The Colors of Health: Chemistry, Bioactivity, and Market Demand for Colorful Foods and Natural Food Sources of Colorants

Selection of dysfunctional alleles of bHLH1 and MYB1 has produced white grain in the tribe Triticeae

Grain color is a key agronomic trait that greatly determines food quality. The molecular and evolutionary mechanisms that underlie grain-color regulation are also important questions in evolutionary biology and crop breeding. Here, we confirm that both bHLH and MYB genes have played a critical role in the evolution of grain color in Triticeae. Blue grain is the ancestral trait in Triticeae, whereas white grain caused by bHLH or MYB dysfunctions is the derived trait. HvbHLH1 and HvMYB1 have been the targets of selection in barley, and dysfunctions caused by deletion(s), insertion(s), and/or point mutation(s) in the vast majority of Triticeae species are accompanied by a change from blue grain to white grain. Wheat with white grains exhibits high seed vigor under stress. Artificial co-expression of ThbHLH1 and ThMYB1 in the wheat endosperm or aleurone layer can generate purple grains with health benefits and blue grains for use in a new hybrid breeding technology, respectively. Our study thus reveals that white grain may be a favorable derived trait retained through natural or artificial selection in Triticeae and that the ancient blue-grain trait could be regained and reused in molecular breeding of modern wheat.

Ultrasound-assisted extraction versus traditional Soxhlet apparatus for the obtention of polyphenols, carotenoids and tocopherols from Tagetes erecta L. flowers

BACKGROUND

Tagetes erecta L., commonly known as American marigold, serves as a food plant used for the extraction of carotenoids such as lutein, employed both as culinary ingredient in certain dishes and for its ornamental and medicinal applications. Two extraction techniques, Soxhlet and ultrasound-assisted extraction (UAE), were used on two cultivars (yellow and orange) of T. erecta. Polyphenols were quantified using HPLC-tandem mass spectrometry, whereas carotenoids and tocopherols were determined using HPLC-diode array detection. Biological activity for antioxidant and antiglycation properties was carried out.

RESULTS

The best extraction yield was obtained for UAE (7.51% and 6.83% for yellow and orange flowers), corresponding with the largest amounts of polyphenols quantified. The highest content of tocopherols was obtained in the yellow cultivar extracted by Soxhlet (6499.3 ± 21.2 and 4671.0 ± 92.9 mg kg-1 dry extract for α- and γ-tocopherol). The antioxidant potential resulted higher in the orange Soxhlet extract, whereas the yellow Soxhlet extract displayed the best antiglycation activity (median 50% inhibitory concentration of 25.3 ± 3.3 μg mL-1).

CONCLUSION

Both extraction techniques showed interesting results in terms of bioactivity and compounds obtention. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Structural Insights into 4,5-DOPA Extradiol Dioxygenase from Beta vulgaris: Unraveling the Key Step in Versatile Betalain Biosynthesis

Betalains, a group of pigments widely distributed in various plants, are extensively applied in the food, beverage, and medicinal industries. The biosynthesis of betalains involves the enzymatic action of 4,5-DOPA-dioxygenase, which catalyzes the key ring-opening reaction of DOPA to produce betalamic acid, a crucial intermediate in the pathway. The crystal structure of a 4,5-DOPA-dioxygenase from Beta vulgaris (BvDOD) was determined in this study. The structural analysis revealed that BvDOD exhibited a structural fold similar to that of other members of the extradiol dioxygenase family. Moreover, the Fe-ligand residues His15, His53, and His229 indicated the enzyme's reliance on nonheme iron for catalyzing the ring-opening reaction. Molecular docking and mutational analysis identified two conserved residues, His119 and His175, in the active site essential for the catalytic reaction. In addition, Thr17, Asp254, and Tyr260 contributed to properly positioning the substrate in the active site. This study has provided structural insights into substrate recognition and catalytic mechanisms of BvDOD, which can be applied to develop enzymes for improved betalain production.

Identification and characterization of anthocyanins' composition and regulatory genes involved in anthocyanins biosynthesis in water dropwort (Oenanthe javanica)

MAIN CONCLUSION

This study showed that anthocyanin was the main pigments related to purple stem and OjUFGT1 is involved in anthocyanin glycosylation in water dropwort. Water dropwort is a kind of aquatic vegetable with many medicinal values. In the study, the green-stem water dropwort 'FQ1H' and purple-stem water dropwort 'Sq013' were selected as plant materials. The anthocyanins composition was determined by UPLC-MS/MS and the transcript profile was analyzed based on RNA-seq in water dropwort. Nine anthocyanins were identified from water dropwort by UPLC-MS/MS. Petunidin and anthocyanin have higher content, which play a crucial role in the formation of purple stem. In total, 20,478 DEGs were identified in the purple stem, which might have a high correlation with anthocyanin accumulation. The expressions of 26 DEGs encoding anthocyanin biosynthesis structural genes were determined. Furthermore, co-expression analysis indicated that many R2R3-MYB and bHLH transcription factors were potentially involved in anthocyanin biosynthesis. In vitro enzyme activity assay showed that glycosyltransferase OjUFGT1 recognizes UDP-galactose as glycosyl donor and converts cyanidin to cyanidin-3-O-galactoside. In summary, these results may facilitate the development of our breeding and utilization for the high-anthocyanin water dropwort in the future.

