Improving the water solubility of Monascus pigments under acidic conditions with gum arabic

Effect of pretreatment with electron beam irradiation on the deacetylation efficiency of konjac glucomannan and its structural, physicochemical and gel properties

Due to its emulsifying and thickening properties, konjac glucomannan (KGM) is widely used in the food, medicine, and materials industries. Nevertheless, its high viscosity and significant water absorption limit its application range. Therefore, electron beam (e-beam) irradiation pretreatment was carried out to improve the deacetylation efficiency of KGM, and the physicochemical and gel properties of KGM were investigated. The results show that e-beam irradiation and deacetylation decrease the water absorption, solubility, transparency, molecular weight, and viscosity of KGM. Conversely, the moisture content, thermal stability, and water-binding capacity increase. FTIR and X-ray diffraction analysis revealed no significant changes in the chemical and crystalline structure of KGM before and after modification. However, modification weakens the intermolecular interaction of KGM hydrosols, which affects their rheology. Furthermore, deacetylation improves the mechanical properties and water retention capacity of KGM gels. Overall, the e-beam irradiation pretreatment provides a method to increase the efficiency of KGM deacetylation and improve the physical and chemical properties of KGM, thus expanding its potential applications in the food and chemical industries, among others.

Microencapsulation of highly concentrated polyphenolic compounds from purple corn pericarp by spray-drying with various biomacromolecules

Colored corn pericarp contains unusually high amounts of industrially valuable phytochemicals, such as anthocyanins, flavanols, flavonoids, and phenolic acids. Polyphenols were extracted in an aqueous solution and spray-dried to produce microencapsulates using four carrier materials, namely, maltodextrin (MD), gum arabic (GA), methylcellulose (MC), and skim milk powder (SMP) at three concentrations (1, 2, and 3 %, respectively). The encapsulates were evaluated for their polyphenolic contents using spectrophotometric techniques and HPLC analyses, and their antioxidant properties were evaluated using four different assays. The physicochemical properties of encapsulates were analyzed by measuring the zeta potential (ZP), particle size distribution, water solubility index (WSI), water absorption index (WAI), and color parameters. Structural and thermal properties were evaluated using Fourier transform infrared spectroscopy (FTIR), optical profilometry, and differential scanning calorimetry (DSC) analyses. Comparative analysis of structural characteristics, particle size distribution, zeta potential, WSI, WAI, and aw of the samples confirmed the successful formulation of encapsulates. The microencapsulates embedded with 1 % concentrations of MD, MC, GA, or SMP retained polyphenolic compounds and exhibited noteworthy antioxidant properties. The samples encapsulated with GA or MD (1 %) demonstrated superior physicochemical, color, and thermal properties. Comprehensive metabolomic analysis confirmed the presence of 38 phytochemicals in extracts validating the spray-drying process.

Preparation of Hybrid Nanopigments with Excellent Environmental Stability, Antibacterial and Antioxidant Properties Based on Monascus Red and Sepiolite by One-Step Grinding Process

This study is focused on the preparation, characterization, and multifunctional properties of intelligent hybrid nanopigments. The hybrid nanopigments with excellent environmental stability and antibacterial and antioxidant properties were fabricated based on natural Monascus red, surfactant, and sepiolite via a facile one-step grinding process. The density functional theory calculations demonstrated that the surfactants loaded on sepiolite were in favor of enhancing the electrostatic, coordination, and hydrogen bonding interactions between Monascus red and sepiolite. Thus, the obtained hybrid nanopigments exhibited excellent antibacterial and antioxidant properties, with an inhibition effect on Gram-positive bacteria that was superior to that of Gram-negative bacteria. In addition, the scavenging activity on DPPH and hydroxyl free radicals as well as the reducing power of hybrid nanopigments were higher than those of hybrid nanopigments prepared without the addition of the surfactant. Inspired by nature, gas-sensitive reversible alochroic superamphiphobic coatings with excellent thermal and chemical stability were successfully designed by combining hybrid nanopigments and fluorinated polysiloxane. Therefore, intelligent multifunctional hybrid nanopigments have great application foreground in related fields.

