Edible Pigment Research Articles

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.

Development of a serum-free medium for myoblasts long-term expansion and 3D culture for cell-based meat.

Cell-based meat technology provides an effective method to meet the demand for meat, while also posing a huge challenge to the expansion of myoblasts. It is difficult to develop serum-free medium suitable for long-term culture and large-scale expansion of myoblasts, which causes limited understanding of myoblasts expansion. Therefore, this study used C2C12 myoblasts as model cells and developed a serum-free medium for large-scale expansion of myoblasts in vitro using the Plackett-Burman design. The serum-free medium can support short-term proliferation and long-term passage of C2C12 myoblasts, while maintaining myogenic differentiation potential well, which is comparable to those of growth medium containing 10% fetal bovine serum. Based on the C2C12 myoblasts microcarriers serum-free culture system established in this study, the actual expansion folds of myoblasts can reach 43.55 folds after 7 days. Moreover, cell-based meat chunks were preliminarily prepared using glutamine transaminase and edible pigments. The research results provide reference for serum-free culture and large-scale expansion of myoblasts in vitro, laying the foundation for cell-based meat production. PRACTICAL APPLICATION: This study developed a serum-free medium suitable for long-term passage of myoblasts and established a microcarrier serum-free culture system for myoblasts, which is expected to solve the problem of serum-free culture and large-scale expansion of myoblasts in cell culture meat production.

Optimization of Color Fractionation of Monascus Pigment

Monascus fungi are unique among the various microorganisms that produce edible pigments, which consist of red, orange and yellow. These pigments are typically present in a mixture. Hence, pigment separation is needed. This study aims to optimize solvent systems that can effectively fractionate the pigments. The optimization was carried out using column chromatography and the data was analyzed using Central Composite Design (CCD). The interaction of the solvent systems ethyl acetate : formic acid : acetic acid : water was optimized. The optimal solvent system obtained was 98 : 14 : 12 : 28 (vol/vol.) for ethyl acetate : formic acid : acetic acid : water, respectively. The red and yellow pigment obtained were 2.42 mg and 0.93 mg, respectively. Based on the finding, 72.2% of the Monascus pigments was red while remaining was yellow.

Utilization of self-assembled soy protein nanoparticles as carriers for natural pigments: Examining non-interaction mechanisms and stability

In this study, we made self-assembled soy protein nanoparticles (SPN) by partially hydrolyzing soy protein isolate (SPI) using Flavourzyme at different hydrolysis times (0, 0.5, 1, 1.5, 2, 3, and 4 h). Compared with SPI, SPN (hydrolysis time, 1.5 h) was spherical with smaller particle size, better dispersion, and higher surface hydrophobicity. The interaction and stability of SPN loaded with different concentrations (0, 0.05, 0.1, 0.3, and 0.5 mmol/L) of lutein (Lut), β-carotene (β-Car), and curcumin (Cur) were then characterized. The encapsulation efficiency, load capacity, and X-ray diffraction measurements showed that natural pigments were successfully encapsulated by SPN in amorphous form, with the highest encapsulation efficiency observed at 0.05 mmol/L with 94.3%, 88.7%, and 96.0% for Lut, β-Car, and Cur, respectively. Fluorescence, ultraviolet, and infrared spectroscopy revealed that natural pigments were loaded into SPN mainly by hydrophobic interactions, and hydrogen bonding was also involved in the loading process of Lut and Cur. Moreover, the outcomes of the isothermal titration calorimetry measurement validated the spontaneous and entropy-driven binding process between SPN and natural pigments. Due to its low molecular weight, a high number of phenolic hydroxyl groups, and low spatial resistance, Cur was most encapsulated in SPN, while the strongest interactions were observed. Lut, β-Car, and Cur were encapsulated by SPN with significantly better thermal and light stability, especially Cur. This study may open a new avenue for the use of SPN as product formulations to extend lipophilic natural edible pigments in food products.

