Fabricating Pea Protein Micro-Gel-Stabilized Pickering Emulsion as Saturated Fat Replacement in Ice Cream.

Unsaturated fat replacement should be used to reduce the use of saturated fat and trans fatty acids in the diet. In this study, pea protein micro-gels (PPMs) with different structures were prepared by microparticulation at pH 4.0-7.0 and named as PPM (pH 4.0), PPM (pH 4.5), PPM (pH 5.0), PPM (pH 5.5), PPM (pH 6.0), PPM (pH 6.5), and PPM (pH 7.0). Pea protein was used as a control to evaluate the structure and interfacial properties of PPMs by particle size distribution, Fourier transform infrared spectroscopy (FTIR), free sulfhydryl group content, and emulsifying property. PPM (pH 7.0) was suitable for application in O/W emulsion stabilization because of its proper particle size, more flexible structure, high emulsifying activity index (EAI) and emulsifying stability index (ESI). The Pickering emulsion stabilized by PPM (pH 7.0) had a uniform oil droplet distribution and similar rheological properties to cream, so it can be used as a saturated fat replacement in the manufacture of ice cream. Saturated fat was partially replaced at different levels of 0%, 20%, 40%, 60%, 80%, and 100%, which were respectively named as PR0, PR20, PR40, PR60, PR80, and PR100. The rheological properties, physicochemical indexes, and sensory properties of low-saturated fat ice cream show that PPM (pH 7.0)-stabilized emulsion can be used to substitute 60% cream to manufacture low-saturated fat ice cream that has high structural stability and similar melting properties, overrun, and sensory properties to PR0. The article shows that it is feasible to prepare low-saturated fat ice cream with PPM (pH 7.0)-stabilized Pickering emulsion, which can not only maintain the fatty acid profile of the corn oil used, but also possess a solid-like structure. Its application is of positive significance for the development of nutritious and healthy foods and the reduction of chronic disease incidence.

Improving the storage quality and suppressing off-flavor generation of winter jujube by precise micro-perforated MAP.

Introduction: Traditional modified atmosphere packaging (MAP) cannot meet the preservation requirements of winter jujube, and the high respiration rate characteristics of winter jujube will produce an atmosphere component with high CO2 concentration in traditional MAP. Micro-perforated MAP is suitable for the preservation of winter jujube due to its high permeability, which can effectively remove excess CO2 and supply O2. In this study, a microporous film preservation system that can be quickly applied to winter jujube was developed, namely PMP-MAP (precise micro-perforated modified atmosphere packaging). An experiment was designed to store winter jujube in PMP-MAP at 20°C and 2°C, respectively. The quality, aroma and antioxidant capacity, etc. of winter jujube at the storage time were determined. Methods: In this study, the optimal micropore area required for microporous film packaging at different temperatures is first determined. To ensure the best perforation effect, the effects of various factors on perforation efficiency were studied. The gas composition within the package was predicted using the gas prediction equation to ensure that the gas composition of the perforated package achieved the desired target. Finally, storage experiments were designed to determine the quality index of winter jujube, including firmness, total soluble solids, titratable acid, reddening, and decay incidence. In addition, sensory evaluation, aroma and antioxidant capacity were also determined. Finally, the preservation effect of PMP-MAP for winter jujube was evaluated by combining the above indicators. Results and discussion: At the end of storage, PMP-MAP reduced the respiration rate of winter jujube, which contributed to the preservation of high total soluble solids and titratable acid levels, and delayed the reddening and decay rate of winter jujube. In addition, PMP-MAP maintained the antioxidant capacity and flavor of winter jujube while inhibiting the occurrence of alcoholic fermentation and off-flavors. This can be attributed to the effective gas exchange facilitated by PMP-MAP, thereby preventing anaerobic stress and quality degradation. Therefore, the PMP-MAP approach is an efficient method for the storage of winter jujube.

Physicochemical properties and in vitro digestion behavior of emulsion micro-gels stabilized by κ-carrageenan and whey protein: Effects of sodium alginate addition.

