Food Pigments Research Articles

Contaminant-Activated Visible Light Photocatalysis

Pristine titanium dioxide (TiO2) absorbs ultraviolet light and reflects the entire visible spectrum. This optical response of TiO2 has found widespread application as white pigments in paper, paints, pharmaceuticals, foods and plastic industries; and as a UV absorber in cosmetics and photocatalysis. However, pristine TiO2 is considered to be inert under visible light for these applications. Here we show for the first time that a bacterial contaminant (Staphylococcus aureus—a MRSA surrogate) in contact with TiO2 activates its own photocatalytic degradation under visible light. The present study delineates the critical role of visible light absorption by contaminants and electronic interactions with anatase in photocatalytic degradation using two azo dyes (Mordant Orange and Procion Red) that are highly stable because of their aromaticity. An auxiliary light harvester, polyhydroxy fullerenes, was successfully used to accelerate photocatalytic degradation of contaminants. We designed a contaminant-activated, transparent, photocatalytic coating for common indoor surfaces and conducted a 12-month study that proved the efficacy of the coating in killing bacteria and holding bacterial concentrations generally below the benign threshold. Data collected in parallel with this study showed a substantial reduction in the incidence of infections.

Current perspective of yellowish-orange pigments from microorganisms- a review

Natural yellowish-orange pigments are derived from bacteria, yeasts, fungi and microalgae, including Chryseobacterium, Monascus and Chlorella. The purpose of this review is to provide an overview of these pigments in various aspects towards exploiting them for numerous functions. These pigments are produced in various shades of yellow-orange and categorised as carotenoids, anthraquinones, zeaxanthin, flexirubin and other compounds. They served as alternative colourants to replace hazardous and toxic synthetic pigments. Researchers are in progress to increase the pigment yield by improving the strains genetically, optimising the fermentation process and utilising cheap agro-industrial waste to reduce the production cost. Yellowish-orange pigments are applied in food, pharmaceuticals, cosmetics and textile industries. This review summarises the current technology status and challenges, economics, biosynthesis of pigment, novel strategies for production of yellowish-orange pigments, biological properties of pigments and metabolic engineering of microorganism with a focus on applications of pigments in food, pharmaceutical, dyeing industries as well as on other applications.

The eminence status of bacterial pigments under different aspects

Several bacteria such as Flavobacterium, Serratias, Chromobacterium and Streptomyces that produce different pigments are playing a significant role in various fields of sciences. Alternatively, current knowledge about bacterial pigments is limited to medical bacteriology, for instance their importance in virulence factors and protective features, however recently the investigators have revealed the supplementary consequence of pigments in food, textile and pharmaceutical aspects.

Extraction and characterization of anthocyanins from Nitraria tangutorun bobr. dry fruit and evaluation of their stability in aqueous solution and taurine-contained beverage

This study aimed to extract and identify anthocyanins from Nitraria tangutorun Bobr. dry fruit and evaluate the stability of anthocyanins in aqueous solution and taurine-contained beverage. Extraction at 68 °C for 30 min using 54% ethanol rendered an extract with 386.22 mg/100 g of anthocyanins. Fourteen anthocyanins in N. tangutorun dry fruit were identified using HPLC-DAD-ESI-MS/MS, and six of them were found in N. tangutorun dry fruit for the first time. The stability of anthocyanins and changes in color density and antioxidant activity of anthocyanin aqueous solution were evaluated at various pH and temperature levels using an accelerated thermal-stability assay. The degradation of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins and the loss of color density followed first-order model at studied conditions (R2 > 0.91); and the loss of antioxidant activity followed first-order model at 80 and 90 °C (R2 > 0.94). The Ea of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins were higher at pH 3 than that at pH 4 and 5 implying that the degradation of them at a lower pH level was more susceptible to temperature. Although the anthocyanins and color density were markedly loss with increasing the pH and temperature levels, the anthocyanin aqueous solution exhibited remarkable antioxidant capacity. In the beverage with or without taurine, the thermal degradation of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside and total anthocyanins also followed first-order model (R2 > 0.91), and 300 mg/100 mL of taurine provides protection for the stability of cyanidin-3-O-(trans-p-coumaroyl)-diglucoside (t1/2=438.61 min) and total anthocyanins (t1/2=391.53 min). N. tangutorun anthocyanins is promising natural food pigments.

