Stability Of Pigments Research Articles

An intelligent indicating label using mulberry pigment, polylactic acid and rutile TiO2 nanoparticle for monitoring the freshness of cold fresh pork

The purpose of this work is to develop a new type of intelligent indicating label with high sensitivity to volatile bioamine, anti-ultraviolet light and anti-pigment leakage characteristics by electrospinning for real-time visual monitoring the freshness of cold fresh pork. By investigating pH discoloration sensitivity and light stability of plant pigments with different structures, mulberry pigment was selected as the indicator of indicating label. The content of label components (mulberry pigment, polylactic acid and TiO2 nanoparticle) significantly affected label performance (light stability, responsiveness to trimethylamine, and anti-leakage of mulberry pigment), and the optimal component content was determined to be 6.01% (w/w) of polylactic acid, 0.62% (w/w) of TiO2 nanoparticles and 0.29% (w/w) of mulberry pigment by response surface test based on label performance as response value. A close correlation (the correlation coefficient R values of 0.86–0.97) between the total color difference (ΔE) of the label and the freshness indexes (total plate count, total volatile basic nitrogen content, pH, thiobarbituric acid value and sensory score) of cold fresh pork during cold storage was revealed, and the freshness level of unknown pork samples could be well quantitatively predicted by partial least squares regression models with the determination coefficient (R2) values of 0.89–0.92, facilitating producers, dealers and consumers to know pork quality promptly.

Sebacate intercalated Ca[sbnd]Al layered double hydroxide pigments for corrosion protection of low carbon steel: Anion exchange and electrochemical properties

Sebacate (SB) molecules were incorporated into CaAl layered double hydroxides (CaAL-LDH) using a hydrothermal method. The resulting products underwent characterization through X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. To investigate the release kinetics and thermodynamics of the corrosion inhibitor, total organic carbon analysis (TOC) was employed. A comparison was made with CaAl-LDH prepared without corrosion inhibitors, in which nitrates were the primary anions within the layered clay structure. An assessment of anion exchange between nitrates and chlorides was conducted using total nitrogen analysis (TN). The SB anion comprised approximately 49.2% of the total dried powder synthesized, with a maximum release efficiency of around 86.7% fitting a Langmuir model. For the evaluation of the corrosion inhibition effect on steel surfaces, electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning vibrating electrode technique were employed. The corrosion inhibition impact was ascribed to the liberation of SB anions from the CaAl-LDH pigments, accompanied by alkalinization stemming from partial particle dissolution. Additionally, the incorporation of organic molecules notably enhanced the stability of pigments in aqueous solutions compared to similar ones hosting nitrates. These findings suggested that CaAl-LDH pigments have potential as nanocontainers for organic inhibitors, showing promising prospects in the field of corrosion research.

Ameliorating heat stressed conditions in wheat by altering its physiological and phenotypic traits associated with varying nitrogen levels

Currently, more than half of the global nations cultivating wheat crops are facing severe consequences of climate change and its associated heat stress in terms of quantitative and qualitative yield losses. Plants exposed to heat stress need a balanced and adequate amount of mineral nutrients to counter its ill effects. Therefore, the present study was designed to investigate the potential effects of heat stress applied during the vegetative growth period (Zadoks growth scale: ZGS 5-60) on physiological and phenotypic traits of wheat (Triticum aestivum) crop subjected to variable rates of nitrogen (N). In this experiment, wheat plants of cv. ‘Punjab-2011’ were exposed to two levels of temperature i.e. heat stress (HS) and control or non-heat stress (NHS), and three N rates (N50 = 50 kg ha-1, N100= 100 kg ha-1 and N150 = 150 kg ha-1). The experiment was executed under controlled conditions in a completely randomized design (CRD) with six replications. One set of eighteen pots containing wheat seedlings was placed in a compartment of the greenhouse under heat-stressed conditions, while another set was placed in another compartment under non-heated conditions. The greenhouse compartments were equipped with a heating and cooling system to maintain desired ecological conditions. Pots in heated chamber were kept for 60 days from emergence (ZGS = 5-60), and then shifted to non-heated chamber till harvesting. The temperature in heat stress treatment was almost 2 ± 0.47 °C higher than in non-heated treatment. The results indicated that HS significantly reduced the photosynthetic rate by 42.52%, leaf photosynthetic efficiency by 56.82%, chlorophyll scores by 20.11%, relative water contents (RWC) by 12.81%, tillers by 48.21%, grain weight by 21.47% and grain yield by 68.20% relative to NHS conditions. These reductions were more prominent in plants subjected to a limited N dose rate (50 kg N ha-1). Furthermore, the results also revealed higher transpiration rate, stomatal conductance, and membrane ruptures under HS with N50 treatment. However, N150 treatment compensated for the detrimental effects of HS on wheat plants by improving the photosynthetic rate and efficiencies, higher RWC, more stability of membrane and pigments, more tillers, and higher grain weight, and grain yield of wheat. Additionally, grain yield was negatively correlated with transpiration rate, stomatal conductance, internal CO2 concentration, and membrane leakage. In conclusion, a high dose rate of N under high temperatures during vegetative growth could alleviate the magnitude of penalties to grain yield and enhance the potential of wheat crops to withstand heat-induced detrimental effects.