Emulsion micro-gels exhibit significant potential as functional ingredients for modifying food texture, replacing saturated fats, or serving as templates for the controlled release of bioactive compounds. Structural design principles are being applied more frequently to develop innovative emulsion micro-gels. In this paper, whey protein concentrate (WPC), κ-carrageenan and sodium alginate (SA) were utilized for preparing emulsion micro-gels. To reveal the regulation mechanism of the structural and physicochemical properties of emulsion micro-gels on lipid digestion, the influence of SA additions on the structural, physicochemical properties and in vitro digestion behavior of κ-carrageenan/WPC-based emulsion micro-gel were explored. The FTIR results suggest that the emulsion micro-gels are formed through non-covalent interactions. With the increase of SA addition (from 0.7 g/100 mL to 1.0 g/100 mL), the decreased mean droplet size, the increased hardness, elasticity indexes, and water holding capacity, the reduced the related peak times all indicated that the emulsion micro-gels exhibit enhanced rheological, stability, and mechanical properties. It can be concluded from the microstructure, particle size distribution of the emulsion micro-gels during simulated digestion and free fatty acid release that both κ-carrageenan/WPC-based emulsion micro-gel and κ-carrageenan/WPC/SA-based emulsion micro-gel can inhibit lipid digestion due to the ability to maintain structural stability and hindering the penetration of bile salts and lipase through the hydrogel networks. And the ability is regulated by the binding properties the gel matrix and oil droplets, which determine the structure and physicochemical properties of emulsion micro-gels. The research suggested that the structure of emulsion micro-gels can be modified to produce various lipid digestion profiles. It may be significant for certain practical application in the design of low-fat food and controlled release of bioactive agents.

Modification of pea dietary fibre by superfine grinding assisted enzymatic modification: Structural, physicochemical, and functional properties.

Using the optimal extraction conditions determined by response surface optimisation, the yield of soluble dietary fibre (SDF) modified by superfine grinding combined with enzymatic modification (SE-SDF) was significantly increased from 4.45 % ±â€¯0.21 % (natural pea dietary fibre) to 16.24 % ±â€¯0.09 %. To further analyse the modification mechanism, the effects of three modification methods-superfine grinding (S), enzymatic modification (E), and superfine grinding combined with enzymatic modification (SE)-on the structural, physicochemical, and functional properties of pea SDF were studied. Nuclear magnetic resonance spectroscopy results showed that all four SDFs had α- and ß-glycosidic bonds. Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy results showed that the crystal structure of SE-SDF was most severely damaged. The Congo red experimental results showed that none of the four SDFs had a triple-helical structure. Scanning electron microscopy showed that SE-SDF had a looser structure and an obvious honeycomb structure than other SDFs. Thermogravimetric analysis, particle size, and zeta potential results showed that SE-SDF had the highest thermal stability, smallest particle size, and excellent solution stability compared with the other samples. The hydration properties showed that SE-SDF had the best water solubility capacity and water-holding capacity. All three modification methods (S, E, and SE) enhanced the sodium cholate adsorption capacity, cholesterol adsorption capacity, cation exchange capacity, and nitrite ion adsorption capacity of pea SDF. Among them, the SE modification had the greatest effect. This study showed that superfine grinding combined with enzymatic modification can effectively improve the SDF content and the physicochemical and functional properties of pea dietary fibre, which gives pea dietary fibre great application potential in functional foods.

Effects of natural wax types on the physicochemical properties of starch/gelatin edible films fabricated by extrusion blowing.

To address the limitation of strong hydrophilicity of edible films, starch/gelatin (S/G) films incorporated with natural waxes (beeswax (BW), candelilla wax (CL), and carnauba wax (CB)) were fabricated by extrusion blowing. Rheological analysis demonstrated that the incorporation of natural waxes reduced storage modulus and complex viscosity of S/G blends. BW and CL weakened molecular interactions among film components, whereas CB did not. CB exhibited the strongest crystalline behavior after film formation. The degree of starch gelatinization and water vapor barrier property of films depended on wax type. The presence of waxes increased the water resistance and surface hydrophobicity of the films. However, CL and BW addition decreased the tensile strength of films. The highest water contact angle (102.6°), strongest thermal stability, and lowest water vapor permeability were found in S/G-BW film, which could be the optimal choice to produce highly hydrophobic edible films.

The Loading of Epigallocatechin Gallate on Bovine Serum Albumin and Pullulan-Based Nanoparticles as Effective Antioxidant.

