Disposable Electrochemical Sensor for Food Colorants Detection by Reduced Graphene Oxide and Methionine Film Modified Screen Printed Carbon Electrode.

A facile synthesis of reduced graphene oxide (rGO) and methionine film modified screen printed carbon electrode (rGO-methionine/SPCE) was proposed as a disposable sensor for determination of food colorants including amaranth, tartrazine, sunset yellow, and carminic acid. The fabrication process can be achieved in only 2 steps including drop-casting of rGO and electropolymerization of poly(L-methionine) film on SPCE. Surface morphology of modified electrode was studied by scanning electron microscopy (SEM). This work showed a successfully developed novel disposable sensor for detection of all 4 dyes as food colorants. The electrochemical behavior of all 4 food colorants were investigated on modified electrodes. The rGO-methionine/SPCE significantly enhanced catalytic activity of all 4 dyes. The pH value and accumulation time were optimized to obtain optimal condition of each colorant. Differential pulse voltammetry (DPV) was used for determination, and two linear detection ranges were observed for each dye. Linear detection ranges were found from 1 to 10 and 10 to 100 µM for amaranth, 1 to 10 and 10 to 85 µM for tartrazine, 1 to 10 and 10 to 50 µM for sunset yellow, and 1 to 20 and 20 to 60 µM for carminic acid. The limit of detection (LOD) was calculated at 57, 41, 48, and 36 nM for amaranth, tartrazine, sunset yellow, and carminic acid, respectively. In addition, the modified sensor also demonstrated high tolerance to interference substances, good repeatability, and high performance for real sample analysis.

Preparation and synthetic dye decolorization ability of magnetic cross-linked enzyme aggregates of laccase from Bacillus amyloliquefaciens.

Laccases are versatile oxidases that are capable of decolorizing various synthetic dyes. Recombinant Bacillus amyloliquefaciens laccase was immobilized as magnetic cross-linked enzyme aggregates (M-CLEAs) for application in dye decolorization. Several parameters influencing the activity recovery were evaluated during the synthesis of M-CLEAs. With ammonium sulfate as precipitant, maximum activity was recovered by cross-linking with 0.16% glutaraldehyde for 1 h. The prepared M-CLEAs exhibited improved activity under alkaline conditions. It remained 74% activity after incubation at 60 °C for 5 h. Enhanced tolerance towards NaCl was also observed for the M-CLEAs, with 68% activity remaining in the presence of 1 M NaCl. The immobilized laccase could rapidly decolorize more than 93% of reactive black 5 and indigo carmine in 1 h, while its catalytic efficiency towards reactive blue 19 was relatively low. After four cycles of consecutive reuse, the M-CLEAs could decolorize 92% of indigo carmine. The easy recovery and reusability of M-CLEAs facilitate the potential application of bacterial laccase in dye decolorization.

Designing and preparing supramolecular fluorescent probe based on carminic acid and γ-cyclodextrins and studying their application for detection of 2-aminobenzidazole.

Supramolecular fluorescent probe, which was designed and modeled from carminic acid (CA) and γ-cyclodextrins (γ-CDs), was initially qualified and stated comprehensively. Fluorescence intensity of CA could be dramatically enhanced ∼850 a.u. through formation of a supramolecular fluorescent probe CA@γ-CDs. The super-probe was verified by geometric conformation and molecular docking, and subsequently characterized by FT-IR, NMR, XRD and fluorescence lifetime. Furthermore, the CA@γ-CDs probe was proved on the detection of fungicide 2-aminobenzidazole (2-BZ). Finally, fluorescence performance of CA and the application of the probe for molecular recognition were both motivated by γ-CDs significantly, which could facilitate the fluorescence detection of CA more extensively and precisely.

Photostability of organic red food dyes.

The shift from artificial to natural ingredients is a rising trend in the food industry. However, natural coloring agents tend to be less stable than their synthetic counterparts when exposed to light, air, changes in pH, and heat. This study compares the photostability of three organic red dyes, Red 40 (allura red AC), betanin and carminic acid, in aqueous and soft drink solutions. The degradation, traced through absorbance spectroscopy, is well fit to first-order kinetics. Two distinct timescales are observed in aqueous solution but only a single, faster decay in the soft drink matrix. Betanin is the least stable dye in both solvent environments and Red 40 exhibits the greatest destabilization in the soft drink solution. Anoxia has different impacts dependent upon both the dye and solvent system. The analysis provides further insight into the degradation mechanisms for these different red dyes and the role of environment on their photostability.