Synthesis of Periclase Phase (MgO) from Colloidal Cassava Starch Suspension, Dual Application: Cr(III) Removal and Pigment Reuse

Synthesis of Periclase Phase (MgO) from Colloidal Cassava Starch Suspension, Dual Application: Cr(III) Removal and Pigment Reuse

APPLICATION OF LAKES SYSTEM IN PREPARATION OF HAIR DYES POMADE CREAM OF FREEZE-DRIED RED DRAGON (Hylocereus polyrhizus) FRUIT PEEL JUICE AND ACUTE DERMAL IRRITATION

Dyes used in market products are mostly synthetic, which can irritate the skin and in the long term increase the risk of skin cancer. The peel of dragon fruit contains the red-violet pigment Betacyanin, which is potential as hair dyes but extremely sensitive to light and oxygen. The lakes system is the option to overcome the problem and increase the stability of pigments. The objective of this study was to learn about the use of the lakes system in the preparation of hair dyes pomade cream of freeze-dried red dragon fruit peel juice and its irritation aspect on skin. The lakes system was made with a 50% red dragon fruit peel juice, mixed with 5% alucol, then dried with 45% aerosil. Pomade cream was prepared by mixing oil phase and water phase at a temperature of ±60 °C with continuous mixing in 600 rpm for 10 minutes. Formula III is the bases without freeze-dried red dragon fruit peel juice. The non-lakes system of freeze-dried red dragon fruit peel juice was added to the bases for the FII, while the lakes system was added for the FI. Hair dyes pomade cream of red dragon fruit peel juice prepared in the lakes system has superior properties to the formula prepared without the lakes system. It demonstrated better homogeneity and softer texture, in addition acceptable skin pH range. The lakes system is suitable for the preparation of natural hair dye cream and does not irritate the skin.

A critical review on the stability of natural food pigments and stabilization techniques

This comprehensive review article delves into the complex world of natural edible pigments, with a primary focus on their stability and the factors that influence them. The study primarily explores four classes of pigments: anthocyanins, betalains, chlorophylls and carotenoids by investigating both their intrinsic and extrinsic stability factors. The review examines factors affecting the stability of anthocyanins which act as intrinsic factors like their structure, intermolecular and intramolecular interactions, copigmentation, and self-association as well as extrinsic factors such as temperature, light exposure, metal ions, and enzymatic activities. The scrutiny extends to betalains which are nitrogen-based pigments, and delves into intrinsic factors like chemical composition and glycosylation, as well as extrinsic factors like temperature, light exposure, and oxygen levels affecting for their stability. Carotenoids are analyzed concerning their intrinsic and extrinsic stability factors. The article emphasizes the role of chemical structure, isomerization, and copigmentation as intrinsic factors and discusses how light, temperature, oxygen, and moisture levels influence carotenoid stability. The impacts of food processing methods on carotenoid preservation are explored by offering guidance on maximizing retention and nutritional value. Chlorophyll is examined for its sensitivity to external factors like light, temperature, oxygen exposure, pH, metal ions, enzymatic actions, and the food matrix composition. In conclusion, this review article provides a comprehensive exploration of the stability of natural edible pigments, highlighting the intricate interplay of intrinsic and extrinsic factors. In addition, it is important to note that all the references cited in this review article are within the past five years, ensuring the most up-to-date and relevant sources have been considered in the analysis.