Fungal derived dye as potential photosensitizer for antimicrobial photodynamic therapy

Photodynamic therapy (PDT) combines light with a photosensitizing agent to target and destroy abnormal cells or pathogens, offering a non-invasive and precise approach. Applying microbial dyes in PDT presents a great opportunity because these compounds may absorb specific wavelengths of light, generating reactive oxygen species (ROS) that induce oxidative stress, leading to cell or microbial death. This study evaluated the extract of Talaromyces amestolkiae containing azaphilone red dyes obtained from cultivation process as photosensitizer (PS) in antimicrobial photodynamic therapy (aPDT). Initially the crude extract was obtained in incubator shaker varying the culture media composition. Following, the crude extract containing the red dyes exhibited non-toxicity in dark conditions across all concentrations tested. PDT experiments with different amounts of the crude extract at a light dose of 80 J.cm-2 and upon irradiation at 460 nm was studied. A complete reduction of Escherichia coli and approximately 2 log10 reductions of Staphylococcus aureus, Cutibacterium acnes and Enterococcus faecalis was achieved using 25 % (v.v-1) of the crude extract while 50 % (v.v-1) of the crude extract led to a complete reduction of both E. coli and S. aureus, and around 5 log10 reductions of C. acnes and E. faecalis. Importantly, minimal photodegradation of the PS occurred during irradiation across all concentrations studied. These findings highlight the potential of T. amestolkiae-derived red dyes extract for use in aPDT, demonstrating non-toxicity in the absence of light, good aqueous solubility, high photostability, and strong microbial reduction capabilities under specific light conditions.

Uncovering the light absorption mechanism of the blue natural colorant allophycocyanin from Arthrospira platensis using molecular dynamics

Phycobiliproteins of the cyanobacterium Arthrospira platensis, known as Spirulina, are protein-chromophore complexes which are used by the organism to capture light energy. Allophycocyanin and C-phycocyanin are prominent in providing a natural source of blue food coloring. An unresolved issue remains the rapid loss of the native conformation of the pigment, leading to altered color with changing pH. This study investigates color changes on a quantum mechanics scale. A model was established to predict color shifts upon environmental changes, while proposing a mechanism to elucidate pH-dependent chromophore dynamics. On average, the model predicts a hypsochromic shift of 34 nm, in close alignment with the experimentally determined 36 nm. Results show several key non-covalent interactions governing the dynamics of the pyrrole rings of allophycocyanin, particularly influenced by solvents and pH. Particularly noteworthy are the hydrogen bonds with arginine (R 86) and aspartic acid (D 87), contributing to the distinctive optical absorption properties. These findings aid in pigment selection and the targeting of specific phycocyanin regions for stabilization, reducing the dependence on artificial food colors.

Physicochemical characterization, bioactive compounds, and antioxidant activity of the wild berry Ribes magellanicum

The Patagonian wild berry Ribes magellanicum has promising applications in food and nutrition due to its flavor and the presence of health-promoting bioactive compounds. Relevant chemical, physicochemical, and structural characteristics of the fruit for its utilization as food were investigated. The average moisture content was 79.3% while protein, lipids, sugars, and crude fiber amounted to 7.4, 5.8, 64.3, and 14.5 g/100 g dry fruit, respectively. Average values of fruit diameter, number of seeds, juice yield, soluble solids, and pH were determined as 5 mm, 17, 59.2%, 15.5 °Brix, and 4.3, respectively. Total phenolic compounds amounted to 2543 mg/100 g dry weight, anthocyanins to 561 mg C3G/100 g dry weight, and carotenoids to 43.3 mg/100 g oil. ORAC and DPPH values were 36.0 and 15.8 mmol TE/100 g dry weight, respectively. Linoleic acid predominated in a lipid profile that exhibited a good ω-6/ω-3 ratio (1.37). The structure of the berry consisted of a skin (exocarp) and a pulp (mesocarp) that contained many seeds representing 54% of the weight of the berry. These characteristics of R. magellanicum are similar to other wild Patagonian berries that have found applications as foods due to their convenience and the presence of abundant bioactive compounds.

BAHD acyltransferase from dragon fruit enables production of phyllocactin in engineered yeast

Microbial fermentation can provide a sustainable and cost-effective alternative to traditional plant extraction to produce natural food colours. Betalains are a class of yellow to red water-soluble pigments. Even though over 80 betalain variants are known, betanin is the only betalain available as a food colourant on the market. Many variants are acylated, which can enhance their stability and change the hue, but very few acyltransferases responsible for the acylation are known. Therefore, we mined the transcriptomes of Celosia argentea var. cristata and Hylocereus polyrhizus for BAHD acyltransferases, enzymes likely involved in betalain acylation. In vivo screening of the enzymes in betanin-producing Saccharomyces cerevisiae revealed that the acyltransferase HpBAHD3 from H. polyrhizus malonylates betanin, forming phyllocactin (6'-O-malonyl-betanin). This is the first identification of a BAHD acyltransferase involved in betalain biosynthesis. Expression of HpBAHD3 in a Yarrowia lipolytica strain engineered for high betanin production led to near-complete conversion of betanin to phyllocactin. In fed-batch fermentation, the strain produced 1.95 ± 0.024 g/l phyllocactin in 60 h. This study expands the range of natural food colourants produced through microbial fermentation and contributes to elucidating the biosynthesis pathway of acylated betalains.

Sayed A. The protective effects of dietary microalgae against hematological, biochemical, and histopathological alterations in pyrogallol-intoxicated Clarias gariepinus

Microalgae have well-established health benefits for farmed fish. Thus, this study aims to explore the potential protective effects of Spirulina platensis, Chlorella vulgaris, and Moringa oleifera against pyrogallol-induced hematological, hepatic, and renal biomarkers in African catfish (Clarias gariepinus), as well as the histopathological changes in the liver and kidney. Fish weighing 200 ± 25 g were divided into several groups: group 1 served as the control, group 2 was exposed to 10 mg/L of pyrogallol, and groups 3, 4, and 5 were exposed to the same concentration of pyrogallol, supplemented with S. platensis at 20 g/kg diet, C. vulgaris at 50 g/kg diet, and M. oleifera at 5 g/kg diet, respectively, for 15 days. Exposure to pyrogallol led to decreased packed cell volume (PCV) and lymphocyte count, but these effects were alleviated by microalgae interventions. C. vulgaris and M. oleifera equally restored PCV and increased lymphocyte counts. Supplementation with C. vulgaris and M. oleifera successfully normalized both neutrophil and eosinophil counts. Pyrogallol intoxication engenders an increase in glycemic status, but C. vulgaris and M. oleifera effectively mitigated this rise. Pyrogallol-exposed fish exhibited signs of renal dysfunction, with increased serum creatinine and total cholesterol levels. A significant decrease in both erythrocytic cellular and nuclear abnormalities was observed following supplementation with microalgae. C. vulgaris and M. oleifera showed promise in decreasing serum glucose and creatinine levels, and improving hematological parameters, while S. platensis exhibited limited efficacy in this regard. Exposure to pyrogallol led to a notable decrease in serum superoxide dismutase activity and total antioxidant capacity (TAC), accompanied by an increase in serum malondialdehyde (MDA) levels. Diets enriched with C. vulgaris and M. oleifera effectively restored these parameters to normal levels, whereas S. platensis did not induce significant changes. None of the microalgae improved TAC except for M. oleifera, which significantly enhanced it. MDA levels returned to control levels equally and significantly across all groups. Interleukin-6 levels did not exhibit significant differences between any of the groups. Collectively, the histopathological changes induced by pyrogallol were most prominently alleviated in the pyrogallol + C. vulgaris and pyrogallol + M. oleifera groups, and to a limited degree in the pyrogallol + S. platensis group. While the tested microalgae did not cause hepatic or renal dysfunction, they did lead to metabolic abnormalities. The incorporation of microalgae into the diet holds significant importance in mitigating the metabolic and histological toxicity of pyrogallol and should be considered in the formulation of fish feed.