Selective production, relationship and controversy between Monascus pigments and citrinin

Monascus pigments (MPs) are a series of high-quality natural edible pigments produced by Monascus spp. , which possess a variety of biological functions such as antioxidation, antibacterial, regulating cholesterol, anti-inflammatory, anti-cancer and antitumor. MPs have been widely used in food, medicine, cosmetics, chemical and dyes industries as functionally active ingredients. However, a mycotoxin named citrinin produced by some strains of Monascus restricts the application of MPs. It is proposed that there was a confusing relationship between the biosynthesis of MPs and citrinin. Therefore, a comprehensive understanding of the relationship can be used to develop strategies aimed at a selective production of MPs. In the present review, the discovery of MPs and citrinin, and common-used strategies for regulating their production are sorted. The possible links and controversies on synthetic pathways and productions between MPs and citrinin are also proposed and discussed. We hope this review contributes to a comprehensive understanding of the relationship between the biosynthesis of MPs and citrinin.

Histone deacetylase MrHos3 negatively regulates the production of citrinin and pigments in Monascus ruber.

Monascus spp. can produce a variety of beneficial metabolites widely used in food and pharmaceutical industries. However, some Monascus species contain the complete gene cluster responsible for citrinin biosynthesis, which raises our concerns about the safety of their fermented products. In this study, the gene Mrhos3, encoding histone deacetylase (HDAC), was deleted to evaluate its effects on the production of mycotoxin (citrinin) and the edible pigments as well as the developmental process of Monascus ruber M7. The results showed that absence of Mrhos3 caused an enhancement of citrinin content by 105.1%, 82.4%, 111.9%, and 95.7% at the 5th, 7th, 9th, and 11th day, respectively. Furthermore, deletion of Mrhos3 increased the relative expression of citrinin biosynthetic pathway genes including pksCT, mrl1, mrl2, mrl4, mrl6, and mrl7. In addition, deletion of Mrhos3 led to an increase in total pigment content and six classic pigment components. Western blot results revealed that deletion of Mrhos3 could significantly elevate the acetylation level of H3K9, H4K12, H3K18, and total protein. This study provides an important insight into the effects of hos3 gene on the secondary metabolites production in filamentous fungi.

Procyanidin B2: A promising multi-functional food-derived pigment for human diseases

Natural edible pigments play a paramount part in the food industry. Procyanidin B2 (PB2), one of the most representative naturally occurring edible pigments, is usually isolated from the seeds, fruits, and leaves of lots of common plants, such as grapes, Hawthorn, black soybean, as well as blueberry, and functions as a food additive in daily life. Notably, PB2 has numerous bioactivities and possesses the potential to treat/prevent a wide range of human diseases, such as diabetes mellitus, diabetic complications, atherosclerosis, and non-alcoholic fatty liver disease, and the underlying mechanisms were partially elucidated, including mediating signaling pathways like NF-κB, MAPK, PI3K/Akt, apoptotic axis, and Nrf-2/HO-1. This paper presents a review of the natural sources, bioactivities, and the therapeutic/preventive potential of PB2 and the possible mechanisms, with the aim of promoting the development of PB2 as a functional food and providing references for its clinical application in the treatment of diseases.

Exploiting the Thermotropic Behavior of Hydroxypropyl Cellulose to Produce Edible Photonic Pigments

AbstractHydroxypropyl cellulose (HPC) is a widely commercialized cellulose derivative. While it is typically used as a binder or stabilizer for foods and pharmaceuticals, it can also form a cholesteric liquid crystal in aqueous solution. Moreover, at high HPC concentrations this lyotropic and thermotropic mesophase is known to reflect structural color. However, it remains a challenge to retain this vibrant coloration into the solid state. Herein, by combining the emulsification of a HPC mesophase with drying at elevated temperature, solid microparticles are produced that can reflect color across the visible spectrum, from blue to green and red. This method provides a facile and scalable pathway to fabricate structurally colored, edible pigments, which can displace existing synthetic additives used in a wide range of foods and cosmetics.

