-729, 2024 (September) Special

Lactic acid bacteria-assisted Monascus fermentation textured soy protein: Coloring plant-based meat and the dynamic changes of its physicochemical properties

Plant-based meat analogs have garnered considerable attention due to its benefits in reducing resource consumption, mitigating environmental pollution, enhancing animal welfare and human health. However, most plant-based products currently mimic the color of real meat by exogenously adding natural pigments. In this study, for the first time, Monascus. Ruber AS3.549 (MA) was employed as the primary pigment-producing strain, together with mixed lactic acid bacteria (LM) consisting of 12 different kinds of lactic acid bacteria as the auxiliary strain to ferment textured soy protein (TSP) for the production of plant-based meat products. TSP achieved the highest red pigment color value of 34.47 ± 0.91 U/g under the ideal fermentation conditions. Furthermore, the fermentation procedure greatly enhanced the physicochemical characteristics of TSP, with a notable rise of 39.84% in crude protein content and an impressive rise of 302.34% in soluble protein content. The water-holding capacity (WHC) and oil-holding capacity (OHC) experienced a substantial rise, while the color transitioned from yellow to deep red, with the level of redness rising by 295.26%. As a result, this work investigates a novel combination of strains capable of coloring TSP, significantly improving TSP quality, and serving as a reference for the future creation of plant-based meat products with desirable meat quality properties.

Effective enhancement of the ability of Monascus pilosus to produce lipid-lowering compound Monacolin K via perturbation of metabolic flux and histone acetylation modification

Monacolin K (MK), also known as lovastatin, is a polyketide compound with the ability to reduce plasma cholesterol levels and many other bio-activities. Red yeast rice (also named Hongqu) rich in MK derived from Monascus fermentation has attracted widespread attention due to its excellent performance in reducing blood lipids. However, industrial Monascus fermentation suffers from the limitations such as low yield of MK, long fermentation period, and susceptibility to contamination. In this study, we firstly blocked the competitive pathway of MK biosynthesis to create polyketide synthase gene pigA (the key gene responsible for the biosynthesis of Monascus azaphilone pigments) deficient strain A1. Then, based on the strategies to increase precursor supply for MK biosynthesis, acetyl-CoA carboxylase gene acc overexpression strains C1 and C2 were constructed with WT and A1 as the parent, respectively. Finally, histone deacetylase gene hos2 overexpression strain H1 was constructed by perturbation of histone acetylation modification. HPLC detection revealed all these four strains significantly increased their abilities to produce MK. After 14 days of solid-state fermentation, the MK yields of strains A1, C1, C2, and H1 reached 2.03 g/100 g, 1.81 g/100 g, 2.45 g/100 g and 2.52 g/100 g, which increased by 28.5 %, 14.7 %, 43.9 % and 36.1 % compared to WT, respectively. RT-qPCR results showed that overexpression of hos2 significantly increased the expression level of almost all genes responsible for MK biosynthesis after 5-day growth. Overall, the abilities of these strains to produce MK has been greatly improved, and MK production period has been shortened to 14 days from 20 days, providing new approaches for efficient production of Hongqu rich in MK.

Unveiling the potential of red koji polysaccharides: biosynthesis, extraction, and multifaceted biological activities.

Red koji polysaccharides, derived from the fermentation of Monascus, have been recognized for their health-enhancing properties. This article reviews their structural characteristics, biosynthesis pathways, and biological activities. It emphasizes the need for sustainable practices in fermentation and the optimization of extraction methods for scalable production. The significance of exploring the molecular mechanisms involved in their biosynthesis is also highlighted to enhance yield and efficiency. Research indicates that red koji polysaccharides possess diverse biological functions, beneficial for pharmaceutical applications due to their health benefits and minimal toxicity. The review points out the necessity for more detailed studies on key enzymes and genes in biosynthesis to improve production methods. It also identifies the current challenges in production scalability and extraction efficiency. Furthermore, while these polysaccharides show potential in pharmaceuticals, their clinical efficacy and mechanism of action in human subjects require further investigation. The review briefly explores potential structural modifications to improve their biological activities. The review concludes that red koji polysaccharides hold significant untapped potential, particularly in drug formulation. Future research should focus on overcoming current production and application challenges, including conducting clinical trials to validate their efficacy and exploring structural modifications for enhanced therapeutic benefits. This comprehensive understanding of red koji polysaccharides paves the way for their expanded application in the pharmaceutical industry. © 2024 Society of Chemical Industry.