Native Mexican black bean purified anthocyanins fractionated by high-performance counter-current chromatography modulate inflammatory pathways

In addition to their pigment properties, the potential health benefits of anthocyanins have made them a subject of interest in recent years. This study aimed to obtain purified anthocyanin fractions from native Mexican black bean cultivars using Amberlite XAD-7 resin column and HPCCC and evaluate their anti-inflammatory properties using RAW 264.7 cells. The major anthocyanins in the purified anthocyanin fractions were delphinidin 3-glucoside (61.8%), petunidin 3-glucoside (25.2%), and malvidin 3-glucoside (12.2%). Purified anthocyanin fractions at 12.5 μg/mL effectively prevented LPS-induced ERK1/ERK2 phosphorylation and reduced the protein expression of COX-2 and mRNA expression of iNOS. Results showed that purified anthocyanin fractions have the potential to modulate the inflammatory response by inhibiting the production of pro-inflammatory mediators through the ERK1/ERK2 and NF-κB pathways. This study suggests that anthocyanins from black beans could be used as a natural strategy to help modulate inflammation-associated diseases.

Safety of tartrazine in the food industry and potential protective factors

Tartrazine belongs to the colors raising significant concerns regarding consumer safety at low doses relevant for real-life human exposure. Scientific literature continues to grow after the European Food Safety Authority (EFSA) re-evaluation in 2009 and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2016. Therefore, this review aims to collect recent knowledge on the toxicity issues of tartrazine, namely its genotoxicity, cytotoxicity, carcinogenicity, reproductive, developmental, and neurotoxicity, alterations of blood biochemical parameters, and hematotoxicity. The second part of the review covers the potential protective factors against the toxic effects of tartrazine based on the hypothesis of mitigation of oxidative stress induced by the color. The reviewed protective factors are crocin, royal jelly, fish oil, honey, acetylsalicylic acid, black caraway, blackthorn, turmeric, vitamin E, and riboflavin. This review concludes that tartrazine seems safe under the current acceptable daily intake (ADI) and the evidence on the potential protective factors is insufficient to reach any conclusion regarding their use.

Food Additives and Evolved Methods of Detection: A Review

Food additives are essential constituents of food products in the modern world. The necessity of food processing went up rapidly as to meet requirements including, imparting desirable properties like preservation, enhancement and regulation of color and taste. The methods of identification and analysis of such substances are crucial. With the advancement of technology, a variety of techniques are emerging for this purpose which have many advantages over the existing conventional ways. This review is on different kinds of additives used in the food industry and few prominent methods for their determination ranging from conventional chromatographic techniques to the recently evolved nano-sensor techniques.

Azaphilone pigments from the marine-derived Penicillium sclerotium UJNMF 0503 and their neuroprotective potential against H2O2-induced cell apoptosis through modulating PI3K/Akt pathway

Azaphilones represent a particular group of fascinating pigments from fungal source, with easier industrialization and lower cost than the traditional plant-derived pigments, and they also display a wide range of pharmacological activities. Herein, 28 azaphilone analogs, including 12 new ones, were obtained from the fermentation culture of a marine fungus Penicillium sclerotium UJNMF 0503. Their structures were elucidated by MS, NMR and ECD analyses, together with NMR and ECD calculations and biogenetic considerations. Among them, compounds 1 and 2 feature an unusual natural benzo[d][1,3]dioxepine ring embedded with an orthoformate unit, while 3 and 4 represent the first azaphilone examples incorporating a novel rearranged 5/6 bicyclic core and a tetrahydropyran ring on the side chain, respectively. Our bioassays revealed that half of the isolates exhibited neuroprotective potential against H2O2-induced injury on RSC96 cells, while compound 13 displayed the best rescuing capacity toward the cell viability by blocking cellular apoptosis, which was likely achieved by upregulating the PI3K/Akt signaling pathway.

Evaluation of Verbascum flower extracts as a natural source of pigments with potential health benefits

Crocins are bioactive glucosylated apocarotenoids that confer a yellow pigmentation. In addition to their coloring ability, crocins offer potential health benefits because of their antioxidant and anti-inflammatory properties. These compounds are present in the flowers and fruits of a few plant species, including saffron, gardenia, Buddleja and Verbascum species. Saffron extracts have been used for the formulation of functional foods. However, there is no evidence of the use of the other plants producing crocins in the food industry. This study evaluated the effect of the addition of ground dry flowers of two Verbascum species, with antioxidant activity, as well as dry fruit powder, from a recently engineered tomato plant producing fruits that accumulate high levels of crocins, as functional ingredients during the processing of rice, wheat cous-cous and maize noodles, providing a yellow pigmentation. Correlation analyses revealed that the increased antioxidant activity in the three food matrices was due to the presence of crocins, which showed no toxicity. Furthermore, in vitro digestion showed that crocins were more bioaccessible from rice than from cous-cous or maize noodles, inferring the importance of the food matrix in bio accessibility. The obtained results showed the commercial potential of Verbascum's flowers, as a source of crocins, natural pigments with antioxidant activities.