Carminic Acid Stabilized with Aluminum-Magnesium Hydroxycarbonate as New Colorant Reducing Flammability of Polymer Composites.

In this study, hybrid pigments based on carminic acid (CA) were synthesized and applied in polymer materials. Modification of aluminum-magnesium hydroxycarbonate (LH) with CA transformed the soluble chromophore into an organic-inorganic hybrid colorant. Secondary ion mass spectroscopy (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and UV-Vis spectroscopy were used to study the structure, composition, and morphology of the insoluble LH/CA colorant. Successful modification of the LH was confirmed by the presence of interactions between the LH matrix and molecules of CA. XPS analysis corroborated the presence of CA complexes with Mg2+ ions in the LH host. The batochromic shift in UV-Vis spectra of the organic-inorganic hybrid colorant was attributed to metal-dye interactions in the organic-inorganic hybrid colorants. Strong metal-dye interactions may also be responsible for the improved solvent resistance and chromostability of the modified LH. In comparison to uncolored ethylene-norbornene copolymer (EN), a modified EN sample containing LH/CA pigment showed lower heat release rate (HRR) and reduced total heat release (THR), providing the material with enhanced flame retardancy.

Boron Content of Some Foods Consumed in Istanbul, Turkey.

The boron content was determined in 42 different foods consumed in Istanbul, Turkey. Eleven species of fruit, ten species of vegetable, eight species of food of animal origin, four species of grain, two species of nuts, two species of legume, and five other kinds of foods were included to this study. They were analyzed by two methods: Inductively coupled plasma mass spectrometry (ICP-MS) technique and carminic acid assay, and the results of two methods were also compared. Boron concentration in foods ranged between 0.06-37.2 mg/kg. Nuts had the highest boron content while foods of animal origin had the lowest. A strong correlation was found between the results of the carminic acid assay and the ICP-MS technique (p = 0.0001, Pearson correlation coefficient: r = 0.956). Bland Altman analysis also supported this correlation. ICP-MS is one of the most common, reliable, and powerful method for boron determination. The results of our study show that spectrophotometric carminic acid assay can provide similar results to ICP-MS, and the boron content in food materials can be also determined by spectrophotometric method.

The red insect dyes: carminic, kermesic and laccaic acids and their derivatives.

Three groups of insect dyes are described: three cochineal dyes, the kermes dye and the lac dye. The major color components are carminic acid, kermesic acid and laccaic acids, respectively. These dyes are red anthraquinone derivatives. The chemical structures are described. All of these dyes have extensive histories that are related briefly; however, only American cochineal is of commercial importance today. Two manufactured derivatives of cochineal, carmine and acid-stable carmine (4-aminocarminic acid) are described in some detail including the chemical identity, toxicity, stability, and staining and non-staining applications.

Combining dietary phenolic antioxidants with polyvinylpyrrolidone: transparent biopolymer films based on p-coumaric acid for controlled release.

Polyvinylpyrrolidone (PVP) has probably been one of the most utilized pharmaceutical polymers with applications ranging from a blood plasma substitute to nanoparticle drug delivery, since its synthesis in 1939. It is a highly biocompatible, non-toxic and transparent film forming polymer. Although high solubility of PVP in aqueous environment is advantageous, it still poses several problems for some applications in which sustained targeting and release are needed or hydrophobic drug inclusion and delivery systems are to be designed. In this study, we demonstrate that a common dietary phenolic antioxidant, p-coumaric acid (PCA), can be combined with PVP covering a wide range of molar ratios by solution blending in ethanol, forming new transparent biomaterial films with antiseptic and antioxidant properties. PCA not only acts as an effective natural plasticizer but also establishes H-bonds with PVP increasing its resistance to water dissolution. PCA could be released in a sustained manner up to a period of 3 days depending on the PVP/PCA molar ratio. Sustained drug delivery potential of the films was studied using methylene blue and carminic acid as model drugs, indicating that the release can be controlled. Antioxidant and remodeling properties of the films were evaluated in vitro by free radical cation scavenging assay and in vivo on a murine model, respectively. Furthermore, the material resorption of films was slower as PCA concentration increased, as observed from the in vivo full-thickness excision model. Finally, the antibacterial activity of the films against common pathogens such as Escherichia coli and Staphylococcus aureus and the effective reduction of inflammatory agents such as matrix metallopeptidases were demonstrated. All these properties suggest that these new transparent PVP/PCA films can find a plethora of applications in pharmaceutical sciences including skin and wound care.