Variation in the mating system of Bixa orellana L. (achiote) under three different agronomic systems

Bixa orellana L. (achiote), is a tropical species that produces high amounts of bixin, used as a commercial food pigment. In Yucatan, B. orellana (achiote) is cultivated under three different agronomic systems: backyard (solar), polyculture (milpa), and monoculture. Two promising phenotypes affecting bixin production have been identified. The phenotypes differ in flower and fruit colour, fruit dehiscence and bixin contents. Reflecting differences in plant density, species diversity and management factors among agronomic systems and differences in flowering synchrony between phenotypes, mating system parameters might vary, such as outcrossing rates (tm and ts), biparental inbreeding (tm-ts;rpm- rps), the fixation index of maternal plants (F) and paternity correlation (rpm). To compare such parameters between different B. orellana phenotypes among agronomic systems, 10 offspring from 20 genetic families of B. orellana per agronomic system were amplified using sequence-related amplified polymorphism (SRAP) molecular markers. MLTR software was used assuming a mixed mating system. Plants sown in backyard showed a mixed mating system, while in poly- and monoculture, they showed predominantly an outcrossing system; biparental inbreeding was similar in backyard, poly- and monoculture; the maternal inbreeding coefficient was higher in backyards than in poly- and monoculture; and plants in backyards and monoculture are less promiscuous than plants in polyculture. Variations between phenotypes within each agronomic system were also recorded. B. orellana displays a mixed mating system affected by the agronomic system. Thus, the selection of offspring should consider variation in the mating system in the design of alternative breeding improvement programs.

Nanoparticle-induced oxidation of corona proteins initiates an oxidative stress response in cells.

Titanium dioxide nanoparticles (TiO2 NPs), used as pigments and photocatalysts, are ubiquitous in our daily lives. Previous work has observed cellular oxidative stress in response to the UV-excitation of photocatalytic TiO2 NPs. In comparison, most human exposure to TiO2 NPs takes place in the dark, in the lung following inhalation or in the gut following consumption of TiO2 NP food pigment. Our spectroscopic characterization shows that both photocatalytic and food grade TiO2 NPs, in the dark, generate low levels of reactive oxygen species (ROS), specifically hydroxyl radicals and superoxides. These ROS oxidize serum proteins that form a corona of proteins on the NP surface. This protein layer is the interface between the NP and the cell. An oxidized protein corona triggers an oxidative stress response, detected with PCR and western blotting. Surface modification of TiO2 NPs to increase or decrease surface defects correlates with ROS generation and oxidative stress, suggesting that NP surface defects, likely oxygen vacancies, are the underlying cause of TiO2 NP-induced oxidative stress.

Natural food pigments application in food products

Natural pigments, food compounds, are responsible for the colour of the products. These additives can impart, to deepen or renew the colour of the product, if it has been lost while processing. They also improve the taste of the product and facilitate its identification. It is hard to imagine today’s food industry without the use of pigments. Presently, more and more conscious con­sumers are demanding products to be coloured with natural pigments or any pigment added to the final product. Artificial pigments are considered to be harmful and undesirable so food manufacturers focus on the use of natural colour substances. 16 natural pigments are presently permitted to be used. These compounds are: betalains – betanin, quinones – cochineal, flavonoids – anthocyan­ins, isoprenoids – carotene, annatto (bixin, norbixin), paprika extract, lutein, canthaxanthin, porphyrins – chlorophylls and chlorophyllins and copper complexes of these compounds, and others: caramels, curcumin, or plant coal.