Physiochemical Quality, Microbial Diversity, and Volatile Components of Monascus-Fermented Hairtail Surimi.

In order to study the effects and mechanism of Monascus on the quality of hairtail surimi, high-throughput sequencing technology, headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC/MS), and electronic nose techniques were used to investigate the changes in the quality, microbial diversity, and volatile flavor compounds of Monascus-fermented hairtail surimi (MFHS) during fermentation. The results showed that the total volatile basic nitrogen (TVB-N) index of hairtail surimi fermented by Monascus for 0-5 h met the requirements of the national standard. Among them, the 1 h group showed the best gel quality, which detected a total of 138 volatile substances, including 20 alcohols, 7 aldehydes, 12 olefins, 4 phenols, 12 alkanes, 8 ketones, 15 esters, 6 acids, 16 benzenes, 4 ethers, and 8 amines, as well as 26 other compounds. In addition, the dominant fungal microorganisms in the fermentation process of MFHS were identified, and a Spearman correlation analysis showed that 16 fungal microorganisms were significantly correlated with the decrease in fishy odor substances in the fermented fish and that 8 fungal microorganisms were significantly correlated with the increase in aromatic substances after fermentation. In short, Monascus fermentation can eliminate and reduce the fishy odor substances in hairtail fish, increase and improve the aromatic flavor, and improve the quality of hairtail surimi gel. These findings are helpful for revealing the mechanism of the quality formation of fermented surimi and provide guidance for the screening of starter culture in the future.

Effective degradation of anthraquinones in Folium Sennae with Monascus fermentation for toxicity reduce and efficacy enhancement

Folium Sennae are widely used around the world, mainly in purging and removal of endogenous active substances, such as anthraquinone and its derivatives. However, the potential toxicity of anthraquinones to the liver, kidney, and intestinal limits the application of Folium Sennae. In this study, we aimed at safe regulation of Folium Sennae to degrade anthraquinones, boosting medicinal properties and reducing toxicity and potency with Monascus fermentation. Monascus strains H1102 for Folium Sennae fermentation were selected as the initial strain which was capable of producing high yields of functional pigment and low yields of hazardous citrinin. The anthraquinone degradation rate reached 41.2%, with 212.2 U mL−1 of the pigment and approximately 0.038 mg L−1 of the citrinin under optimal fermentation conditions followed by response surface streamlining, which met the requirements of reducing toxicity, increasing efficiency of Monascus fermented Folium Sennae. Furthermore, the Monascus/Folium Sennae culture had no observable toxic effect on HK-2 and L-02 cells in vitro and further inhibited cell apoptosis and necrosis. Overall, our results showed that Monascus fermentation could provide an alternative strategy for toxicity reduction of herbal medicines as well as efficacy enhancement.

Adding genistein or luteolin decreased the yield of citrinin and without reducing pigments in yam solid-fermentation by Monascus.