Heterologous production of the widely used natural food colorant carminic acid in Aspergillus nidulans.

The natural red food colorants carmine (E120) and carminic acid are currently produced from scale insects. The access to raw material is limited and current production is sensitive to fluctuation in weather conditions. A cheaper and more stable supply is therefore desirable. Here we present the first proof-of-concept of heterologous microbial production of carminic acid in Aspergillus nidulans by developing a semi-natural biosynthetic pathway. Formation of the tricyclic core of carminic acid is achieved via a two-step process wherein a plant type III polyketide synthase (PKS) forms a non-reduced linear octaketide, which subsequently is folded into the desired flavokermesic acid anthrone (FKA) structure by a cyclase and a aromatase from a bacterial type II PKS system. The formed FKA is oxidized to flavokermesic acid and kermesic acid, catalyzed by endogenous A. nidulans monooxygenases, and further converted to dcII and carminic acid by the Dactylopius coccus C-glucosyltransferase DcUGT2. The establishment of a functional biosynthetic carminic acid pathway in A. nidulans serves as an important step towards industrial-scale production of carminic acid via liquid-state fermentation using a microbial cell factory.

Effect of microencapsulated Jabuticaba (Myrciaria cauliflora) extract on quality and storage stability of mortadella sausage.

The aim of the present study was to add microencapsulated Jabuticaba aqueous extract (MJE) to mortadella as a natural dye and to evaluate its possible antioxidant and antimicrobial activity during refrigeration. Anthocyanins in the extract were quantified and identified. Three treatments of mortadella were prepared: without dye (Control), with cochineal carmine (Carmine) and with the addition of 2% MJE. We determined the chemical composition of mortadella, along with pH, instrumental color, lipid oxidation, microbiological characteristics (Escherichia coli, Staphylococcus aureus, Salmonella, sulphite-reducing Clostridium, aerobic mesophiles, aerobic psychrotrophics and lactic acid bacteria) and sensory acceptance during storage at 4 °C for 56 days. MJE showed high content of anthocyanins, with prevalence of cyanidin-3-glucoside. MJE improved sensory acceptance of texture and flavor of mortadella (P < 0.05), but we observed a slight decrease in color and aroma attributes (P < 0.05). Lipid oxidation of mortadella was not influenced by MJE or cochineal carmine. MJE also displayed a minor effect on physicochemical and microbiological characteristics during storage. As MJE did not alter most of mortadella sausage's evaluated characteristics, it could be used as a natural dye in order to make better use of agro industry waste and to create a meat product enriched with natural antioxidants.

Modification of wool protein fiber with plasma and dendrimer: Effects on dyeing with cochineal.

In this study, plasma treatment and a poly(propylene imine) dendrimer were employed to improve the dyeability of wool fibers with cochineal natural dye. FESEM, EDX, AFM and FTIR techniques were employed to investigate the effects of these treatments on chemical and physical properties of wool fibers. The etching of the surface layer of wool fibers and increased roughness after plasma treatment was confirmed by FESEM and AFM images. EDX and FTIR analyses confirmed the creation of oxygen-containing groups and attachment of dendrimer molecules on wool fibers after plasma and dendrimer treatments respectively. The effects of different dyeing parameters on dye absorption and the applicability of different isotherm and kinetic models on the dyeing process were investigated. The results showed that the kinetics of absorption of cochineal on raw, plasma-treated and dendrimer-treated fibers was best fitted with the pseudo-second-order model and the isotherms of the dyeing processes followed the Freundlich model.

Acaricidal Activity and Synergistic Effect of Thyme Oil Constituents against Carmine Spider Mite (Tetranychus Cinnabarinus (Boisduval)).