A Zn(II)(2)Cys(6) transcription factor MPsGeI suppresses pigment biosynthesis in Monascus

High-quality natural edible pigments known as monascus pigments (MPs) are widely used in food, medicine, and chemical industries as active functional ingredients. At the transcriptional level, the expression of MPs genes are tightly controlled, limiting their productivity and color value. Hitherto our understanding of the regulation of expression of MPs genes has been rather limited. Here, we describe a pathway-specific Zn(II)(2)Cys(6) transcription factor involved in the MPs biosynthetic cluster named MPsGeI, which encodes a 813-amino-acid protein with six introns. Expression of all MPs biosynthetic genes and accumulation of MPs were remarkably increased in ΔMPsGeI strain, and MPs production was significantly reduced in MPsGeI over-expressing strain. Results clearly demonstrated that MPsGeI negatively regulates MPs accumulation via transcriptional regulation of MPs biosynthetic genes, and plays a central repressive role in MPs' biosynthesis. Transcriptomic analyses revealed that MPsGeI disruptant regulated higher concentrations of precursors flowing to pigment and resulted in accumulation of a large amount of red MPs in hyphae. This work offers an efficient method for increasing MPs's productivity and color value and provides novel insights into the regulatory mechanisms of fungal cellular processes, which will assist to enhance MPs production and application.

Targeted Discovery of Sorbicillinoid Pigments with Anti-Inflammatory Activity from the Sponge-Derived Fungus Stagonospora sp. SYSU-MS7888 Using the PMG Strategy.

An effective identification and discovery of fungal pigments is very important to illustrate the role of fungal pigments in the life process and conduce to the discovery of new bioactive and edible pigments. The phenotype combined with metabolomic and genomic (PMG) strategy led to the discovery and characterization of three new sorbicillinoid pigments, stasorbicillinoids A-C (1-3), and five known analogues (4-8) from the sponge-derived fungus Stagonospora sp. SYSU-MS7888. Their structures were elucidated by the application of spectroscopic methods (NMR, MS, UV, IR, and ECD) and modified Mosher's method. Compounds 1 and 2 featured novel naphthone nuclei linked by two alkyl side chains possibly undergoing inter- and intramolecular Michael reactions. Compounds 1-8 exhibited potent anti-inflammatory activity with IC50 values in the range of 3.56-22.8 μM. Furthermore, compound 2 inhibited the production of IL-1β, IL-6, and TNF-α in a dose-dependent manner. This study provides an effective strategy to accelerate the discovery of new fungal pigments and further exploration of their potential applications in different fields such as medicine and food industries.

Minos and Restless transposon insertion mutagenesis of psychrotrophic fungus for red pigment synthesis adaptive to normal temperature

The polar psychrotrophic fungus Geomyces sp. WNF-15A can produce high-quality natural red pigment for the potential use as edible pigment. However, it shows low-temperature-dependent synthesis of red pigment, which limits its large-scale industrial applications due to the difficult and high-cost bioprocess control. This study aims to develop transposon-mediated mutagenesis methods to generate mutants that are able to synthesize red pigment at normal temperature. Four transposable systems, including single and dual transposable systems, were established in this fungus based on the Minos from Drosophila hydei and the Restless from Tolypocladium inflatum. A total of 23 production-dominant mutants and 12 growth-dominant mutants were thus obtained by constructed transposable systems. At 14 °C and 20 °C, the MPS1 mutant strain achieved the highest level of red pigment (OD520 of 43.3 and 29.7, respectively), which was increased by 78.4% and 128.7% compared to the wild-type, respectively. Of note, 4 mutants (MPS1, MPS3, MPS4 and MPD1) successfully synthesized red pigment (OD520 of 5.0, 5.3, 4.7 and 4.9, respectively) at 25 °C, which broke the limit of the wild-type production under normal temperature. Generally, the dual transposable systems of Minos and Restless were more efficient than their single transposable systems for mutagenesis in this fungus. However, the positive mutation ratios were similar between the dual and single transposable systems for either Minos or Restless. This study provides alternative tools for genetic mutagenesis breeding of fungi from extreme environments.Graphical