Berries as Foods: Processing, Products, and Health Implications

Berries are highly regarded as flavorful and healthy fruits that may prevent or delay some chronic diseases attributed to oxidative stress and inflammation. Berries are low in calories and harbor diverse bioactive phytochemicals, antioxidants, dietary fibers, and vitamins. This review delves into the main characteristics of fresh berries and berry products as foods and the technologies associated with their production. The main effects of processing operations and related variables on bioactive components and antioxidants are described. This review critically discusses why some health claims based on in vitro antioxidant data and clinical studies and intervention trials are difficult to assess. The review suggests that the beneficial health effects of berries are derived from a multifactorial combination of complex mixtures of abundant phenolic components, antioxidants, and their metabolites acting synergistically or additively with other nutrients like fibers and vitamins and possibly by modulating the gut microbiota.

Co-assembled whey protein and proanthocyanidins as a promising biocarrier for hydrophobic pterostilbene: Fabrication, characterization, and cellular antioxidant potential

The usage of food-derived polyphenols with different polarities has been limited by their instability and incompatibility. Therefore, a biocarrier was developed by co-assembly of whey protein isolate (WPI) and hydrophilic proanthocyanidin (PC) for loading hydrophobic pterostilbene (PTE). Such biocarrier has superior affinity for PTE than WPI alone, as determined by encapsulation efficiency and loading capacity assay, fluorescence quenching analysis, and molecular docking, whereas the assembly process was characterized by particle size and zeta potential, 3-dimensional fluorescence, and scanning electron microscopy. Circular dichroism and Fourier transform infrared spectroscopy spectra confirmed the α-helix to β-sheet and random coil transition of proteins during the formation of nanocomplexes. Whey protein isolate acted as a mediator through altering the binding mode of PC and PTE, allowing them to perform significant synergistic effects in enhancing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging and reducing H2O2-induced cell damage. This research may serve to develop new protein/polyphenol co-loading systems and offer a reliable nutritional fortification.

Gardenia yellow pigment: Extraction methods, biological activities, current trends, and future prospects

Food coloring plays a vital role in influencing consumers' food choices, imparting vibrant and appealing colors to various food and beverage products. Synthetic food colorants have been the most commonly used coloring agents in the food industry. However, concerns about potential health issues related to synthetic colorants, coupled with increasing consumer demands for food safety and health, have led food manufacturers to explore natural alternatives. Natural pigments not only offer a wide range of colors to food products but also exhibit beneficial bioactive properties. Gardenia yellow pigment is a water-soluble natural pigment with various biological activities, widely present in gardenia fruits. Therefore, this paper aims to delve into Gardenia Yellow Pigment, highlighting its significance as a food colorant. Firstly, a thorough understanding and exploration of various methods for obtaining gardenia yellow pigment. Subsequently, the potential functionality of gardenia yellow pigment was elaborated, especially its excellent antioxidant and neuroprotective properties. Finally, the widespread application trend of gardenia yellow pigment in the food industry was explored, as well as the challenges faced by the future development of gardenia yellow pigment in the field of food and health. Some feasible solutions were proposed, providing valuable references and insights for researchers, food industry professionals, and policy makers.

Green Solvents for Extraction of Natural Food Colorants from Plants: Selectivity and Stability Issues

Consumers associate the color of food with its freshness and quality. More and more attention is being paid to natural colorants that bring additional health benefits to humans. Such natural substances are the carotenoids (yellow to orange), the anthocyanins (red to blue), and the betalains (red and yellow), which are very sensitive to exposure to light, air, high temperatures, and chemicals. Stability and diversity in terms of color can be optimized by using environmentally friendly and selective extraction processes that provide a balance between efficacy, safety, and stability of the resulting extracts. Green solvents like water, supercritical fluids, natural deep eutectic solvents, and ionic liquids are the most proper green solvents when combined with different extraction techniques like maceration, supercritical extraction, and ultrasound-assisted or microwave-assisted extraction. The choice of the right extracting agent is crucial for the selectivity of the extraction method and the stability of the prepared colorant. The present work reviews the green solvents used for the extraction of natural food colorants from plants and focuses on the issues related to the selectivity and stability of the products extracted.

The structure of anthocyanins and the copigmentation by common micromolecular copigments: A review

Under natural physiological conditions, anthocyanins can keep bright and stable color for a long time due to the relatively stable acid-base environment of plant vacuoles and the copigmentation from various copigment substances, such as polyphenols, nucleotides, metallic ions and other substances. Therefore, the copigmentation caused by copigments is considered an effective way to stabilize anthocyanins against adverse environmental conditions. This is attributed to the covalent and noncovalent interactions between colored forms of anthocyanins (flavylium ions and quinoidal bases) and colorless or pale yellow organic molecules (copigments). These interactions are usually manifested in both hyperchromic effect and bathochromic shifts. In addition to making anthocyanins more stable, the copigmentation also could make an important contribution to the diversification of their tone. Based on the molecular structure of anthocyanins, this review focuses on the interaction mode of auxochrome groups or copigments with anthocyanins and their effects on the chemical and color stability of anthocyanins.

Obtaining and characterizing polyphenol extracts based on anthocyanins from Melinis minutiflora inflorescences and Plinia cauliflora fruits and application in gelatins

Anthocyanins are a class of compounds potentially used as food dyes. Thus, this study aimed to obtain and characterize natural extracts from Melinis minutiflora inflorescence (M), Plinia. cauliflora peel (JP) and P. cauliflora peel and seeds (JPS) and apply them as natural food dyes in gelatins. The extracts did not show statistically significant differences in pH values and water activity. The M and JPS extracts showed similar values of anthocyanins and total phenolic compounds and were higher than those from the JP extract. The M and JPS extracts showed a bathochromic effect, which was not observed for the JP extract. The bathochromic effect may indicate a possible complexation of anthocyanins. The color composition analysis revealed that the JP extract has a higher absorbance at a wavelength of 520 nm, indirectly suggesting the presence of more monomeric anthocyanins in its composition. The extract application test in gelatin did not change the texture properties of the gelatins. In addition, our findings revealed that the JPS extract had the best color stability after ten days of analysis, indicating that anthocyanin complexation with the phenolic compounds of P. cauliflora seeds contributed more effectively to anthocyanin stability in the model used.