Studies examining the use of essential oils as replacements for synthetic insecticides require an understanding of the contribution of each constituent present, interactions among these components, and how they relate to overall toxicity. In the present study, the chemical composition of commercial thyme oil was identified by gas chromatography-mass spectrometry. Thyme oil and blends of its major constituents were tested for their acaricidal activitities against carmine spider mites (Tetranychus cinnabarinus (Boisduval)) using a slide-dip bioassay. Natural thyme oil showed greater toxicity than any single constituent or blend of constituents. Thymol was the most abundant component (34.4%), and also possessed the strongest acaricidal activity compared with other single constituents. When tested individually, four constituents (linalool, terpinene, p-cymene and carvacrol) also had activity, while α-pinene, benzoic acid and ethyl gallate had almost no activity. The toxicity of blends of selected constituents indicated a synergistic effect among the putatively active and inactive constituents, with the presence of all constituents necessary to reach the highest toxicity. The results indicated that thyme oil and some of its major constituents have the potential to be developed into botanical acaricides.

Colorimetric Determination of Pb2+ in Perfect Aqueous Solution Using Carminic Acid as a Selective Chemosensor.

The commercially available natural organic dye, carminic acid (CA), an anthraquinone derivative bearing hydroxyl and carboxyl groups as recognition sites was found to be a colorimetric probe for Pb2+ in perfect aqueous solution under neutral conditions with specific selectivity and high sensitivity. Upon addition of Pb2+, the absorption maximum of CA showed a large red shift, and the resulted color change from red to purple could be easily identified even by the naked eye. The chemical stoichiometric ratio between CA and Pb2+ was determined to be 1:2 through Job plot, Pb2+ titration, and kinetic experiments. Moreover, other environmental relevant metal ions induced no or minimal spectral and color changes. The reversibility of Pb2+ to CA with EDTA even through several cycles was established for practical applications. The results indicated that CA can be a good candidate for simple, convenient and reversible colorimetric detection of Pb2+ in aqueous solution even though it was hard to be applied to determine Pb2+ on the water testing by US EPA.

Kinetic Study of the Equilibration between Carminic Acid and Its Two Isomers Isolated from Cochineal Dye.

Carminic acid (CA) is a major component of cochineal dye used in food additives, cosmetics, and pharmaceuticals. CA and its isomers, 2-C-α-glucofuranoside and 2-C-ß-glucofuranoside of kermesic acid (DCIV and DCVII, respectively), were isolated from cochineal dye and the equilibrium constants (K) between CA, DCIV and DCVII were investigated. DCIV was partially converted to CA and DCVII, and DCVII was converted to CA and DCIV, whereas CA was very stable and only very slightly converted to DCIV and DCVII. Most of the DCIV and DCVII was converted to CA under aqueous conditions. The kinetic rate constants (k) for the degradation of DCIV within the first day of incubation at 24°C was determined to be 0.901 d-1 and for the degradation of DCVII it was determined to be 1.102 d-1. The k value for the formation of CA from the remaining DCIV was calculated to be 0.146 d-1 and for the formation of CA from the produced DCVII it was found to be 0.148 d-1. The K values were calculated as 1.22×10-7, 2.61×10-3 and 2.36×10-3 mol/L for CA, DCIV and DCVII, respectively. These findings will be helpful for ensuring the safety and for aiding the quality assurance of cochineal dye products.

Identification of natural red and purple dyes on textiles by Fiber-optics Reflectance Spectroscopy.

Understanding dye chemistry and dye processes is an important issue for studies of cultural heritage collections and science conservation. Fiber Optics Reflectance Spectroscopy (FORS) is a powerful technique, which allows preliminary dye identification, causing no damage or mechanical stress on the artworks subjected to analysis. Some information related to specific light scattering and absorption can be obtained in the UV-visible and infrared range (300-1400nm) and it is possible to discriminate the kind of support fiber in the near infrared region (1000-2500nm). The main spectral features of natural dye fibers samples, such as reflection maxima, inflection points and reflection minima, can be used in the differentiation of various red natural dyes. In this work, a set of dyed references were manufactured following Mexican recipes with red dyes (cochineal and brazilwood) in order to determine the characteristic FORS spectral features of fresh and aged dyed fibers for their identification in historical pieces. Based on these results, twenty-nine indigenous textiles belonging to the National Commission for the Development of Indigenous People of Mexico were studied. Cochineal and brazilwood were successfully identified by FORS in several pieces, as well as the mixture of cochineal and indigo for purple color.

Comparison of goblet cell staining methods in jejunal mucosa of turkey poults.