Due to its poor stability and rapid metabolism, the biological activity and absorption of epigallocatechin gallate (EGCG) is limited. In this work, EGCG-loaded bovine serum albumin (BSA)/pullulan (PUL) nanoparticles (BPENs) were successfully fabricated via self-assembly. This assembly was driven by hydrogen bonding, which provided the desired EGCG loading efficiency, high stability, and a strong antioxidant capacity. The encapsulation efficiency of the BPENs was above 99.0%. BPENs have high antioxidant activity in vitro, and, in this study, their antioxidant capacity increased with an increase in the EGCG concentration. The in vitro release assays showed that the BPENs were released continuously over 6 h. The Fourier transform infrared spectra (FTIR) analysis indicated the presence of hydrogen bonding, hydrophobic interactions, and electrostatic interactions, which were the driving forces for the formation of the EGCG carrier nanoparticles. Furthermore, the transmission electron microscope (TEM) images demonstrated that the BSA/PUL-based nanoparticles (BPNs) and BPENs both exhibited regular spherical particles. In conclusion, BPENs are good delivery carriers for enhancing the stability and antioxidant activity of EGCG.

Fabrication and Characterization of Chitosan-Pea Protein Isolate Nanoparticles.

Chitosan (CS) and pea protein isolate (PPI) were used as raw materials to prepare nanoparticles. The structures and functional properties of the nanoparticles with three ratios (1:1, 1:2 1:3, CS:PPI) were evaluated. The particle sizes of chitosan-pea protein isolate (CS-PPI) nanoparticles with the ratios of 1:1, 1:2, and 1:3 were 802.95 ± 71.94, 807.10 ± 86.22, and 767.75 ± 110.10 nm, respectively, and there were no significant differences. Through the analysis of turbidity, endogenous fluorescence spectroscopy and Fourier transform infrared spectroscopy, the interaction between CS and PPI was mainly caused by electrostatic mutual attraction and hydrogen bonding. In terms of interface properties, the contact angles of nanoparticles with the ratio of 1:1, 1:2, and 1:3 were 119.2°, 112.3°, and 107.0°, respectively. The emulsifying activity (EAI) of the nanoparticles was related to the proportion of protein. The nanoparticle with the ratio of 1:1 had the highest potential and the best thermal stability. From the observation of their morphology by transmission electron microscopy, it could be seen that the nanoparticles with a ratio of 1:3 were the closest to spherical. This study provides a theoretical basis for the design of CS-PPI nanoparticles and their applications in promoting emulsion stabilization and the delivery of active substances using emulsions.

Time-series transcriptome comparison reveals the gene regulation network under salt stress in soybean (Glycine max) roots.

BACKGROUND: Soil salinity is a primary factor limiting soybean (Glycine max) productivity. Breeding soybean for tolerance to high salt conditions is therefore critical for increasing yield. To explore the molecular mechanism of soybean responses to salt stress, we performed a comparative transcriptome time-series analysis of root samples collected from two soybean cultivars with contrasting salt sensitivity. RESULTS: The salt-tolerant cultivar 'Qi Huang No.34' (QH34) showed more differential expression of genes than the salt-sensitive cultivar 'Dong Nong No.50' (DN50). We identified 17,477 genes responsive to salt stress, of which 6644 exhibited distinct expression differences between the two soybean cultivars. We constructed the corresponding co-expression network and performed Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results suggested that phytohormone signaling, oxidoreduction, phenylpropanoid biosynthesis, the mitogen-activated protein kinase pathway and ribosome metabolism may play crucial roles in response to salt stress. CONCLUSIONS: Our comparative analysis offers a comprehensive understanding of the genes involved in responding to salt stress and maintaining cell homeostasis in soybean. The regulatory gene networks constructed here also provide valuable molecular resources for future functional studies and breeding of soybean with improved tolerance to salinity.

Methyl salicylate affects the lipophilic and hydrophilic antioxidant capacities of apricot by regulating carotenoid biosynthesis and phenolic metabolism.

The carotenoid biosynthesis and phenolic metabolism were studied to explain the effect of methyl salicylate (MeSA) on the lipophilic antioxidant capacity (LAC) and hydrophilic antioxidant capacity (HAC) in apricot during postharvest storage. Our results indicated that the HAC of apricot was higher than LAC and mainly responsible for total antioxidant capacity of apricot. Preharvest spraying of MeSA (0.2 mmol L-1) could improve the value of HAC but declined LAC of apricot. The enhanced HAC in MeSA treated apricot was positively related to the increased content of phenolics, especially to (+)-catechin, which was catalyzed by the enzymes related to phenolic metabolism. While, the decline of LAC in apricot treated by MeSA could be attributed to the inhibition of carotenoids accumulation, which was regulated by carotenogenic genes. We concluded that MeSA could affect the lipophilic and hydrophilic antioxidant capacity of apricot by regulating carotenoid biosynthesis and phenolic metabolism.