Betacyanins obtained from alternative novel sources as natural food colorant additives: incorporated in savory and sweet food products

The aim of this study was to assess the performance and stability of betacyanin compounds present in enriched extracts of red-fleshed pitaya peels (Hylocereus costaricensis) and the flowers of Amaranthus caudatus; they were evaluated as natural food colorants in tagliatelle pasta and meringue cookies. The recovered natural extracts showed promising stability, maintaining a deep pink color over a storage time of 14 days, without deeply changing the chemical composition. A number of factors were assessed, including the microbial load, texture, color, nutritional value, and contents of organic acids, fatty acids, and even free sugars of the products. Some significant interactions between the type of colorant and storage time contributed to the changes in some analyzed parameters, as can be observed from the results for organic and fatty acids in the tagliatelle pasta and meringue cookies. Another significant achievement was the reduction in the microbial load during the storage time, which strengthens the antibacterial power of these natural extracts.

A Review of the Chemistry and Biological Activities of Natural Colorants, Dyes, and Pigments: Challenges, and Opportunities for Food, Cosmetics, and Pharmaceutical Application

Natural pigments are important sources for the screening of bioactive lead compounds. This article reviewed the chemistry and therapeutic potentials of over 570 colored molecules from plants, fungi, bacteria, insects, algae, and marine sources. Moreover, related biological activities, advanced extraction, and identification approaches were reviewed. A variety of biological activities, including cytotoxicity against cancer cells, antioxidant, anti-inflammatory, wound healing, anti-microbial, antiviral, and anti-protozoal activities, have been reported for different pigments. Considering their structural backbone, they were classified as naphthoquinones, carotenoids, flavonoids, xanthones, anthocyanins, benzotropolones, alkaloids, terpenoids, isoprenoids, and non-isoprenoids. Alkaloid pigments were mostly isolated from bacteria and marine sources, while flavonoids were mostly found in plants and mushrooms. Colored quinones and xanthones were mostly extracted from plants and fungi, while colored polyketides and terpenoids are often found in marine sources and fungi. Carotenoids are mostly distributed among bacteria, followed by fungi and plants. The pigments isolated from insects have different structures, but among them, carotenoids and quinone/xanthone are the most important. Considering good manufacturing practices, the current permitted natural colorants are: Carotenoids (canthaxanthin, β-carotene, β-apo-8'-carotenal, annatto, astaxanthin) and their sources, lycopene, anthocyanins, betanin, chlorophyllins, spirulina extract, carmine and cochineal extract, henna, riboflavin, pyrogallol, logwood extract, guaiazulene, turmeric, and soy leghemoglobin.

Complex plant protein prepared from rice protein and pea protein: Improve the thermal stability of betanin

Betanin (BN) is a kind of edible natural red pigment with a variety of biological activities, but the thermal instability of BN has critically restricted its application in food industry. In this study, complex plant protein (RP-PP) was constructed by rice protein (RP) and pea protein (PP) to study the thermal protection effect and protective mechanism on BN. Thermal degradation results indicated RP-PP significantly improved thermal protection effect, and the degradation rate of BN was decreased from 93.74 % to 56.48 % after heating at 80 ℃ for 60 min. The main interaction between RP-PP and BN was hydrophobic force based on the result of fluorescence spectroscopy, FTIR and molecular docking. In addition, a porous network structure of RP-PP was observed by SEM, and the pore structure gradually decreased at the presence of BN, which speculated BN was trapped in it. TEM observation showed that RP-PP gradually aggregated with the increasing BN concentration, leading to a significant increase in particle size and the formation of network structure. The BN acted as a bridge to the surrounding proteins in the aggregated complex and was encapsulated within it. The interaction and encapsulation may be the key reasons for the improved thermal stability of BN.

Towards chemical characterization and possible applications of juçara fruit: an approach to remove Euterpe edulis Martius from the extinction list

Juçara (Euterpe edulis Martius) is a palm widely distributed in the Atlantic Forest. It produces a non-climacteric, black-violet small fruit similar to the Amazonian açaí (Euterpe precatoria). The fruit is known as superfruit because it presents chemical characteristics of great importance, such as anthocyanins content. Regarding bioactive compounds and antioxidant scavenging capacity, it presents high anthocyanin (634.26 to 2,929 mg of cyanidin-3-glucoside 100 g-1) and total phenolic compounds (415.1 to 9,778.20 mg equivalents of gallic acid 100 g-1) contents. The soluble solid content ranges from 3.0 to 4.9% and its pH is higher than other tropical fruits (4.8 to 5.6). Despite the rich bioactive compound content of juçara fruits, this plant has been traditionally used for palm heart production. The accelerated and illegal palm heart exploitation, without the use of an adequate management has led to the risk of extinction of this species. In order to prevent this species from vanishing, several studies have valued the health characteristics of juçara fruit chemical composition. An economical approach has been the production of juçara pulp described as a source of bioactive compounds, which has attracted the attention of industrial field aiming the production of functional foods, foodstuff, cosmetics and pharmaceutical products. A full botanical and chemical characterization of juçara tree and fruit is presented in this paper, as well as suggestions to increase the use of this tropical fruit and derivatives.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05342-8.