Agricultural waste Ipomoea batatas leaves for low-temperature dyeing and functional finishing of polyester fabrics

The increasing focus on eco-friendly textiles and cleaner production manufacturing techniques have made natural pigments for coloring and enhancing the functionality of textiles become a popular trend. This research aimed to extract plant pigment from bio-waste Ipomoea batatas leaves and utilize it for dyeing and functional decoration of polyester fabric at low temperature. The study optimized the parameters for pigment extraction and fabric dyeing and also investigated the stability of the pigment solution. The finding indicated that strong acids and bases, intense light, high temperatures, and oxidants have a greater impact on pigment stability. Observation and analysis using SEM, bio-optical microscope, FTIR, and UV–vis–NIR absorption spectroscopy revealed that chlorophyll pigment entered into the interior of polyester molecular chains through hydrophobic end intercalation and was retained by the physical forces, enabling low-temperature coloring and functional finishing of polyester fabrics. As a result, the polyester fabrics dyed with natural pigment exhibited excellent resistance to rubbing, washing, saliva, and perspiration (rated at level 4 or higher), except for the average light fastness (only grade 4). Additionally, the dyed polyester fabrics demonstrated outstanding UV resistance (UPF of 33.57 for raw polyester and 120.77 for pre-mordant dyed polyester) and antibacterial properties (raw polyester agar plates showed bacterial growth, while the colored polyester agar plates had almost no bacterial growth). Even after 10 wash cycles, the dyed polyester fabrics maintained their UV protection and antibacterial properties. This research is expected to provide a new approach to the valuable utilization of agricultural residues in the textile industry.

BaO, ZnO, B2O3, PbO, and SiC effects on phosphorescent afterglow damping and thermal stability of SrAl2O4 base pigments at industrial glazes

Phosphorescent glazes are usually used in direction signs of emergency routes. That is why afterglow damping and thermal stability of phosphorescent pigments are the most decisive factors of phosphorescent glazes. This study aims to choose a suitable glaze to enhance the time and intensity of the afterglow. For this reason, the effects of BaO, ZnO, B2O3, and PbO additives on the afterglow intensity and lifetime of reference industrial glaze containing SrAl2O4 phosphorescent material were investigated. 5, 7, 10, 15, and 20 %wt SrAl2O4 phosphorescence powder was mixed with base industrial glaze to recognize the optimum component. Samples were fired at 1040 °C for 40 min in the same conditions and then were analyzed by photoluminescence spectroscopy. Results showed that increasing the SrAl2O4 proportion increased samples afterglow damping time, and 10 %wt SrAl2O4 was chosen as the optimum amount. Also, BaO is more efficient for increasing the intensity and afterglow lifetime. Moreover, 0.02, 0.03, 0.05, and 0.1 %wt SiC were added to the reference industrial glaze containing 10 %wt SrAl2O4 to investigate the reduction firing conditions on the glaze afterglow. Increasing the SiC ratio up to 0.02 %wt increased the afterglow lifetime from 5 ± 0.4 to 27 ± 1.7 min, but the afterglow intensity was decreased. Despite this, adding 0.03, 0.05, and 0.1 %wt SiC darkened the glaze and reduced the intensity and afterglow lifetime. The sample containing 0.1 %wt SiC did not melt properly, and this sample did not have any afterglow. Furthermore, the temperature required for firing affects the afterglow of the samples. On the other hand, to investigate the effect of temperature, the base industrial glaze containing 10 %wt SrAl2O4 was fired at 1040, 1120, and 1140 °C to determine thermal stability. The sample fired at 1140 °C had almost no phosphorescent afterglow. Also, dilatometry tests at the temperature of 600 °C and hot-stage microscope analysis were performed to determine the linear coefficient of thermal expansion and the melting point of the samples, respectively. The results showed the linear coefficient of thermal expansion of the industrial glaze with 10 %wt SrAl2O4 was 73.3 × 10−7 1/°C, and it could be changed between 58.5 × 10−7 1/°C by adding 10 %wt B2O3 to 73.5 × 10−7 1/°C by adding 10 %wt BaO. The melting point of the pure industrial glaze was 1130 °C, and adding 10 %wt, SrAl2O4 decreased it to 1076 °C. Also, by adding 10 %wt BaO, ZnO, B2O3, and PbO to phosphorescent glaze, melting point was obtained 1128 °C, 1020 °C, 1030 °C, and 974 °C respectively. The same sample with 0.02 %wt SiC melted at 1154 °C.