Integrative analyses of metabolome and transcriptome reveals metabolomic variations and candidate genes involved in sweet cherry (Prunus avium L.) fruit quality during development and ripening.

Sweet cherry (Prunus avium L.), one of the most appreciated and most important commercial temperate fruits, has high sensory quality and nutritional value. Investigating its metabolic variations provides valuable information on the formation of fruit quality. In this study, widely targeted LC-MS/MS based metabolomics was used to identify and quantify metabolic changes during 'Black Pearl' sweet cherry development and ripening. A total of 263 significant differentially expressed metabolites (DEMs) were detected during the four fruit-development stages. Significant differences were observed in the composition and content of compounds in the four stages of cherry development, especially sugars, organic acids, and flavonoids. Moreover, transcriptome analysis provided a molecular basis for metabolic variations during fruit development. A total of 6724 significant differentially expressed genes (DEGs) were identified. Further correlation analysis of major DEMs and DEGs showed that 19 key DEGs were involved in sugar metabolism, 23 key DEGs in organic acid metabolism, and 13 key DEGs in flavonoid metabolism. The upregulated genes involved in the flavonoid pathway probably play an important role in regulating the rapid increase of anthocyanin content during fruit development. These comprehensive analysis data provide a better understanding to improve fruit quality traits based on molecular and metabolic levels.

Characterization and Caco-2 Cell Transport Assay of Chito-Oligosaccharides Nano-Liposomes Based on Layer-by-Layer Coated.

Chito-oligosaccharides (COSs) were encapsulated by the film-ultrasonic method into three nano-liposomes, which were uncoated liposomes (COSs-Lip), chitosan-coated liposomes (CH-COSs-Lip), and sodium alginate (SA)/chitosan (CH)-coated liposomes (SA/CH-COSs-Lip). The physicochemical and structural properties, as well as the stability and digestive characteristics, of all three nano-liposomes were assessed in the current study. Thereafter, the characteristics of intestinal absorption and transport of nano-liposomes were investigated by the Caco-2 cell monolayer. All nano-liposomes showed a smaller-sized distribution with a higher encapsulation efficiency. The ζ-potential, Z-average diameter (Dz), and polydispersity index (PDI) demonstrated that the stability of the SA/CH-COSs-Lip had much better stability than COSs-Lip and CH-COSs-Lip. In addition, the transport of the nano-liposomes via the Caco-2 cell monolayer indicated a higher transmembrane transport capacity. In summary, the chitosan and sodium alginate could serve as potential delivery systems for COSs to fortify functional foods and medicines.

Influence of Whey Protein Micro-Gel Particles and Whey Protein Micro-Gel Particles-Xanthan Gum Complexes on the Stability of O/W Emulsions.

Appropriate pretreatment of proteins and addition of xanthan gum (XG) has the potential to improve the stability of oil-in-water (O/W) emulsions. However, the factors that regulate the enhancement and the mechanism are still not clear, which restricts the realization of improving the emulsion stability by directional design of its structure. Therefore, the effects of whey protein micro-gel particles (WPMPs) and WPMPs-XG complexes on the stability of O/W emulsion were investigated in this article to provide theoretical support. WPMPs with different structures were prepared by pretreatment (controlled high-speed shear treatment of heat-set WPC gels) at pH 3.5-8.5. The impact of initial WPC structure and XG addition on Turbiscan Indexes, mean droplet size and the peroxide values of O/W emulsions was investigated. The results indicate that WPMPs and XG can respectively inhibit droplet coalescence and gravitational separation to improve the physical stability of WPC-stabilized O/W emulsions. The pretreatment significantly enhanced the oxidative stability of WPC-stabilized O/W emulsions. The addition of XG did not necessarily enhance the oxidative stability of O/W emulsions. Whether the oxidative stability of the O/W emulsion with XG is increased or decreased depends on the interface structure of the protein-XG complex. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.

Effect of lipids with different physical state on the physicochemical properties of starch/gelatin edible films prepared by extrusion blowing.