Chinese yam fermented by Monascus, namely red mold dioscorea (RMD), has the potential of treating diseases. However, the production of citrinin limits the application of RMD. In the present study, the fermentation process of Monascus was optimized by adding genistein or luteolin to reduce citrinin yield. The results showed that citrinin in 25 g of Huai Shan yam was reduced by 48% and 72% without affecting the pigment yield by adding 0.2 g of luteolin or genistein, respectively, to a 250-mL conical flask after fermentation for 18 days at 28 °C, whereas the addition of luteolin increased the content of yellow pigment by 1.3-fold. Under optimal conditions, citrinin in 20 g of iron bar yam decreased by 55% and 74% after adding 0.2 g of luteolin or genistein. Luteolin also increased yellow pigment content by 1.2-fold. Ultra HPLC coupled to quadrupole time-of-flight mass spectrometry was used for the preliminary analysis of Monascus fermentation products. It was found that the amino acid types in RMD are similar to those in yams, but there are fewer polysaccharides and fatty acids. The results obtained in the present study showed that the addition of genistein or luteolin could reduce citrinin on the premise of increasing pigment yield, which laid a foundation for the better use of yams in Monascus fermentation. © 2023 Society of Chemical Industry.

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.

Bidirectional fermentation of Monascus and Mulberry leaves enhances GABA and pigment contents: establishment of strategy, studies of bioactivity and mechanistic

Bidirectional fermentation is a technology that utilizes fungi to ferment medicinal edible substrates, with synergistic and complementary advantages. In this work, a fermentation strategy was established to produce a high yield of γ-aminobutyric acid (GABA) and Monascus pigments (MPs) using Monascus and mulberry leaves (MLs). Firstly, the basic fermentation parameters were determined using single-factor experiments, followed by Plackett-Burman (PB) experimental design to identify MLs, glucose, peptone, and temperature as significant influencing factors. The fermentation parameters were optimized using an artificial neural network (ANN). Finally, the effects of bidirectional fermentation of MLs and Monascus were investigated by bioactivity analysis, microstructure observation, and RT-qPCR. The outcomes showed that the bidirectional fermentation significantly increased the bioactive content and promoted the secondary metabolism of Monascus. The established fermentation conditions were 44.2 g/L of MLs, 57 g/L of glucose, 15 g/L of peptone, 1 g/L of MgSO4, 2 g/L of KH2PO4, 8% (v/v) of inoculum, 180 rpm, initial pH 6, 32 °C and 8 days. The content of GABA reached 13.95 g/L and the color value of MPs reached 408.07 U/mL. This study demonstrated the feasibility of bidirectional fermentation of MLs and Monascus, providing a new idea for the application of MLs and Monascus.

The effect of rising Monascus fermented durian seed concentration on physicochemical and organoleptic properties of meat analog consisted of sweet potato flour and gluten

Meat analog (MA) is an innovative, versatile food product that has a texture, colour, and flavor which resembles beef but made from vegetable ingredients. MA can be prepared by combining the flour of sweet potato with gluten. To enhance the colour of MA, some colouring agents are recommended such as Monascus Fermented Durian Seed (MFDS). This study aimed to evaluate the effect of MFDS on the physicochemical and organoleptic properties of meat analog consisting of sweet potato flour and gluten. The experimental design employed a Randomized Complete Block Design (RCBD) with one factor, namely the concentration of MFDS which consist of five levels (0%, 0.2%, 0.4%, 0.6%, and 0.8%) each replicated five times. Findings revealed that MFDS had a significant effect on colour objectively and organoleptic properties (colour preference, taste, texture), but did not have any significant effect on moisture content and texture (hardness, cohesiveness, springiness). The higher the concentration MFDS, the higher redness, colour preference, and texture preference of meat analog. Based on performed organoleptic tests, the best treatment was the addition of 0.6% MFDS which produces meat analog with moisture content of 48.01%; lightness 54.4; redness 7.4; yellowness 13.9; chroma 15.3; o hue 63.4; hardness 1992.688 g; cohesiveness 0.696; springiness 0.941; and water activity (aw) 0.946.