Natural Pigments: Stabilization Methods of Anthocyanins for Food Applications.

The production of natural food pigments continues to grow worldwide. The global market is expected to grow at a compound annual growth rate of 6.22%, by revenue, over the period 2015 to 2019. Pigments such as anthocyanins, carotenoids, betalains, and chlorophylls have been used to color foods. However, there are challenges related to color losses during food processing, storage, and commercialization due to a low stability of natural pigments compared to synthetic colorants. This review summarizes the most recent studies and patents aimed at enhancing anthocyanin stability in food systems. The stabilizing methods include additions of copigment compounds, such as polymers, phenolic compounds, and metals. In addition, the exclusion of O2 during processing and storage, hard-panned candy coating methods for blue, green, and brown colors, and various encapsulation techniques were considered. Combining strategies and evaluating new materials capable of stabilizing anthocyanins will enhance their potential for use as value-added natural food pigments.

Studies on preparation of Bio-Paints using fungal bio-colors

Purpose – This paper aims to isolate fungal strains producing natural colours, explore their application as colourant in paints and develop cost-effective durable natural paints. Design/methodology/approach – Fungal strains producing natural colours of different shades were isolated. Colourant production was carried out by fermentation method. Natural lime, milk, oil-in-water emulsion paints using natural microbial colours and eco-friendly ingredients were prepared. Bio-paint applications were carried out and evaluated. Findings – Our results indicate that microbes in general and fungi in specific represent dependable source of variety of natural colours, and cost-effective durable natural paints can be prepared with commonly available natural ingredients using scientific information based on history of paints. Research limitations/implications – Natural colours are gaining importance because of their use in health, nutrition, pharmaceutical, textile and environmental applications. Nature is quite rich in several types of colourants. Chemical synthesis of synthetic dyes is complex and not environmental friendly. Microbial dyes manufactured can evade inherent environmental problems of synthetic dyes and offer significant opportunity as a colourant in paints. However, only generally regarded as safe microbial strains are to be considered for colour production. Practical implications – Choosing natural alternatives to protect the health and environment is the need of hour. Fungal colourants are relatively more stable and robust and offer significant opportunity as a colourant in paints. Cost-effective durable natural paints can be prepared using selected stable fungal colourants with commonly available natural ingredients. High diversity of rich and complex natural colourants can be obtained from microorganisms. With the available techniques of fermentation, natural colours can be produced in large quantities of on an economically viable scale and explored for their applications. Social implications – Bio-paints are eco-friendly natural paints, low volatile organic compounds (VOC) paints or organic paints alternate to conventional paints. Most of these natural paints are durable, breathable, prevent moisture problems, contribute to a positive room climate, use safer technology and are less energy-intensive than conventional latex paints to produce. These paints improve indoor air quality and reduce urban smog and offer beneficial characteristics such as low odour, excellent durability and a washable finish. Originality/value – Many of the old art works that still survive today are a tangible proof and evidence of beauty and durability of natural paints. Organic materials used in these paints include natural pigments of mineral, plant and animal origin and other raw biodegradable ingredients. Successful commercialisation of many microbial pigments for food and textile applications is reported in literature. Therefore, present research work aims at developing natural paints using microbial pigments and recipes that have been successfully used by people for years.

Can lutein replace annatto in the manufacture of Prato cheese?