The effects of various physical state lipids (rapeseed oil (RO), shortening (ST), beeswax (BW)), on the physicochemical properties of starch (S) (hydroxypropyl distarch phosphate (HP), oxidized hydroxypropyl starch (OS))/gelatin (G) blown films were studied. S/G-lipid blends showed decreased storage modulus and complex viscosity. The formation of hydrogen bonds was inhibited by the ST and BW, but facilitated by the RO. Compared with BW and ST, RO was more effective to promote the melted and fractured of starch. Lipids addition promoted the compatibility of starch and gelatin. The presence of the lipids significantly improved the surface hydrophobicity, mechanical, water vapor barrier and water resistance properties of S/G films. S/G-RO films exhibited the strongest surface hydrophobicity and tensile strength, while HP/G-BW film showed the strongest water resistance and water vapor barrier properties. These results revealed that the appropriate lipids could be used to produce S/G-lipid films with desirable physicochemical properties.

Influence of initial protein structures and xanthan gum on the oxidative stability of O/W emulsions stabilized by whey protein.

In this article, oil-in-water (O/W) emulsions stabilized by natural whey protein concentrate (WPC) and microparticulated whey protein (MWP) and their mixtures with xanthan gum (XG) were prepared to investigate the lipid oxidative stability of O/W emulsions with the same interfacial composition but different interfacial structures. High-performance size exclusion chromatography, Fourier transform infrared spectrometry, X-ray diffraction analysis and steady-state fluorescence spectroscopy were used to reveal the differences in the structures of natural whey protein and the microparticulated whey proteins (MWP, pH 3.5-8.5). Dispersions of the proteins (70% w/w) and XG (30% w/w) were mixed to prepare the mixtures (protein-XG). Emulsions of 60% peanut oil that were stabilized by the proteins and the protein-XG mixtures were subjected to oxidation. In addition, the peroxide values (PVs) were measured to evaluate the oxidative stability of each emulsion. The MWP(pH 4.5)-XG and MWP(pH 6.5)-XG-stabilized emulsions showed high oxidative stabilities that were not significantly different from each other. The results indicated that a single complex layer formed by the spherical protein microparticles and XG can better inhibit the lipid oxidation of O/W emulsions than a double layer. This study has significant implications for the development of novel structures containing lipid phases that are susceptible to oxidation.

Effect of microparticulation and xanthan gum on the stability and lipid digestion of oil-in-water emulsions stabilized by whey protein.

Since lipid digestion is an interfacial process, food emulsions are increasingly being seen as a mechanism for controlling lipid uptake. Oil-in-water emulsions stabilized by whey protein (WP) and protein-xanthan gum (XG) mixtures were designed to investigate the influence of interfacial structures on lipid digestion using an in vitro digestion model. The interfacial layers with different structures were designed using microparticulated whey protein (MWP) and MWP-XG mixtures. The increase in the volume average diameter of proteins indicated that the WPs aggregated to form micro-particles during microparticulation. The increase in the protein surface hydrophobicity index and the measurement results from the Magnetic Resonance Imaging System indicated that the protein hydrophilic groups were embedded and that the protein hydrophobic groups were exposed. Under in vitro conditions, the emulsions stabilized by microparticulated whey proteins and protein-XG mixtures were more stable than the WP emulsions, and the microparticulated whey proteins and protein-XG mixtures were more effective for decreasing the digestion rate, as shown by the stability analysis and free fatty acid release rates. These results help elucidate the influence of the interfacial structure on lipid digestion. The control of lipid digestibility within the gastrointestinal tract might be important for the design and development of reduced-fat foods and novel functional foods for controlling bioactive release.

Investigation of Citrinin and Pigment Biosynthesis Mechanisms in Monascus purpureus by Transcriptomic Analysis.

Monascus purpureus YY-1 is widely used in food colorant production in China. Our previous study clearly illustrated the whole-genome data for YY-1 and provided useful insight into evolutionary research and industrial applications. However, the presence of citrinin, which has nephrotoxic, hepatotoxic, and carcinogenic activities, has attracted attention to the safety of Monascus products. In an effort to reduce the harmful effects of citrinin in Monascus-related products, a random mutant of M. purpureus YY-1 with low citrinin production (designated as "winter") was obtained in this study. To analyze the biosynthesis and regulation mechanisms of pigment and citrinin, a transcriptomic analysis of the M. purpureus YY-1 and winter strains was performed. Comparative transcriptomic analysis reveals pksCT, the essential gene for citrinin synthesis, showed a low expression level in M. purpureus YY-1 and winter, which suggested there might be isoenzymes in M. purpureus YY-1 that were responsible for the citrinin synthesis during evolution. In addition, changes in transcription factor expression may also influence the network regulating the citrinin synthesis pathway in M. purpureus. Moreover, the yields of pigments produced by the winter mutant were significantly increased. Repressing the central carbon metabolism and improving the acetyl-CoA pool can contribute to a high pigment yield, and enhanced NADPH regeneration can also lead to the metabolic flux of pigment production in M. purpureus. Investigations into the biosynthesis and regulation of citrinin and pigment production in M. purpureus will enhance our knowledge of the mechanisms behind the biosynthesis of fungal secondary metabolites.