Acerola (Malpighia emarginata) pulp: characterization and stability of anthocyanins under different conditions

Tropical fruits provide a high economic potential and their inclusion in the diet can provide health benefits. In this sense, this study aimed to evaluate the proximal composition, bioactive compounds, antioxidant activity, and stability of anthocyanins of acerola pulp in the absence and presence of light at temperatures of 7 and 21.7°C. The results for the proximal composition (g/100 g) were 93.49 moisture, 0.04 protein, 0.09 lipid, 0.60 ash, and 6.28 carbohydrates, totaling a 28.29 kcal/100 g caloric value. For total bioactive compounds, the results were 3.22 µg/g chlorophyll, 29.71 µg/g carotenoids, 3.74 g/100 g flavonoids, and 6.12 mg/100 g phenolic compounds. Acerola pulp showed high antioxidant activity by DPPH and ABTS methods with values of 6.17 μmol/g and 3.19 mM TEAC/g, respectively. Regarding the stability of anthocyanins, in acerola pulp stored away from light and at a temperature of 7°C, these pigments remained more stable than when subjected to light and a temperature of 21°C. Thus, it was possible to perceive that, in addition to the acerola being important for the food industry, storage under low temperatures and the absence of light can contribute to greater stability of anthocyanin pigments.

Light stability and mechanism of monascus pigment under different lights

Application of Monascus pigments in the food industry is hindered by their vulnerability to light, yet the underlying mechanism of their light-induced fading remains unclear. In this study, Monascus pigments sourced from Monascus rice were employed to investigate their stability under distinct light treatments, including visible light, UV light, and sunlight. The research demonstrates a clear connection between the light stability of Monascus pigments and their composition. Among the various light sources, simulated sunlight emerges as the most deleterious to the red Monascus pigment, whereas UV light inflicts greater damage on the yellow Monascus pigment compared to other sources. Employing density functional theory (DFT) and time dependent DFT (TDDFT), we deduced the mechanism of Monascus pigments' photolysis by comparing EHOMO, ELUMO, △E, λmax, and Eλmax of the six original Monascus pigments. The outcomes reveal a distinct photo-stability sequence for different pigments: red Monascus pigment < orange Monascus pigment < yellow Monascus pigment. Furthermore, our study proposes electron transfer from the c = c double bond to the c-c single bond as a component of the photolysis mechanism. This research contributes theoretical and experimental evidence on the photo-stability and mechanisms governing diverse Monascus pigments under various light conditions. These insights are crucial for optimizing the integration of these pigments in the food industry, with implications for packaging and storage considerations.

Stability kinetics of orevactaene pigments produced by Epicoccum nigrum in solid-state fermentation