Cytochrome P450 mediates the formation of four new citrinin metabolites

Citrinin (CIT) is one of by-products by Monascus fermentation with known nephrotoxicity. Except dihydro-citrinone, no other metabolites including the possible metabolic pathways have been found in vivo metabolism. In this study, we applied ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) to analyze and identify potential CIT metabolites in the human cytochrome 450 (P450) subtype system. Four new metabolites with liver microsomes incubation were first found, namely 3-hydroxy-citrinin (M1), 4,5-ene-citrinin (M2), 5-hydroxymethyl-citrinin (M3), and 7-hydroxy-citrinin (M4). We also found the distinguished levels of the four metabolites with the incubation of various P450 subtypes. According to the results of molecular docking prediction, it showed the metabolic correlation of CYP3A4 with M1, CYP1A2, CYP2C9, and CYP2D6 with M2, M3, and M4. The maximum level of M1 metabolite was found in the incubation with liver microsome and P450 subtypes. Moreover, M1 and M4 metabolites were found in mice's duodenum, jejunum, ileum, liver, kidney, and hippocampus, but not M2 and M3. These results indicated the mediation of citrinin metabolism by P450s. It also suggested the concentration differences of metabolites with the incubation of different P450 subtypes.

Investigation of monacolin K, yellow pigments, and citrinin production capabilities of Monascus purpureus and Monascus ruber (Monascus pilosus).

Red mold rice (RMR) is a traditional Chinese medicine prepared using Monascus fermentation. Monascus ruber ( pilosus) and Monascus purpureus have a long history of use as food and medicine. As an economically important starter culture, the relationship between the taxonomy of Monascus and production capabilities of secondary metabolites is crucial for the Monascus food industry. In this study, monacolin K, monascin, ankaflavin, and citrinin production by M. purpureus and M. ruber were genomically and chemically investigated. Our findings suggest that M. purpureus can produce monascin and ankaflavin in a correlated manner, whereas M. ruber produces monascin with minimum ankaflavin. M. purpureus is capable of producing citrinin; however, it is unlikely able to produce monacolin K. In contrast, M. ruber produces monacolin K, but not citrinin. We suggest that the current monacolin K content-related regulation of Monascus food should be revised, and labeling of Monascus species should be considered.

Monascus Yellow Pigment Production by Coupled Immobilized-Cell Fermentation and Extractive Fermentation in Nonionic Surfactant Micelle Aqueous Solution

Microbial fermentation with immobilized cells possesses many advantages. However, this fermentation mode is restricted to the production of extracellular products. Our previous study demonstrated that the extractive fermentation of Monascus spp. in nonionic surfactant micelle aqueous solution can export Monascus pigments that are supposed to be mainly intracellular products to extracellular culture broth and, in the meantime, extracellularly enhance the production of yellow pigments at a low pH condition; consequently, this makes the continuous production of yellow pigments with immobilized Monascus cells feasible. In this study, immobilized-cell fermentation and extractive fermentation in Triton X-100 micelle aqueous solution were successfully combined to continuously produce Monascus yellow pigments extracellularly. We examined the effects of cell immobilization and Triton X-100 on cell growth, pigment production, and pigment composition. In the repeated-batch extractive fermentation with immobilized cells, the biomass in Ca-alginate gel beads continued to grow and reached 21.2 g/L after seven batches, and dominant yellow pigments were produced extracellularly and stable for each batch. The mean productivity of the extracellular yellow pigments reached up to 22.31 AU410 nm/day within the first four batches (13 days) and 19.7 AU410 nm/day within the first seven batches (25 days). The results also provide a new strategy for producing such intracellular products continuously and extracellularly.

Genetic responses to adding nitrates to improve hydrophilic yellow pigment in Monascus fermentation.