Anthocyanin: a review of plant sources, extraction, stability, content determination and modifications

SummaryAnthocyanins are flavonoids of the polyphenol family, which are secondary metabolites of natural products synthesised by blueberries, mulberry and other plants. As a natural edible pigment, it is not only plentiful, non‐toxic and safe, but also has high nutritional value and pharmacological effects. Several studies have shown that anthocyanins have many health benefits such as improving vision, promoting antioxidant activity, capturing free radicals and treating cancer in humans. They are becoming increasingly popular in the fields of food and medicine. However, in terms of their structures, natural anthocyanins are unstable, easily deteriorating under the influence of their own structures and external factors, which greatly limits their application. Therefore, it is particularly important to use appropriate extraction methods and techniques to enhance the stability of anthocyanins. This article summarises the current research on anthocyanins in terms of plant sources, extraction, stability, content determination and structural modifications, and provides a reference for improving their application in the fields of food and medicine.

Comparative Transcriptomic and Metabolomic Analyses Reveal the Regulatory Effect and Mechanism of Tea Extracts on the Biosynthesis of Monascus Pigments.

Monascus pigments (MPs) are natural edible pigments with high safety and strong function, which have been widely used in food and health products. In this study, different types of tea extracts (rich in polyphenols) were used to regulate the biosynthesis of MPs. The results showed that 15% ethanol extract of pu-erh tea (T11) could significantly increase MPs production in liquid fermentation of Monaco’s purpureus M3. Comparative transcriptomic and metabolomic analyses combined with reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to further explore the regulatory mechanism of T11 on the biosynthesis of MPs. Comparative transcriptomic analysis showed that there were 1503 differentially expressed genes (DEGs) between the Con group and the T11 group, which were mainly distributed in carbohydrate metabolism, amino acid metabolism, energy metabolism, lipid metabolism, metabolism of terpenoids and polyketides, etc. A total of 115 differential metabolites (DMs) identified by metabolomics between the Con and T11 groups were mainly enriched in glutathione metabolism, starch and sucrose metabolism, alanine, aspartic acid and glutamate metabolism and glycine, serine and threonine metabolism, etc. The results of metabolomics were basically consistent with those of gene transcriptomics, indicating that the regulatory effect of T11 on the biosynthesis of MPs is mainly achieved through affecting the primary metabolic pathway, providing sufficient energy and more biosynthetic precursors for secondary metabolism. In this study, tea extracts with low economic value and easy access were used as promoters of MPs biosynthesis, which may be conducive to the application of MPs in large-scale industrial production. At the same time, a more systematic understanding of the molecular regulatory mechanism of Monascus metabolism was obtained through multi-omics analysis.

The synthesis of thermostable, strongly basic Anion-Exchange resins using Cross-Linked biguanide and its application in the extraction of Sodium copper chlorophyllin

Commercially available, strongly basic anion-exchange resins with quaternary ammonium groups have been widely used in the purification of natural plant extracts. However, under the condition of high temperature (greater than 60 °C), these resins could not be used for long periods because of the Hofmann degradation of the strongly basic groups. In this work, the synthesis of novel, thermally stable, strongly basic resins, which has a cross-link biguanide structure, was reported. The mechanism of thermal degradation was investigated, and the result indicated that not only the stability of the functional group but also the link mode between the functional group and the resin matrix should influence the thermal stability of the resin. In our experiment, the PDG2 resin was selected to separate sodium copper chlorophyllin (SCC), a type of edible pigment derived from plants, due to its optimal thermal stability and adsorption capacity. The adsorption mechanism and thermodynamics of PDG2 were also investigated. The results demonstrated that the main adsorption affinity of PDG2 toward SCC was due to the synergistic effects of the hydrophobic and ionic interactions, and the rise in temperature will benefit the adsorption equilibrium, which differed from the equilibrium for lutein. Therefore, under suitable gradient desorption conditions, a high-purity SCC extract was prepared. After eight cycles, the adsorption capacity of the PDG2 remained constant and reproducible at a high temperature (70 °C).