Microparticulated whey protein-pectin complex: A texture-controllable gel for low-fat mayonnaise.

This article reports caloric value changes, stability and rheological properties of mayonnaises affected by fat mimetic based on Microparticulated whey protein (MWP) and high-methoxy pectin. Lipid was partially substituted at different levels of 20%, 40%, 60%, 80% and 100%, and the samples were referred to as FM20, FM40, FM60, FM80 and FFM, respectively. The full fat (FF) mayonnaise was used as a control experiment. For rheological properties, the addition of fat mimetic resulted in the gradual decrease of pseudoplastic behavior, relative thixotropic area and viscosity index, while elasticity index exhibited the opposite trend. After 30 days of storage, all mayonnaises except FM20 were categorized as weak gels under oscillatory tests, while FM20 displayed high storage stability. Long-term stability studies showed that the addition of the fat mimetic up to 60% could significantly enhance the storage stability of mayonnaises by preventing the coalescence and flocculation of the droplets. Both the dynamic mechanical measurement and stability study results suggested that MWP and pectin could be a potential fat mimetic used in mayonnaise.

MptriA, an Acetyltransferase Gene Involved in Pigment Biosynthesis in M. purpureus YY-1.

Monascus pigments (Mps) have been used as food colorants for several centuries in Asian countries. MptriA is a putative acetyltransferase gene involved in the MPs biosynthesis. To analyze the function of MptriA, an MptriA disruption strain (Δ MptriA) and a complementation strain (Δ MptriA:: MptriA) were successfully obtained In addition to the loss of color, the disruption of MptriA had little effect on the phenotypes during growth on four different media. The Δ MptriA strain showed decreased pigment and citrinin production during the liquid-fermentation process. Transcriptional analysis showed that the expression of several genes involved in the synthesis of pigments and citrinin was down-regulated in Δ MptriA. These results demonstrated that the role of MptriA was to transfer an acyl group to the pyranoquinone structure of the polyketide chromophore during Monascus pigment biosynthesis and to influence the citrinin biosynthesis pathway. This study contributes to the exploration of pigment biosynthesis in M. purpureus.

Orf6 gene encoded glyoxalase involved in mycotoxin citrinin biosynthesis in Monascus purpureus YY-1.

As traditional edible fungi, Monascus spp. have been widely used as folk medicine, food colorants, and fermentation starters in East Asian countries for more than a thousand years. However, the presence of citrinin, which has nephrotoxic, hepatotoxic, and carcinogenic activities, raises suspicions about the safety of Monascus products. Citrinin biosynthesis in Monascus is known to occur via a polyketide pathway and a citrinin biosynthesis gene cluster, which include the characterized polyketide synthetase pksCT. A gene, orf6, encodes a protein that shows significant similarity to glyoxalase and is located between ctnE and orf1. This study analyzed orf6 function, and successfully obtained an orf6 disruption strain (Δorf6). Citrinin production was significantly greater (3.6-fold) in the Δorf6 strain than in the wild-type Monascus purpureus YY-1, and RT-PCR analysis further revealed increased expression of numerous genes of the citrinin biosynthesis gene cluster in Δorf6. Therefore, orf6 proved to be a major inhibitor, directly involved in citrinin biosynthesis. Moreover, pigment production in Δorf6 was reduced by approximately 30%, while the transcription levels of many genes involved in Monascus pigments (MPs) biosynthesis had increased. This dichotomy indicated that MPs and citrinin yields may be improved simultaneously; however, a portion of the pigments was consumed to protect the cells from oxidative damage in the Δorf6 strain. An Δorf6 revertant restored the citrinin and pigment yields to normal levels. This study makes a contribution to explore the citrinin biosynthesis pathway and provides some theoretical guidance to improving the safety of Monascus-related products.