A novel edible colorant lake prepared with CaCO3 and Monascus pigments: Lake characterization and mechanism study

Monascus pigments (MPs) were adsorbed using calcium carbonate to produce CaCO₃-MPs lakes. The fundamental properties and formation mechanism of the lakes were investigated. Results indicated that CaCO₃ displayed a high enough affinity for the MPs to form colorant lakes, while the MPs tended to transform the CaCO₃ crystals from calcite to vaterite. The adsorption of MPs by CaCO₃ followed the Freundlich isothermal model with n value higher than 1, confirming it as physical adsorption. The ΔG⁰ (-29 to ∼-33 kJ/mol) and ΔH⁰(30-55 kJ/mol) indicated that lake formation was a spontaneous and endothermic process. UV/Vis spectroscopic analysis verified the complex formation between Ca²⁺ and MPs via physical bonding, suggesting a possible attraction between the Ca²⁺ and glutamate residues of the MPs. EDS showed that the MPs were trapped inside the particles. FTIR spectroscopy and XPS further confirmed that the physical bonding was the primary driving force behind the lake formation.

Preparation, Multispectroscopic Characterization, and Stability Analysis of Monascus Red Pigments-Whey Protein Isolate Complex

Monascus red pigments (MRPs) are mainly used as natural food colorants; however, their application is limited due to their poor stability. To expand their areas of application, we investigated the binding constants and capacity of MRPs to whey protein isolate (WPI) and whey protein hydrolysate (WPH) and calculated the surface hydrophobicities of WPI and WPH. MRPs were combined with WPI and WPH at a hydrolysis degree (DH) of 0.5% to form the complexes (DH = 0.0%) and (DH = 0.5%), respectively. Subsequently, the structural characteristics of complex (DH = 0.5%) and WPI were characterized and the color retention rates of both complexes and MRPs were investigated under different pretreatment conditions. The results showed that the maximum binding constant of WPI with MRPs was 0.670 ± 0.06 U^-1 and the maximum binding capacity was 180 U/g. Furthermore, the thermal degradation of complex (DH = 0.0%), complex (DH = 0.5%), and MRPs in a water bath at 50-100 °C followed a first-order kinetic model. Thus, the interaction of WPI with MRPs could alter the protein conformation of WPI and effectively protect the stability of MRPs.

Binding of ankaflavin with bovine serum albumin (BSA) in the presence of carrageenan and protective effects of Monascus yellow pigments against oxidative damage to BSA after forming a complex with carrageenan

Ankaflavin (AK) is a typical yellow pigment extracted from Monascus-fermented rice with several biological effects; however, its solubility is poor. Thus, research studies of the delivery systems of AK, especially those constructed from protein-polysaccharide complexes, have attracted considerable attention. However, the interactions that exist in the system have rarely been investigated. This work focused on the interactions between AK and bovine serum albumin (BSA) as well as the influence of carrageenan (Car) on the binding of AK to BSA. Results revealed that the quenching of BSA by AK involved the static quenching mechanism. The formed BSA-AK complexes were mainly maintained by hydrophobic forces and AK was located within the hydrophobic cavity of BSA. Compared to free AK or AK only complexed with BSA, a higher absorption intensity of AK was observed for the formed BSA-AK-Car complexes, indicating changes in the microenvironment of AK. This was confirmed by the increase in the α-helix content of BSA after the formation of BSA-AK-Car complexes. Hydrogen bond, van der Waals, and electrostatic interactions were verified to be the primary forces preserving the BSA-AK-Car complexes. Moreover, the antioxidant potential of Monascus-fermented products rich in AK (denoted as Mps), namely BSA-Mps and BSA-Mps-Car was evaluated. The antioxidant activity of Mps was negatively impacted by BSA, while the addition of Car could enhance the antioxidant capacity of BSA-Mps-Car complexes. Meanwhile, Mps showed a protective effect against free radical-induced oxidation damage to BSA, and Car could further improve this effect.