Nitrates can stimulate the biosynthesis of hydrophilic yellow pigments (HYPs) in Monascus ruber CGMCC 10910. To explore the molecular mechanisms whereby nitrates (NaNO3 and NH4NO3) regulate HYP production, an integrated transcriptomic and proteomic analysis was conducted in this study. Nitrate addition led to an approximately 75% higher HYP production compared with the untreated group, especially compounds Y3 and Y4. Comparative transcriptomic analysis found that mpigsA, H, K, L, and P genes involved in yellow pigment biosynthesis were significantly upregulated. In addition, pigment biosynthesis-related (carbon catabolism, amino acid metabolism, polyketide synthesis, and fatty acid metabolism) genes were upregulated to provide precursors and energy for HYP biosynthesis and cell growth. Secretion-related (cytomembrane ergosterol biosynthetic, and transport) pathways were also noticeably regulated to accelerate transmembrane transport of HYPs. Meanwhile, proteomicanalysis showed that nitrates improved the protein expression of hybrid polyketide synthase-nonribosomal peptide synthetase, oxidoreductase, glucoamylase, endo-1,4-beta-xylanase, O-acetylhomoserine, and isocitrate lyase to enhance HYP production. These findings demonstrated the regulatory mechanism of nitrates for enhancing HYP production in Monascus. KEY POINTS: • Nitrates stimulated the biosynthesis of Monascus hydrophilic yellow pigments (HYPs) • Nitrates affected transcriptional level of pigment biosynthesis- and transport genes • Increased expression of hybrid PKS-NRPS and transporters promoted production of HYPs.

Application of Cellulase for Contributing Phenolic Release and Conversion in Oats (Avena sativa L.) During Microbial Fermentation.

In this work, Monascus fermentation and cellulase hydrolysis (MCF) of oats (Avena sativa L.) to release and convert phenolic fraction was investigated. Results showed the fungus Monascus grew well with a biomass of 27.03mg/g glucosamine equivalent in MCF, following the destruction of oat cellular structures. SDS-PAGE revealed lots of enzymes were regulated with the α-amylase and FPase activity achieved 139.25 U/g and 1.84 U/g in MCF, respectively. Compared with unfermented oats, content of the total phenolic fractions was increased by 19.2 times in MCF, suggesting a phenolic release process occurred during fermentation. Moreover, the soluble-free chlorogenic acid upregulated to 510.00mg/kg whereas the insoluble-bound ferulic acid downregulated to 193.36mg/kg in MCF, indicating a transformation process of chlorogenic acid from ferulic acid in oats was enhanced. Based on this, a possible pathway of phenolic release and conversion in oats during fermentation with Monascus spp. was revealed. This study was helpful to enrich the theory of microbial metabolism and transformation in grain materials.

Utilization of durian seed for Monascus fermentation and its application as a functional ingredient in yogurt

As a widely consumed fermented milk product, yogurt undergoes constant development to increase its functional properties. Monascus purpureus-fermented durian seed, which has been proven to possess antioxidative properties, has the potential to improve yogurt properties. This study aimed to analyze the use of Monascus-fermented durian seed (MFDS) as a functional ingredient in yogurt and its effect on physicochemical properties, lactic acid bacteria (LAB) count, antioxidative properties, and consumer acceptability of set-type yogurt during refrigeration. Changes in physicochemical properties, including color, pH, titratable acidity, syneresis, LAB count, total phenolic content (TPC), and antioxidant activity were evaluated at 7-day intervals during 14 days of refrigerated storage (4 °C). Sensory evaluations were carried out for freshly made samples after 7 days of storage. The results showed that the addition of MFDS to yogurt gave significant effects on some of the parameters measured. Yogurt with added MFDS powder produced a more red color (L = 88.55 ± 1.28, a* = 2.63 ± 0.17, b* = 11.45 ± 1.15, c = 11.75 ± 1.15, H = 77.00 ± 0.64), reached the highest TPC (2.21 ± 0.46 mg/GAE g), antioxidant activity (0.0125 ± 0.0032 mg GAE/g), and syneresis (5.24 ± 0.51%) throughout 14 days of storage. The addition of MFDS only gave a slight difference to pH and titratable acidity, while no significant difference was made for LAB count. For sensory evaluation, the addition of MFDS, particularly the ethanol extract, to yogurt was well-liked by panelists. Citrinin content in MFDS yogurt can be decreased under the limits set. Overall, the addition of MFDS has a high potential of improving yogurt properties, particularly its antioxidative properties.Graphical