Improved pH stability, heat stability, and functionality of phycocyanin after PEGylation

Phycocyanin (PC), a spirulina-derived protein-chromophore complex, suffers from poor techno-functional properties and is highly susceptible to aggregation and color changes upon heating and pH fluctuations. We tackled these issues by modifying PC via PEGylation. Electrophoresis and Fourier transform infrared spectroscopy proved successful conjugation of methoxy PEG (mPEG) chains on PC after PEGylation. Circular dichroism indicated highly ordered folding states adopted by PEGylated PC, which we attributed to the mPEG chains on the protein surface that sterically stabilized the protein structure. Consequently, the mPEG-PC conjugates exhibited high blue color intensity and improved thermodynamic stability. Further, benefit from an electrostatic shielding effect of mPEG chains, surface charges of PEGylated PC were neutralized over pH 2-9 and the blue hue of PC was stabilized against pH variations. Additionally, the flexible and hydrophilic mPEG polymers on the PC surface promoted protein-protein and protein-water interactions. PEGylated PC thus gained increased protein solubility, techno-functionality (emulsifying, foaming, and gelling performance), and antioxidant activities, when compared to unmodified PC. Heat-induced gels formed by mPEG-PC conjugates exhibited increased stiffness, higher water retention, and weak gel-type rheological properties. After PEGylation, the improved functional properties, bioactivity, and color stability against heat and pH fluctuations will facilitate food and pharmaceutical applications of PC.

Phycocyanin from Spirulina platensis bio-mimics quantum dots photocatalytic activity: A novel approach for dye degradation

In our present study, the photocatalytic degradation of malachite green (MG) an organic dye was carried out using a phycocyanin extract of Spirulina platensis under the irradiation of sunlight. The aim of the present study is to incorporate a simple, novel, an eco-friendly, and cost-effective degradation of dyes without using any harmful metals and chemicals. It was observed that 25 ppm of MG dye got degraded nearly to 100 % at 3 h. The UV absorbance studies indicate the absence of a peak at 620 nm which is a conclusive evidence for MG dye degradation. An optimization study of MG dye degradation was evaluated by Response Surface Methodology using Minitab module 20.4.0.0 statistical software and its percentage of degradation was statistically analyzed using analystat. The FT-IR studies of raw spectra show minimal variation; however, the deconvoluted spectra in the region of 1600-1700 cm^-1 indicate the variation in the secondary structure of amide I bands that leads to the dye degradation. The dye degradation study mainly follows the first-order kinetics between the time intervals of 60-180 min. The characteristics of degraded water were assessed by a TOC analyzer. The value of total inorganic carbon (TIC) in MG before treatment was 90 mg/L and seems to be slightly high when compared to MG after treatment which was found to be 87.65 mg/L and the adsorbent-treated water with a low value of 54.25 mg/L. These results well matched with the characteristics of normal water. The presence of phycocyanin in the degraded water was effectively removed by treating with activated carbon and it was confirmed with fluorescence analysis. These results support that the MG dye degradation was exhibited by phycocyanin extract and bio-mimics the quantum dot photocatalytic activity.

Evaluation of Antioxidant Capacity and Gut Microbiota Modulatory Effects of Different Kinds of Berries

Berries are fairly favored by consumers. Phenolic compounds are the major phytochemicals in berries, among which anthocyanins are one of the most studied. Phenolic compounds are reported to have prebiotic-like effects. In the present study, we identified the anthocyanin profiles, evaluated and compared the antioxidant capacities and gut microbiota modulatory effects of nine common berries, namely blackberry, black goji berry, blueberry, mulberry, red Chinese bayberry, raspberry, red goji berry, strawberry and white Chinese bayberry. Anthocyanin profiles were identified by UPLC-Triple-TOF/MS. In vitro antioxidant capacity was evaluated by four chemical assays (DPPH, ABTS, FRAP and ORAC). In vivo antioxidant capacity and gut microbiota modulatory effects evaluation was carried out by treating healthy mice with different berry extracts for two weeks. The results show that most berries could improve internal antioxidant status, reflected by elevated serum or colonic T-AOC, GSH, T-SOD, CAT, and GSH-PX levels, as well as decreased MDA content. All berries significantly altered the gut microbiota composition. The modulatory effects of the berries were much the same, namely by the enrichment of beneficial SCFAs-producing bacteria and the inhibition of potentially harmful bacteria. Our study shed light on the gut microbiota modulatory effect of different berries and may offer consumers useful consumption guidance.

Studies on the biosynthetic pathways of melanin in Auricularia auricula

Melanin is a natural pigment ubiquitously present in living organisms, including bacteria, fungi, plants, and animals. Melanin produced by the edible mushroom Auricularia auricula has a remarkable potential for resource development. Several A. auricula strains planted across China were collected and analyzed for mycelial growth rate and colony RGB value for color block. Further, the effects of various nutrients on melanin formation, including different carbon and nitrogen sources were evaluated to optimize medium for submerged fermentation. The pathways involved in the biosynthesis of melanin in A. auricula were investigated using an enzyme inhibitor assay and intermediate determination. In addition, the functional activity of purified A. auricula melanin was assessed. The highest melanin yield (1.797 g/L) was displayed by strain AU-3 in medium I. A. auricula melanin was composed of eumelanin, pheomelanin and 1,8-dihydroxynaphthalene melanin, and the biosynthetic pathways involved were Raper-Mason and 1,8-dihydroxynaphthalene melanin pathway. In addition, melanin purified from A. auricula exhibited substantial antioxidant, antibacterial, and antitumor activities. This article is protected by copyright. All rights reserved.

Pressurized aqueous solutions of deep eutectic solvent (DES): A green emergent extraction of anthocyanins from a Brazilian berry processing by-product

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PLE using DES aqueous solutions is an eco-friendly method for anthocyanin recovery.

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Pressurized DES solutions can be used to valorize the jaboticaba by-product.

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DES (ChCl:Pro and ChCl:Ma) solutions had yields 50% higher than conventional solvents.

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Recovered extracts showed antioxidant, anti-diabetic, and anti-obesity potential.

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Pressurized ChCl:Ma solution maintained the color and bioactivity of the extracts.