Abstract Orevactaene yellow pigment was produced by solid-state fermentation of broken rice using Epicoccum nigrum. The pigment was extracted using water as a solvent and subjected to stability studies at different temperatures (30, 40, 60, and 80°C), pH (4, 6, and 8), sterilization, and sunlight exposure treatment. The observed data were fitted in the first-order kinetic model. Yellow pigment stability was found to vary at different temperatures studied. At 30°C, only a 4% decrease in color intensity was observed after 2 h; at 40°C, an 8% decrease was observed, and at 80°C and pH 6.0, 17% of color intensity was lost. These results showed that the orevactaene pigment produced by E. nigrum is heat-sensitive and changes in color intensity should be expected in heat-processed products. After 180 min at 80°C, yellow pigments maintained 82 and 76% of the initial color at pH 6 and 8, while a 65% decrease in color intensity was observed at 80°C, pH 4. Autoclaving resulted in 69% decay and exposure of pigment to sunlight for 2 h showed 1% decay. The half-life period of the pigment at different temperatures varied from 82.5 to 5.25 h. The decimal reduction time decreased from 275 to 17.5 h with an increase in the temperature. Thermodynamic parameters for pigment decay at pH 6.0 were represented in terms of enthalpy ∆H, activation energy E a, free energy ∆G, and entropy ∆S. The values observed were 44.52–44.93, 48.48, 96.60–105.18 kJ/mol, and −170.50 to −171.85 J/mol/K, respectively. All these parameters help in predicting the quality changes in terms of appearance during thermal processing and optimizing the process.

Stability of pigments from Termitomyces sp. (termite mushroom), Pleurotus citrinopileatus (yellow oyster mushroom) and Pleurotus djamor (pink oyster mushroom) as natural food colouring

Food colouring has been used in food items for a long time to enhance the natural colour of food, maintain colour consistency and enhance product attractiveness. The most popular food colouring is synthetic since it is more stable and less expensive. However, there is growing concern about how artificial food colouring affects human health. As a result, research into using natural food colouring as an alternative to synthetic colouring has grown. Due to the complexity of food products, natural food colouring is unstable and prone to degradation. Therefore, the goal of this study was to use the CIELAB colorimeter to ascertain the colour stability of the pigments found in Termitomyces sp. (termite mushroom), Pleurotus citrinopileatus (yellow oyster mushroom) and Pleurotus djamor (pink oyster mushroom). At three pH levels (3.0, 7.0 and 15.0), the stability of pigments derived from these mushrooms was assessed; the pigments were most stable at pH 7.0. Additionally, the pigments were heated from 40 to 100°C. The outcomes demonstrated that P. citrinopileatus's yellow pigment was unstable at 40°C, 60°C 80°C and 100°C. When heated between 40°C and 80°C, the pigments derived from P. djamor and Termitomyces sp. remained stable. Ascorbic acid, citric acid, and sodium metabisulphite treatments had no discernible effects on the stability or colour of the pink pigment (a* values) as compared to the control.

Polystyrene microplastics enhance oxidative dissolution but suppress the aquatic acute toxicity of a commercial cadmium yellow pigment under simulated irradiation

Commercial cadmium yellow (CdS) pigment widely coexist with microplastics (MPs) in surface water, thus it is important to understand how MPs affect CdS pigment stability and toxicity under irradiation. Herein, the dissolution of CdS pigment (krelease = 0.118 h–1) under irradiation was visibly increased to 0.144 h–1 by polystyrene (PS) MPs, due to reactive species generation such as 1O2, •OH and 3PS* , while O2•− was unimportant to this process. The O2, humic acid, photoaging status of PS MPs could promote PS MPs-related CdS pigment dissolution rate by modifying reactive species generation. However, the CO32−, PO43− and alkaline condition significantly decreased the dissolution rate to 0.091, 0.053 and 0.094 h–1, respectively, through modifying free Cd2+ stability. Comparably, PS MPs-related CdS pigment dissolution was relatively slow in natural water samples (krelease = 0.075 h–1). PS MPs at environmental concentration can also promote CdS pigment dissolution and Cd2+ release, but suppress acute toxicity of CdS pigment to zebrafish larvae as increasing 10 h survival from 65% to 85% by adsorbing the Cd2+ and decreasing Cd2+ bioavailability. This study emphasized the environmental risks and human safety of CdS pigment should be carefully evaluated in the presence of PS MPs in aquatic environments.