Abstract Prato cheese is a Brazilian yellow-orange cheese traditionally colored with annatto. However, the aim of this study was to replace annatto with lutein, a natural yellow food pigment with potent antioxidant properties. Accordingly, we evaluated the maintenance of antioxidant activity of two concentrations of lutein (16 and 32 mg L−1) in Prato cheese throughout 60 days of ripening, as well as changes in color, pH, texture and ripening profiles, and sensory acceptance of lutein containing Prato cheese. We observed that lutein added to milk was transferred to the curd and antioxidant activity was maintained throughout ripening for both lutein concentrations. The cheese containing the higher concentration of lutein was slightly redder in color than the others; however, the main color changes were due to the ripening. In addition, Prato cheeses containing both lutein concentrations demonstrated similar sensory acceptance compared to cheese containing annatto. Ripening indexes (extension and depth), pH, and texture profile parameters were not affected (p ≥ 0.05) by addition of lutein. Therefore, Prato cheese was found to be a good matrix carrier for lutein, maintaining the antioxidant activity of the colorant. Furthermore, lutein can replace annatto without affecting the properties and acceptance of Prato cheese.

Prunus mahaleb L. fruit extracts: a novel source for natural food pigments

There is an increasing consumer and retailer demand for new natural colorants. Anthocyanins are a class of molecules already used as water-soluble natural colorant and for their health effects. Prunus mahaleb L. is a tree native to the Mediterranean area, producing highly pigmented small-stone fruits currently not used for fresh consumption due to their astringent and sour taste. In the present study, we set up a protocol to obtain a “mahaleb fruit concentrated extract” (mfce) and characterized it chemically by high-performance liquid chromatography/diode array detection. Anthocyanins, flavonols, flavanols, coumarin, sugars, ascorbic acid and organic acids were identified and quantified. After characterization, the antioxidant capacity of the mfce was assayed in vitro by three different methods: Trolox equivalent antioxidant capacity, Oxygen Radical Absorbance Capacity and Folin–Ciocalteu assays. The concentrated extract produced and characterized in this study showed a high content of anthocyanins, flavonols and coumarin and a strong antioxidant capacity. Therefore, mfce may be of interest as a natural food colorant and as an ingredient in the formulation of functional foods.

Rapid method for quantification of seven synthetic pigments in colored Chinese steamed buns using UFLC-MS/MS without SPE.

Synthetic pigments are still used instead of natural pigments in many foods and their residues in food could be an important risk to human health. A simple and rapid analytical method combining the low-cost extraction protocol with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of seven synthetic pigments used in colored Chinese steamed buns. For the first time, ethanol/ammonia solution/water (7:2:1, v/v/v) was used as extraction solution for the synthetic pigments in colored Chinese steamed buns. The results showed that the property of the extraction solution used in this method was more effective than critic acid solution, which is used in the polyamide adsorption method. The limits of quantification for the seven synthetic pigments ranged from 0.15 to 0.50 μg/kg. The present method was successfully applied to samples of colored Chinese steamed buns for food-safety risk monitoring in Zhejiang Province, China. The results found sunset yellow pigment in six out of 300 colored Chinese steamed buns (from 0.50 to 32.6 μg/kg).

Extraction and Purification of Pigment from Purple Sweet Potato Wine Vinasse

Purple sweet potato pigment is a natural food pigment with bright color and multiplies biological functions such as antioxidant activity etc. There is a large amount of unused pigment in the vinasse of purple sweet potato wine. Therefore, in this study, the extraction processes of purple sweet potato pigment from purple sweet potato wine vinasse, as well as its purification conditions were investigated. As the results, 0.9% citric acid-95% ethanol (2/3, v/v) was a suitable extraction solvent to obtain the higher yield of purple sweet potato pigment from vinasse. AB-8 column chromatography showed that the loading ratio of 1/10 (w/v) of resin and pigment with the solvent of 40% ethanol at the flow rate of 2 mL/min were the optimal conditions for the purification of purple sweet potato pigment.

COLORFUL LIFE HEALTHY LIFE

The information provided in this article is to obtain a further understanding of the beneficial health effects of various food pigments naturally occurring in plant products. The bright colors of many vegetables contribute much to their appeal. The colors result from the various pigments contained in their tissues. Most of the pigments occur in plastids –specialized bodies lying in the protoplasm of the cell. Sometimes the water – soluble pigments are dissolved in the vacuoles and not generally distributed throughout the cell. Thesepigments display various colors and are made up of different phytochemicals commonly found in the food matrix such as orange (β-carotene), yellowish-green (lutein), green (chlorophyll), and blue-purple (anthocyanin). Lycopene is the red colored pigment abundantly found in red colored fruits and vegetables such as tomato, papaya, pink grapefruit, pink guava and watermelon.