Study on production of yellow pigment from potato fermented by Monascus

Aiming at the problem of low yield of monascus yellow pigment liquid fermentation, a new process for producing yellow pigment by liquid fermentation of Monascus from potato has been designed. In this process, the color value of intracellular yellow pigment reaches 341.2U/g, which is 58.73% higher than that of conventional liquid fermentation; the color value of extracellular yellow pigment reached 168U/g, which was 38.39% higher than that of conventional liquid fermentation. It was identified by liquid chromatography-mass spectrometry that the intracellular yellow pigments produced by this method were mainly Monascus and Monascus anka. The yields of these two pigments were increased by 33.91% and 84.32%, and their concentrations were 274.6 μg/mL and 167.1 μg/mL, respectively. In addition, the content of citrinin produced by the new process method was 97.85% lower than that of the original Monascus C100 strain and the fermentation broth has good stability. The electronic nose analysis of the fermentation broth indicated that the flavor substances were mainly alcohols and aldehydes and ketones. The antioxidant activity of the fermentation broth is good, for example: the reducing power is comparable to the reducing power of 350 μg/mL VC, the maximum DPPH free radical scavenging rate is 69.81%, the IC50 value of the superoxide anion free radical scavenging rate is 0.873 mL, ABTS The maximum free radical scavenging rate was comparable to the VC scavenging rate of 0.0035 mg/mL, and the maximum scavenging rate of hydroxyl radicals was 87.95%.

Co-culture of Monascus purpureus with Saccharomyces cerevisiae: A strategy for pigments increment and citrinin reduction

For centuries, Monascus purpureus pigments have been used traditionally as a natural food colorant in Asian countries. However, this way is not practical to use in different products due to the production of citrinin by Monascus sp. Co-culture of Monascus purpureus and Saccharomyces cerevisiae is one of the biological ways which significantly reduces citrinin. In this research, the live cells of S. cerevisiae at three concentrations of 103, 104, and 105 cells/mL were used on the 8th, 11th, and 13th days of the M. purpureus fermentation. Analysis of Citrinin and measurement of pigments absorbance were conducted by HPLC and spectrophotometry, respectively. The result indicated that the addition of live cells of S. cerevisiae to Monascus culture improves pigments production and reduces citrinin. Yellow intracellular pigment on day 8 of fermentation at 105 cells/mL yeast cell with the absorbance of 18.40 AU revealed the highest absorbance which was more than three times greater than the control one (5.54 AU). The HPLC results demonstrated that citrinin content at 105 cells/mL live yeast cell on the 13th day of Monascus fermentation (0.9 ppm) was five fold less than its content in the control (4.43 ppm). Above all, results proved that the co-culture of M. purpureus and S.cerevisiae can play an important role to produce not only more portions of pigments but also can warrant more safety.

A systematic study of the production of Monacolin K by solid state fermentation of Monascus ruber

Monacolin K is one of the bioactive substances produced by Monascus ruber during fermentation. The multi-factors and their interactions on the effect of solid-state fermentation of Monascus for high yield of monacolin K were attractive to industrial production. A detailed study of 7 single-factor experiments and a series of experiments with Plackette-Burman and Box-Benhnken design, data fitting and modeling, and analyzing the visual 3D response surface plots for investigation of the key factors for Monacolin K production. The results showed that initial moisture (50 ~ 55%) and bran content (4.5 ~ 5.5%) as the key factors of transport for nutrients and oxygen during the solid-state fermentation (SSF) process of Monascus. Under the optimal conditions, a temperature shifting of the SSF with a higher Monacolin K yield of 14.53 ± 0.16 mg·g− 1 compared with the content of monacolin K in the commercially available functional red yeast rice of 8 mg g− 1.