Superstable cellulose-supported clay-based methylene blue hybrid pigment encapsulated with porous TiO2: Processing by adsorption strategy

Organic dyes have limited industrial use due to their poor stability and resistance to harsh environmental conditions. By using inorganic materials, adsorption of organic dyes can be used to synthesize a highly stable pigment material in hybrid structure. A simple, rapid and controllable method to prepare stable hybrid pigment by adsorption of methylene blue (MB) on ethyl cellulose (EC) modified montmorillonite (Mt) was investigated. The effects of different ratios of EC, initial concentration, adsorbent dosage, time and pH on the adsorption of MB on EC:Mt were investigated. MB adsorption conformed to the Langmuir isotherm (R2 = 0.99) model according to the equilibrium test results and to the pseudo-second-order kinetic model (R2 = 1.00) in the results of the time experiments. EC:Mt-MB was coated with a layer of TiO2 to increase the stability of the hybrid pigment. Thermodynamic calculations show that MB adsorption was spontaneous and endothermic. The characterizations of the synthesized composites were performed by SEM, FT-IR, XRD, UV-DRS, TGA/DTG and zeta potential analyzes. EC:Mt-MB@TiO2 pigment showed excellent chemical stability in acidic, alkaline and ethanol medium, together with UV resistance much higher than EC:Mt-MB hybrid pigment.

Terminal carboxylation of branched carbon chain contributing to acidic stability of azaphilone pigments from a new isolate of Talaromyces amestolkiae.

Red Monascus pigments, a series of natural azaphilone alkaloids, have been utilized in China as a traditional food colorant for over 1000years. However, instability under an acidic condition is its drawback. A new strain of Talaromyces amestolkiae was isolated in the present work, which produced the azaphilone talaromycorubrin and the corresponding azaphilone alkaloid (N-MSG-talaromycorubramine) exhibiting good stability even at pH below 3. The azaphilone alkaloid with acidic stability, an alternative of Chinese traditional red Monascus pigments, is potential for application as natural food colorant in acidic foods. The acidic stability of azaphilone alkaloid also benefits for direct fermentation of N-MSG-talaromycorubramine under a low pH condition. More importantly, correlation relationship between the terminal carboxylation of branched carbon chain of azaphilone and the stability of azaphilone alkaloids under an acidic condition is set up for the first time, which makes designing other acidic stable azaphilone alkaloids via genetic engineering become possible.

Sweeping-frequency ultrasonic preprocessing improves removal rate and stability of pigment removed from okra powders by different drying and sieving methods

Decolorization is a necessary step before the extraction of okra pectin, and the reapplication of removed pigment will benefit hierarchical utilization of resources. Based on sweeping-frequency ultrasonic preprocessing (SFUP), effects of drying methods (hot air drying (HD), freeze-drying (FD)), sieves (of 60, 80, and 120 mesh) on removal rate and stability of okra pigment (OPI) were investigated. Color deepening caused by the formation of enzymatic products within 1 h of OPI degradation was explained. The extracted OPI was finally applied to noodles to check its stability further. Results showed that compared with non-ultrasonic treatment, SFUP increased removal rate of OPI with the maximum value of 49.32%, and further enhanced the stability of OPI when applied to noodles. OPI through sieves of 80 mesh owned brighter color and more excellent stability, and colored noodles with OPI through SFUP and FD had a small total color difference and strong stability.

Application and stability of fungal pigments using jelly sweets as a food model system

SummaryNatural pigments have seen an increase in usage over the past decades due to their acclaimed safety and active biological properties. This is in line with the shift in consumer market preferences requiring a source replacement for synthetic colourants. Filamentous fungi are amongst the natural sources currently explored for pigment production. In this study, the heat, pH and UV light stability of fungal pigments produced by Penicillium multicolour (dark brown), P. canescens (green) and P. herquie (yellow). Talaromyces verruculosus (red) and Fusarium solani (orange) were evaluated. The antioxidant properties of the pigments as influenced by these conditions were ascertained using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay. The pigments were also applied in a jelly sweet formulation and incubated at ambient temperature for 4 weeks. It was demonstrated that the pigment extracts of P. multicolour and T. verruculosus were significantly affected by higher pH (7.0 and 9.0), where the decline in antioxidant activity was observed. As far as high temperature and UV light exposure are concerned, all the pigment extracts, with exception of P. herquie, maintained an antioxidant activity above 35%. On the other hand, the L*a*b* values showed no overall significant change for heat and UV light exposure with the exception of P. canescens across the four pH levels (3.0, 4.0, 7.0 and 9.0), where an increase in the ‐a (green index) coupled with a decline in brightness (L* index) and b* (blue index) was observed. Finally, there was no significant change in colour over the 4 weeks of incubation. In conclusion, fungal pigments are generally stable at normal storage conditions (ambient temperature and normal light) and can be suitably applied in jelly sweets.