Deep eutectic solvents (DES) are emergent solvents with high extractability of bioactive compounds. Therefore, anthocyanin rich-fractions were recovered from jaboticaba peels by combining aqueous solutions of DES and pressurized liquid extraction (PLE). The extraction occurred at 10 MPa, 12 min, with conditions optimized through response surface methodology: 47% DES concentration, 90 °C, and 5.3 mL/min flow rate. PLE with different DES (choline chloride combined with propylene glycol or malic acid) solutions were compared to conventional solvents (water and acidified water) concerning yield, thermostability, antioxidant, anti-diabetic, and anti-obesity activities. DES solutions presented anthocyanin yields up to 50% higher than conventional solvents. ChCl:Ma, with the highest anthocyanin stability (Ea = 77.5 kJ.mol⁻¹), was a promising solvent concerning color, anti-diabetic and anti-obesity potential. Environmental analysis by Green Certificate and EcoScale indicated PLE with DES solutions is a green and efficient approach to recover anthocyanin from jaboticaba peel, providing useful extracts.

Natural Food Colorants and Preservatives: A Review, a Demand, and a Challenge

The looming urgency of feeding the growing world population along with the increasing consumers' awareness and expectations have driven the evolution of food production systems and the processes and products applied in the food industry. Although substantial progress has been made on food additives, the controversy in which some of them are still shrouded has encouraged research on safer and healthier next generations. These additives can come from natural sources and confer numerous benefits for health, beyond serving the purpose of coloring or preserving, among others. As limiting factors, these additives are often related to stability, sustainability, and cost-effectiveness issues, which justify the need for innovative solutions. In this context, and with the advances witnessed in computers and computational methodologies for in silico experimental aid, the development of new safer and more efficient natural additives with dual functionality (colorant and preservative), for instance by the copigmentation phenomena, may be achieved more efficiently, circumventing the current difficulties.

Modeling and Optimizing the Effect of Light Color, Sodium Chloride and Glucose Concentration on Biomass Production and the Quality of Arthrospira platensis Using Response Surface Methodology (RSM)

Arthrospira platensis (Spirulina) biomass is a valuable source of sustainable proteins, and the basis for new food and feed products. State-of-the-art production of Spirulina biomass in open pond systems only allows limited control of essential process parameters, such as light color, salinity control, or mixotrophic growth, due to the high risk of contaminations. Closed photobioreactors offer a highly controllable system to optimize all process parameters affecting Spirulina biomass production (quantity) and biomass composition (quality). However, a comprehensive analysis of the impact of light color, salinity effects, and mixotrophic growth modes of Spirulina biomass production has not been performed yet. In this study, Response Surface Methodology (RSM) was employed to develop statistical models, and define optimal mixotrophic process conditions yielding maximum quantitative biomass productivity and high-quality biomass composition related to cellular protein and phycocyanin content. The individual and interaction effects of 0, 5, 15, and 30 g/L of sodium chloride (S), and 0, 1.5, 2, and 2.5 g/L of glucose (G) in three costume-made LED panels (L) where the dominant color was white (W), red (R), and yellow (Y) were investigated in a full factorial design. Spirulina was cultivated in 200 mL cell culture flasks in different treatments, and data were collected at the end of the log growth phase. The lack-of-fit test showed that the cubic model was the most suitable to predict the biomass concentration and protein content, and the two-factor interaction (2FI) was preferred to predict the cellular phycocyanin content (p > 0.05). The reduced models were produced by excluding insignificant terms (p > 0.05). The experimental validation of the RSM optimization showed that the highest biomass concentration (1.09, 1.08, and 0.85 g/L), with improved phycocyanin content of 82.27, 59.47, 107 mg/g, and protein content of 46.18, 39.76, 53.16%, was obtained under the process parameter configuration WL4.28S2.5G, RL10.63S1.33G, and YL1.00S0.88G, respectively.

Biosynthesis and regulation of anthocyanin pathway genes

Anthocyanins are the phenolic compounds responsible for coloring pigments in fruits and vegetables. Anthocyanins offer a wide range of health benefits to human health. Their scope has expanded dramatically in the past decade, making anthocyanin control, influx, and outflow regulation fascinating for many researchers. The main culprit is anthocyanin stability and concentration form, which demands novel ways because these are critical in the food industry. This review aims to examine anthocyanin synthesis via triggering transcription genes that code for anthocyanin-producing enzymes. The balance between production and breakdown determines anthocyanin accumulation. Thus, increasing the anthocyanin content in food requires the stability of molecules in the vacuolar lumen, the pigment fading process, and a better understanding of the mechanism. The promising option is biosynthesis by metabolically engineered microorganisms with a lot of success. This study aims to look into and evaluate the existing literature on anthocyanin production, namely the biosynthesis of anthocyanin pathway genes, production by microbial cell factories, and the regulatory factors that can modulate the production of anthocyanins. Understanding these mechanisms will provide new biotechnological approaches.Key points• Factors affecting the regulation of anthocyanins• Focus on degradation, biosynthesis pathway genes, and alternative systems for the production of anthocyanins• Microbial cell factories can be used to produce large amounts of anthocyanins.

Bioactives and extracts affect the physico-chemical properties of concentrated whey protein isolate dispersions

Non-covalent complexation interactions are known to occur between bioactive compounds and proteins. While formulating with these components can have positive outcomes such as stabilization of colors and actives, it can also result in changes to the structures and physical properties of proteins, affecting product functionality and sensory attributes. Previous experiments reported measurable changes in the physico-chemical properties of whey protein isolate (WPI) dispersions upon formulation with Aronia berry extract, ascribing changes to protein-polyphenol (PP) interactions in the systems. Pure gallotannin, beet extract, and cranberry extract, providing a diverse variety structures and sizes, were selected for further experimentation and comparison with the effects of Aronia extract. Concentrated dispersions with varying WPI:sucrose ratios, formulated with several bioactives contents from multiple different sources were analyzed to identify the effects of different bioactives on physico-chemical properties of dispersions. Dispersions formulated with cranberry extract demonstrated the largest increases in surface tensions, viscosities, and particle sizes, while those formulated with beet extract were the least affected by the presence of bioactives, suggesting that different bioactives and extracts had varying propensities for complexation interactions with WPI, despite their relatively low levels of addition (0, 0.5, and 1%).