This study compared the intestinal goblet cell density of turkey poults at 2 different ages using Alcian blue-periodic acid-Shiff (AB-PAS) and mucicarmine stains. Neutral mucins are stained with periodic acid-Shiff whereas acidic mucins are stained with Alcian blue. Mucicarmine and AB-PAS are specific to the mucins of epithelial origin. Mucicarmine has only been used for the assessment of goblet cells in human specimens, and it may have advantages for use in animals as a result of the methodological simplicity of staining as compared to AB-PAS. A mid-section of jejunum was taken from 80 turkey poults at 21 and 28 d, and fixed in 10% buffered formalin for 48 h. Each fixed tissue was dehydrated with ethanol, cleared with Sub-X, placed in paraffin wax, prepared on 2 slides, cleared and hydrated. The 2 slides were randomly assigned to 2 treatments which consisted of AB-PAS and mucicarmine stains in a completely randomized design. Goblet cell counts were taken from four villi per slide and the villus height was measured and averaged. There was no difference in the goblet cell density between the staining methods AB-PAS and mucicarmine at 21 or 28 d posthatch. These results show that both staining methods are viable for assessment of goblet cell density in turkey poults.

Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods.

In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).

Adsorption of azo dyes from aqueous solution by the hybrid MOFs/GO.

In this work, a hybrid of chromium(III) terephthalate metal organic framework (MIL-101) and graphene oxide (GO) was synthesized and its performance in the removal of azo dyes (Amaranth, Sunset Yellow, and Carmine) from water was evaluated. The adsorption for azo dyes on MIL-101/GO was compared with that of MIL-101, and it was found that the addition of GO enhanced the stability of MIL-101 in water and increased the adsorption capacity. The maximum adsorption capacities of MIL-101/GO were 111.01 mg g(-1) for Amaranth, 81.28 mg g(-1) for Sunset Yellow, and 77.61 mg g(-1) for Carmine. The adsorption isotherms and kinetics were investigated, showing that the adsorption fits the Freundlich isotherm and the pseudo-second-order kinetic model. The recyclability of MIL-101/GO was shown by the regeneration by acetone. The high adsorption capability and excellent reusability make MIL-101/GO a competent adsorbent for the removal dyes from aqueous solution.

Enhanced chemiluminescence of carminic acid-permanganate by CdS quantum dots and its application for sensitive quenchometric flow injection assays of cloxacillin.

A novel chemiluminescence (CL) system is introduced based on the oxidation of carminic acid by KMnO4 in acidic conditions. CdS quantum dots (QDs) were synthesized using a facile hydrothermal method which efficiently enhanced the intensity of the CL system. A possible mechanism for the proposed system is presented using the kinetic curves, CL spectra, photoluminescence (PL), and ultraviolet-visible (UV-Vis) analysis. The emission intensity of the KMnO4-carminic acid-CdS QDs system was quenched in the presence of a trace level of cloxacillin. Based on this quenching effect, a novel and sensitive flow injection CL method was developed for determining cloxacillin concentrations. At optimal experimental conditions, the decreased CL intensity had a good linear relation with the cloxacillin concentration in the range of 0.008 to 22.0 mg L(-1). The detection limit (3σ) was 5.8 µg L(-1). The precision of the method was calculated by analyzing samples containing 4.0 mg L(-1) of cloxacillin (n=11), and the relative standard deviations (RSD%) were 2.08%. The feasibility of the method is also demonstrated for determining cloxacillin concentrations in environmental water samples and a pharmaceutical formulation.

Determination of boron in produced water using the carminic acid assay.

Using the carminic acid assay, we determined the concentration of boron in oilfield waters. We investigated the effect of high concentrations of salts and dissolved metals on the assay performance. The influence of temperature, development time, reagent concentration, and water volume was studied. Ten produced and flowback water samples of different origins were measured, and the method was successfully validated against ICP-MS measurements. In water-stressed regions, produced water is a potential source of fresh water for irrigation, industrial applications, or consumption. Therefore, boron concentration must be determined and controlled to match the envisaged waste water reuse. Fast, precise, and onsite measurements are needed to minimize errors introduced by sample transportation to laboratories. We found that the optimum conditions for our application were a 5:1 mixing volume ratio (reagent to sample), a 1 g L(-1) carminic acid concentration in 99.99% sulfuric acid, and a 30 min reaction time at ambient temperature (20 °C to 23 °C). Absorption values were best measured at 610 nm and 630 nm and baseline corrected at 865 nm. Under these conditions, the sensitivity of the assay to boron was maximized while its cross-sensitivity to dissolved titanium, iron, barium and zirconium was minimized, alleviating the need for masking agents and extraction methods.