Sodium starch octenyl succinate facilitated the production of water-soluble yellow pigments in Monascus ruber fermentation

Natural water-soluble Monascus pigments (WSMPs) have been in increasing demand but have not been able to achieve industrial production due to the low production rate. This study aimed to improve the biosynthesis and secretion of extracellular yellow pigments (EYPs) through submerged fermentation with Monascus ruber CGMCC 10,910 supplemented with sodium starch octenyl succinate (OSA-SNa). The results demonstrated that the yield was 69.68% and 48.89% higher than that without OSA-SNa in conventional fermentation (CF) and extractive fermentation (EF), respectively. The mainly increased EYP components were Y3 and Y4 in CF, but they were mainly Y1 and Y2 as well as secreted intracellular pigments, including Y5, Y6, O1, and O2, in EF. Scanning electron microscopy analysis revealed that the mycelium presented an uneven surface profile with obvious wrinkles and small fragments with OSA-SNa. It was found that a higher unsaturated/saturated fatty acids ratio in the cell membrane resulted in increased permeability and facilitated the export of intracellular yellow pigments into the broth with OSA-SNa treatment. In addition, a higher NAD⁺/NADH ratio and glucose-6-phosphate dehydrogenase activity provided a reducing condition for yellow pigment biosynthesis. Gene expression analysis showed that the expression levels of the key genes for yellow pigment biosynthesis were significantly upregulated by OSA-SNa. This study provides an effective strategy to promote the production of WSMPs by microparticle-enhanced cultivation using OSA-SNa. KEY POINTS: • OSA-SNa addition facilitated the production of Monascus yellow pigments. • Mycelial morphology and membrane permeability were affected by OSA-SNa. • The key gene expression of yellow pigments was upregulated.

The Stability, Microstructure, and Microrheological Properties of Monascus Pigment Double Emulsions Stabilized by Polyglycerol Polyricinoleate and Soybean Protein Isolate

Monascus pigment is a natural food pigment and is commonly used for coloring and as antiseptic of cured meat products, confectionery, cakes, and beverages. However, Monascus pigment is sensitive to environmental conditions. The main aim of this study was to investigate the effect of polyglycerol polyricinoleate (PGPR) and soy protein isolate (SPI) on the particle size, zeta potential, physical stability, microstructure, and microrheological properties of Monascus pigment double emulsions. The effects of ionic strength, heating, and freeze thawing treatment on the stabilities of Monascus pigment double emulsions were also characterized. It was found that the optimum PGPR and SPI concentrations for fabricating Monascus pigment double emulsion were 3.6 and 3.0 wt%, respectively. The fabricated Monascus pigment double emulsion was composed of fine particles with narrow and uniform size distributions. Microrheological property results suggested that the elastic characteristic of the Monascus pigment double emulsion was dominated with increasing PGPR and SPI contents. It was mainly due to the increased collision and interaction between the droplets during the movement resulting in force increasing. Monascus pigment double emulsions with <5 mM CaCl2 prevented calcium to destroy the physical stability of emulsions, while Monascus pigment double emulsions with more than 10 mM CaCl2 formed creaming. After freeze thawing treatment, creaming occurred in Monascus pigment double emulsion. However, it was stable against heating treatment due to heating leading to a dense network structure. It could be contributed to the practical applications of Monascus pigment double emulsions in food products.

Prevention of loperamide induced constipation in mice by KGM and the mechanisms of different gastrointestinal tract microbiota regulation

Constipation is one of the most prevalent gastrointestinal tract diseases. Konjac glucomannan (KGM) dietotherapy can effectively relieve the clinical symptoms of patients with constipation. However, the causal relationship among KGM, constipation and different gastrointestinal microbiome (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) remains poorly understood. In this study, constipated mice were treated with KGM (75, 150, 300 mg/kg bw). Results showed that KGM treatment improved the general physiological state, fecal character, small intestinal propulsive rate, gastric emptying rate, MTL and AchE activities, ET-1, 5-HT, and NO levels, and SCFA concentrations. KGM in the diets of constipated mice reduced the diversity of St and S microbiota, while increased those in the L. The KGM intervention regulated the microbiota profile, which afterwards was closer to the normal mouse group: confirmation was provided by different changes of bacteria like Lactobacillus, Bifidobacterium and Allobaculum spp et al.