Graphical Abstract

Betalain plant sources, biosynthesis, extraction, stability enhancement methods, bioactivity, and applications

Betalains are plant pigments with functional properties used mainly as food dyes. However, they have been shown to be unstable to different environmental factors. This paper provides a review of (1) Betalain plant sources within several plant families such as Amaranthaceae, Basellaceae, Cactaceae, Portulacaceae, and Nyctaginaceae, (2) The biosynthesis pathway of betalains for both betacyanins and betaxanthins, (3) Betalain extraction process, including non-conventional technologies like microwave-assisted, ultrasound-assisted, and pulsed electrical field extraction, (4) Factors affecting their stability, mainly temperature, water activity, light incidence, as well as oxygen concentration, metals, and the presence of antioxidants, as well as activation energy as a mean to assess stability, and novel food-processing technologies able to prevent betalain degradation, (5) Methods to increase shelf life, mainly encapsulation by spray drying, freeze-drying, double emulsions, ionic gelation, nanoliposomes, hydrogels, co-crystallization, and unexplored methods such as complex coacervation and electrospraying, (6) Biological properties of betalains such as their antioxidant, hepatoprotective, antitumoral, and anti-inflammatory activities, among others, and (7) Applications in foods and other products such as cosmetics, textiles and solar cells, among others. Additionally, study perspectives for further research are provided for each section.

Impact of three phenolic copigments on the stability and color evolution of five basic anthocyanins in model wine systems

Phenolic copigments have important influence on red wine color. In this study, UV-visible spectrophotometer and UHPLC-Q-TOF-MS were combined to investigate the effects of three types of phenolic copigments (gallic acid, (-)-epicatechin, and quercetin-3-O-glucoside) on the stability and color properties of five common 3-O-monoglucosidic anthocyanins in model wine solutions. Results showed low concentrations (0.5 mM) of gallic acid and (-)-epicatechin protected anthocyanins from degradation, whereas high concentrations (8 mM) of them had the opposite effect. Quercetin-3-O-glucoside always improved the stability of anthocyanins despite its additive amount (0.1 mM or 0.4 mM). Even small quantity of (-)-epicatechin led to obvious yellow hue into the solution, and xanthylium derivatives generated from (-)-epicatechin were detected. Antagonistic effect among the three copigments was observed, probably as a result of competition of intermolecular copigmentation. Additionally, the stability of anthocyanins was significantly influenced by their structures: cyanidin-3-O-glucoside, peonidin-3-O-glucoside, and malvidin-3-O-glucoside were more stable than delphinidin-3-O-glucoside and petunidin-3-O-glucoside.

The interactions between anthocyanin and whey protein: A review

Anthocyanins (ACN) are natural pigments that produce bright red, blue, and purple colors in plants and can be used to color food products. However, ACN sensitivity to different factors limits their applications in the food industry. Whey protein (WP), a functional nutritional additive, has been shown to interact with ACN and improve the color, stability, antioxidant capacity, bioavailability, and other functional properties of the ACN-WP complex. The WP's secondary structure is expected to unfold due to heat treatment, which may increase its binding affinity with ACN. Different ACN structures will also have different binding affinity with WP and their interaction mechanism may also be different. Circular dichroism (CD) spectroscopy and Fourier transform infrared (FTIR) spectroscopy show that the WP secondary structure changes after binding with ACN. Fluorescence spectroscopy shows that the WP maximum fluorescence emission wavelength shifts, and the fluorescence intensity decreases after interaction with ACN. Moreover, thermodynamic analysis suggests that the ACN-WP binding forces are mainly hydrophobic interactions, although there is also evidence of electrostatic interactions and hydrogen bonding between ACN and WP. In this review, we summarize the information available on ACN-WP interactions under different conditions and discuss the impact of different ACN chemical structures and of WP conformation changes on the affinity between ACN and WP. This summary helps improve our understanding of WP protection of ACN against color degradation, thus providing new tools to improve ACN color stability and expanding the applications of ACN and WP in the food and pharmacy industries.

Study on the Potential Application of Impatiens balsamina L. Flowers Extract as a Natural Colouring Ingredient in a Pastry Product

Flowers of the genus Impatiens are classified as edible; however, their inclusion in the human diet is not yet a common practice. Its attractive colours have stirred great interest by the food industry. In this sense, rose (BP) and orange (BO) I. balsamina flowers were nutritionally studied, followed by an in-depth chemical study profile. The non-anthocyanin and anthocyanin profiles of extracts of both flower varieties were also determined by high-performance liquid chromatography coupled to a diode array and mass spectrometry detector (HPLC-DAD-ESI/MS). The results demonstrated that both varieties presented significant amounts of phenolic compounds, having identified nine non-anthocyanin compounds and 14 anthocyanin compounds. BP extract stood out in its bioactive properties (antioxidant and antimicrobial potential) and was selected for incorporation in "bombocas" filling. Its performance as a colouring ingredient was compared with the control formulations (white filling) and with E163 (anthocyanins) colorant. The incorporation of the natural ingredient did not cause changes in the chemical and nutritional composition of the product; and although the colour conferred was lighter than presented by the formulation with E163 (suggesting a more natural aspect), the higher antioxidant activity could meet the expectations of the current high-demand consumer.

Microbial pigments as an alternative to synthetic dyes and food additives: a brief review of recent studies

Synthetic coloring agents have been broadly utilized in several industries such as food, pharmaceuticals, cosmetic and textile. Recent surveys on the potential of teratogenicity and carcinogenicity of synthetic dyes have expressed concerns regarding their use in foods. Worldwide, food industries have need for safe, natural and new colorings to add variety to foods and make them appealing to consumers. Natural colorings not only expand the marketability of the food product, but also add further healthful features such as antibacterial, antioxidant, anticancer and antiviral properties. Novel microbial strains should be explored to meet the increasing global search of natural pigments and suitable techniques must be developed for the marketable production of new pigments, using microbial cultures, viz., fungi, and bacteria. To address the issue of the natural coloring agents, this review presents the recent trends in several studies of microbial pigments, their biological properties and industrial applications.