Effect of low-frequency magnetic field on formation of pigments of Monascus purpureus

Monascus purpureus is a key fungus used to produce food pigments from secondary metabolites. Low-frequency magnetic field (LF-MF) affects production of M. purpureus secondary metabolites as one of the cultivation environments. The objective of this study was to measure optimum strength of induced magnetic field and duration of exposure for yellow and red pigment production of M. purpureus in solid-state fermentation. There was a 65.4 and 59.2 % increase in peak yield of yellow and red pigments compared to the control when the treatments were exposed to a magnetic field induction at 0.4 mT on the 8–9th day of incubation time. From kinetics of yellow and red pigment production, yield of yellow and red pigments was significantly increased in the samples exposed to magnetic field from the 8th to 11th day compared with that of the control group. LF-MF could increase the production rates of yellow pigments from 221.25 to 381.75 and red pigments from 165.00 to 292.50 U/g day. It could also significantly prolong the quickly generate time of yellow pigment. The appropriate magnetic field treatment could increase the efficiency of yellow and red pigment production.

Effect of water content on the acid–base equilibrium of cyanidin-3-glucoside

Laser Flash Photolysis was employed to measure the deprotonation and reprotonation rate constants of cyanidin 3-monoglucoside (kuromanin) in water/methanol mixtures. It was found that the deprotonation rate constant kd decreases with decreasing water content, reflecting the lack of free water molecules around kuromanin, which may accommodate and stabilize the outgoing protons. On the other hand, the reprotonation rate constant, kp, increases with the decrease in water concentration from a value of kp=2×1010lmol−1s−1 in water up to kp=6×1010lmol−1s−1 at 5.6M water concentration in the mixture. The higher value of kp at lower water concentrations reflects the fact that the proton is not freely escaping the solvation shell of the molecule. The deprotonation rate constant decreases with decreasing water content, reflecting the lack of free water molecules around kuromanin that can accommodate the outgoing protons. Overall, the acidity constant of the flavylium cation decreases with the decrease in water concentration from pKa values of 3.8 in water to approximately 4.8 in water-depleted media, thus shifting the equilibrium towards the red-coloured form, AH+, at low water contents.The presence, or lack, of water, will affect the colour shade (red to blue) of kuromanin. This is relevant for its role as an intrinsic food component and as a food pigment additive (E163).

Microencapsulated beetroot juice as a potential source of betalain

Red beet is a rich source of betalain pigments, which can protect against age-related diseases. Betalain pigment can be used as a natural additive for food, cosmetics and drugs in the form of beet juice as well as beet powder. Processing stability in food is the most important issue nowadays. Microencapsulation of pigments creates stable powders. The aim of this study was to investigate the effect of carrier type on stability of beetroot pigments. Raw material used in the study was 100% beetroot juice. Low-crystallised maltodextrin, Arabic gum and a mixture of both (1:1) were used as carriers. Drying was carried out in a spray-drier at a disc speed of 39,000rpm and a solution flux rate of 0.3 and 0.8×10−6m3s−1. The inlet air temperature was 160°C. In powders physical properties such as hygroscopicity, dry matter solubility and size, which can influence future application, were tested. The highest violet pigment content was observed in powders based on Arabic gum, but the content of yellow pigment was low. Reverse results were seen for microparticles with maltodextrin. Moreover, for a longer period of time microcapsules of Arabic gum and beetroot pigments were stable, because of their lower hygroscopicity in comparison to maltodextrin. Nevertheless, the authors recommend beetroot pigments obtained with maltodextrin as natural food pigments for food supplements.