Encapsulation of vitamin D3 in gum arabic to enhance bioavailability and stability for beverage applications

Delivery of vitamin D₃ (VD₃ ) in foods should exhibit desirable physicochemical characteristics and improves absorption. In this study, gum arabic (GA) was investigated as a VD₃ carrier to encapsulate VD₃ . VD₃ dissolved in 5 mL ethanol corresponding to 0.3 to 6.0% mass of GA, was blended in 5.0% w/v GA solution, followed by freeze drying. The encapsulation efficiency decreased while loading capacity increased with an increased amount of VD₃ . At the highest VD₃ level, the loading capacity (3.47%) was the highest, and the encapsulation efficiency (61.24%) was satisfactory, and the treatment was further studied. The magnitude of negative zeta-potential increased from 3.1 to 31.0 mV at pH 2.0 to 7.4. During the 100-day storage at 3 °C of capsules reconstituted at pH 2.0 to 7.4, the hydrodynamic diameter decreased at all pH conditions, most evident for reduction to 81.3 nm at pH 7.4, and no precipitation was observed, indicating the significance of steric repulsion on capsule stability. Bioaccessibility of VD₃ in capsules (95.76%) was significantly higher than the nonencapsulated VD₃ (68.98%). The in vivo pharmacokinetic study in Sprague-Dawley rats after a single-dose of 300 µg VD₃ showed the area-under-curve of serum 25(OHD) level in 48 hr of the encapsulation treatment was 4.32-fold of the nonencapsulated VD₃ and more than twice higher than the VD₃ -GA physical mixture. During 2-week supplementation of 60 µg VD₃ /d, rats receiving capsules or physical mixture had 25(OH)D levels of at least 81 ng/mL higher than that of the nonencapsulated VD₃ group. The studied encapsulation system holds great potential as a value-added ingredient to supplement VD₃ in beverages with a wide pH range. PRACTICAL APPLICATION: The findings of this study demonstrated the improved dispersion stability and absorption of vitamin D₃ after encapsulation in gum arabic. The capsules exhibited good dispersion stability across a pH range between 2.0 and 7.4, showing potential application in beverages. Furthermore, the enhanced absorption of VD₃ after encapsulation highlights the nutritional benefits of the studied encapsulation system.

Quantitative insight into dispersity and antibactericidal capability of silver nanoparticles noncovalently conjugated by polysaccharide-protein complexes

Precise prediction and measurement of dispersibility of silver nanoparticles (AgNPs) under atmospheric conditions are extremely vital for their potential commercial application. In the present work, the dispersibility of AgNPs capped by polysaccharide-protein from viscera of abalone (PSP-AgNPs) was studied using the combination of ultraviolet-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and multiple-light-scattering (MLS) techniques. The results showed that the combination of UV/vis, DLS and MLS not only accurately determined the dispersibility of PSP-AgNPs, but also provided detailed information about the aggregation behavior of PSP-AgNPs. Furthermore, the results revealed a high dispersibility of PSP-AgNPs in the studied environment. The system temperature, pH value and thermal treatment (pasteurization and sterilization) had no effect on the dispersion of PSP-AgNPs in the effective concentration range against the pathogenic bacteria. Besides, an excellent stable dispersion and antibacterial activity against common pathogenic vibrio was also found in the dispersed PSP-AgNPs in seawater. Overall, the study provides a suitable method for the precise measurement of the dispersibility of AgNPs in environment. The AgNPs act as a potential bactericide with good dispersion and antibacterial activity in mariculture and other fields.