Neuroprotective Effects of an Edible Pigment Brilliant Blue FCF against Behavioral Abnormity in MCAO Rats.

Ischemic stroke leads to hypoxia-induced neuronal death and behavioral abnormity, and is a major cause of death in the modern society. However, the treatments of this disease are limited. Brilliant Blue FCF (BBF) is an edible pigment used in the food industry that with multiple aromatic rings and sulfonic acid groups in its structure. BBF and its derivatives were proved to cross the blood-brain barrier and have advantages on the therapy of neuropsychiatric diseases. In this study, BBF, but not its derivatives, significantly ameliorated chemical hypoxia-induced cell death in HT22 hippocampal neuronal cell line. Moreover, protective effects of BBF were attributed to the inhibition of the extracellular regulated protein kinase (ERK) and glycogen synthase kinase-3β (GSK3β) pathways as evidenced by Western blotting analysis and specific inhibitors. Furthermore, BBF significantly reduced neurological and behavioral abnormity, and decreased brain infarct volume and cerebral edema induced by middle cerebral artery occlusion/reperfusion (MCAO) in rats. MCAO-induced increase of p-ERK in ischemic penumbra was reduced by BBF in rats. These results suggested that BBF prevented chemical hypoxia-induced otoxicity and MCAO-induced behavioral abnormity via the inhibition of the ERK and GSK3β pathways, indicating the potential use of BBF for treating ischemic stroke

Mrada3 is required for sexual reproduction and secondary metabolite production in industrial fungi Monascus strain.

Monascus spp. are valuable industrial fungi for producing beneficial compounds. Because sporulation is often coupled with the production of secondary metabolites, the current study was performed to investigate how Mrada3 regulated asexual and sexual development and the production of edible pigments and mycotoxin. The functional characteristics of Mrada3 were identified by gene deletion and overexpression in Monascus ruber M7 (the wild-type, WT). The results revealed that the ΔMrada3 strain aborted sexual development, but it produced many more conidia than WT. RNA-seq data showed that the deletion of Mrada3 altered the expression levels of partial genes involved in sexual and asexual development. In addition, the deletion of Mrada3 also resulted in slower growth, lower pigment production and increased citrinin yield during the late period. For the Mrada3-overexpressed strain, the number of ascospores and pigment content were significantly higher than those of WT, but citrinin was slightly lower than that of WT. The Mrada3 gene plays a vital role in the sporulation development and secondary metabolism of Monascus species. Mrada3 is first identified as an essential regulator for sexual development in Monascus species, enriching the regulatory knowledge of sexual development in filamentous fungi.

Metabolomics Analysis Coupled with Weighted Gene Co-Expression Network Analysis Unravels the Associations of Tricarboxylic Acid Cycle-Intermediates with Edible Pigments Produced by Monascus purpureus (Hong Qu).