Simultaneous determination of red and yellow artificial food colourants and carotenoid pigments in food products

A method for simultaneously determining four artificial food colourants [Red Nos. 2 (R2) and 40 (R40), Yellow Nos. 5 (Y5) and 6 (Y6)] and three carotenoids [lycopene, lutein, and β-carotene] was developed. They were successfully separated by the developed high pressure liquid chromatography (HPLC) method combined with a photo diode array detector. The detection limit (at signal to noise>4) was from the lowest of 0.2ng/mL for lutein to the highest of 50.0ng/mL for R40. With a two-phase solvent and ultrasound-assisted extraction, the recoveries of the artificial and natural pigments in fifteen different types of food products were between 80.5–97.2% and 80.1–98.4%, respectively. This HPLC method with the ultrasound-assisted extraction protocol could be used as a sensitive and reliable analysis technique in simultaneously identifying and quantifying the reddish and yellowish pigments in different foods regardless of they are artificial food colourants or/and natural carotenoids.

Role of anthocyanin-enriched purple-fleshed sweet potato p40 in colorectal cancer prevention.

Anthocyanins, the natural pigments in plant foods, have been associated with cancer prevention. However, the content of anthocyanins in staple foods is typically low and the mechanisms by which they exert anticancer activity is not yet fully defined. We selected an anthocyanin-enriched purple-fleshed sweet potato clone, P40, and investigated its potential anticancer effect in both in vitro cell culture and in vivo animal model. In addition to a high level of total phenolics and antioxidant capacity, P40 possesses a high content of anthocyanins at 7.5 mg/g dry matter. Treatment of human colonic SW480 cancer cells with P40 anthocyanin extracts at 0-40 μM of peonidin-3-glucoside equivalent resulted in a dose-dependent decrease in cell number due to cytostatic arrest of cell cycle at G1 phase but not cytotoxicity. Furthermore, dietary P40 at 10-30% significantly suppressed azoxymethane-induced formation of aberrant crypt foci in the colons of CF-1 mice in conjunction with, at least in part, a lesser proliferative PCNA and a greater apoptotic caspase-3 expression in the colon mucosal epithelial cells. These observations, coupled with both in vitro and in vivo studies reported here, suggest anthocyanin-enriched sweet potato P40 may protect against colorectal cancer by inducing cell-cycle arrest, antiproliferative, and apoptotic mechanisms.

Separation of Natural Food Pigments in Saponified and Un-Saponified Paprika Oleoresin by Ultra High Performance Supercritical Fluid Chromatography (UHPSFC)

The natural pigments in paprika were rapidly and efficiently separated by ultra high performance supercritical fluid chromatography. The separation of both un-saponified and saponified mixtures of paprika oleoresin were optimized, with run times of 10.6 min. Three different C18 columns, a cyano, silica and diol column, all 3 × 100 mm, with 1.8 μm particles were compared. The best separation for the un-saponified sample was found with an SB-C18 column, while the saponified samples were best separated on a bare silica, RX-Sil column. A SB-CN column allowed near optimum separation of both the unsaponified, and saponified samples, with similar run times. The best mobile phase was carbon dioxide (CO2) modified with isopropyl alcohol (IPA), with a composition gradient. Fingerprints of several commercial pepper products indicated that one appeared to be colored with artificial dyes, while the color of a chili powder may have been enhanced with a paprika extract. Spectra, using CO2 with IPA as modifier, produced a single maximum at 453 nm, which appears to represent up to a 30 nm solvatochromic shift from the maxima in most organic solvents. Acetonitrile (ACN) as modifier produced spectra with two maxima and a similar solvatochromic shift. These results appear to be the first on saponified paprika oleoresin samples using SFC. It is also the first detailed report on the separation of un-saponified samples. The results are up to six times faster than comparable results by HPLC. It appears that SFC is a viable, superior alternative to HPLC for the analysis of this important commercial product, without using ACN, or chlorinated solvents.