Effect of Exogenous and Endogenous Ectoine on Monascus Development, Metabolism, and Pigment Stability.

Monascus, a key player in fermented food production, is known for generating Monascus pigments (MPs) and monacolin K (MK), possessing bioactive properties. However, the limited stability of MPs and mycotoxin citrinin (CTN) constrain the Monascus industry. Extremolytes like ectoine, derived from bacteria, exhibit cytoprotective potential. Here, we investigated the impact of ectoine on Monascus purpureus ATCC 16365, emphasizing development and secondary metabolism. Exogenous 5 mM ectoine supplementation substantially increased the yields of MPs and MK (105%-150%) and reduced CTN production. Ectoine influenced mycelial growth, spore development, and gene expression in Monascus. Remarkably, ectoine biosynthesis was achieved in Monascus, showing comparable effects to exogenous addition. Notably, endogenous ectoine effectively enhanced the stability of MPs under diverse stress conditions. Our findings propose an innovative strategy for augmenting the production and stability of bioactive compounds while reducing CTN levels, advancing the Monascus industry.

Concerns over colour durability in the nineteenth-century industrial revolution: insights from John Ruskin’s teaching collection

The numerous new pigments that gradually became available to artists during the nineteenth-century Colour Revolution were received with contrasting attitudes. The initial enthusiasm for new chromatic possibilities was soon nuanced by concerns about the stability and performance of industrial materials. This study focuses on the work of John Ruskin, the famous art critic of Victorian England, whose artistic production was as impressive as his penmanship. Archival research into nineteenth-century literature is combined with material analyses with macro-XRF, XRD and FORS on a group of watercolours by Ruskin preserved at the Ashmolean Museum to determine his attitude towards pigment stability. The results show that he was very concerned with colour durability and chose his materials carefully, using the treatise Chromatography by the chemist George Field (first edition 1835) as guidance. The material analyses also provided new insight into the composition of specific pigments, revealing the use of a hitherto unreported cobalt-based blue.

Complexation of phycocyanin with hydroxypropyl-β-cyclodextrin and its application in blue beer containing quinoa saponins as foaming agents.

With the increasing importance attached to human health, the inclusion complex (IC) of phycocyanin (PC) into hydroxypropyl-β-cyclodextrin (HP-β-CD) have been devoted to developing the use of food preservation in this study. In this experiment, the IC of PC into HP-β-CD was prepared by the freeze-drying method and characterized by OM, TEM, UV, FTIR and TG/DSC methods. The spectroscopic features were evaluated by Ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared spectroscopy (FT-IR) confirming that PC was located in the hydrophobic cavity of HP-β-CD. Consistent with the structural properties, optical microscopy (OM) and Transmission electron microscope (TEM) observed that the addition of PC subjected the IC to an aggregation state with irregular lamellar structures. Stability assessment showed that pH, heat and light tolerance of PC significantly regulated and improved due to the PC/HP-β-CD complexation. The formation of ICs was helpful to enhancing the antioxidant activity of PC. Molecular modeling suggested that the D-pyrrole ring and its associated C=C group of phycocyanin entered the HP-β-CD cavity from the wider edge. On this basis, the development of blue beer with quinoa saponins as foaming agent and ICs as colorant was explored. The addition of quinoa saponins made the foam richer and more delicate without destroying the overall taste coordination of beer. Moreover, the protective effect of HP-β-CD presents a positive impact on the stability of blue beer pigment. Hence, PC encapsulated into HP-β-CD will be an impressive approach in food-related application of PC.