Monascus azaphilones pigments (MonAzPs) produced by microbial fermentation are widely used as food chemicals for coloring and supplying beneficial biological attributes. In this study, a fermentation perturbation strategy was implemented by separately adding different amino acids, and detecting the intracellular metabolome via UHPLC-Q-Orbitrap HRMS. With the aid of weighted gene co-expression network analysis, two metabolic intermediates, fumarate and malate, involved in the tricarboxylic acid cycle, were identified as the hub metabolites. Moreover, exogenous addition of fumarate or malate significantly promoted red pigment production, and reduced orange/yellow pigment production. The importance of the tricarboxylic acid cycle was further emphasized by detecting intracellular levels of ATP, NAD(P)H, and expression of oxidoreductase-coding genes located in the MonAzPs synthetic gene cluster, suggesting a considerable effect of the energy supply on MonAzPs synthesis. Collectively, metabolomics is a powerful approach to position the crucial metabolic regulatory factors, and facilitate the development of engineering strategies for targeted regulation, lower trial-and-error cost, and advance safe and controllable processes for fermented food chemistry industries.

Advances in the molecular regulation of anthocyanins in solanaceous vegetables

Anthocyanins are widely distributed water-soluble pigments that not only give the fruit colorful appearances, but also are important sources of natural edible pigments. In recent years, the interest on anthocyanins of solanaceous vegetables is increasing. This paper summarized the structure of anthocyanins and its biosynthetic pathway, the structural genes and regulatory genes involved in the biosynthesis of anthocyanins in solanaceous vegetables, as well as the environmental factors affecting the biosynthesis. This review may help clarify the synthesis and regulation mechanism of anthocyanins in solanaceous vegetables and make better use of anthocyanins for quality breeding of fruit colors.

A Review of Phycobiliproteins of Cyanobacteria: Structure, Function and Industrial Applications in Food and Pharmaceutical Industries

Phycobiliproteins are accessory photosynthetic pigments with a tetrapyrrole structure derived from bacterial strains that are organized on a thylakoid membrane inside a structure called phycobilisomes. Phycobiliproteins have been extensively commercialized in the manufacture of fluorescent probes for clinical and immunological analysis, in addition to their ability to dye with proven antioxidant and medicinal properties. Phycocyanin, Phycoerythrin and Allophycocyanin are the main types of phycobiliproteins that are widely used as useful food supplements today; however, in Iran, the true value of this natural pigment with bioactive properties has not been realized. Todays, the use of artificial colors and antioxidants in food product has led to an increase in cancer in many people. Therefore, awareness of the presence of natural food pigments of natural origin is of particular important. On the other hand, since so far no review article on extraction, separation and purification as well as evaluation of the biological activity of the pigment Phycoerythrin and Phycocyanin, has been published in Iran, so such review articles can pave the way for the introduction of natural edible pigments from cyanobacteria are considered to be usable in the food industry. Therefore, the purpose of this review article is to introduce the structure, function, biosynthesis and different methods of extraction of Phycobiliproteins in industrial dimensions along with different applications of Phycocyanin in food and pharmaceutical industries.

Structural identification and in vitro antioxidant activities of anthocyanins in black chokeberry (Aronia melanocarpa lliot)

Anthocyanins is a natural edible pigment with many health benefits. The aim of this work was the identification of anthocyanins present in Aronia melanocarpa using mass spectrometric features. The anthocyanins of the A. melanocarpa were analyzed by UVVis, HPLC‐DAD and LC‐EIS/MS methods. The four important anthocyanins were identified as follows: cyanidin‐3‐galactoside (68.68%), cyanidin‐3‐arabinoside (25.62%), cyanidin‐3‐glucoside (5.28%) and cyanidin‐3‐xyloside (0.42%). Among the four anthocyanin monomers, three anthocyanins with the highest content of A. melanocarpa were selected, and the antioxidant activity was studied with the total anthocyanins. The antioxidant capacity was cyanidin‐3‐galactoside > total anthocyanin > cyanidin‐3‐arabinoside > cyanidin‐3‐glucoside. The activity of the four anthocyanin samples was greater than ascorbic acid. The methodology described in this study will provide an effective tool for anthocyanins identification. Our results suggested that anthocyanins from A. melanocarpa exhibited effective antioxidant activity. These findings may be crucial in future research concerning chokeberry based functional food products.