Pigments cochineal

Pigment components have also been identified from their IR spectra. The infrared spectrum obtained from a purple pigment removed from MS 965 showed bands due to ultramarine blue and white lead. A red pigment (cochineal ) must also be present with the blue to produce the purple colour. 

To extract and evalnate the color pigments from cochineals Dactylopius coccus Costa), a simple method was developed. The procednre is based on the solvent extraction of insect samples nsing methanol and water (65 35, v/v) and a two-level factorial design to optimize the solvent extraction parameters temperature, time, methanol concentration in mixtnre, and yield. For hydrophilic colorants that are more sensitive to temperatnre, water is the solvent of choice. For example, de-aerated water extraction at low temperatnre was applied to separate yellow saffrole and carthamine from saffron (Carthamus tinctorius) florets that contain about 1% yellow saffrole and 0.3% red carthamine. ... 

Gonzalez, M. et al.. Optimizing conditions for the extraction of pigments in cochineals Dactylopius coccus Costa) using response surface methodology, J. Agric. Food Chem., 50, 6968, 2002. 

Cabrera, R. and Fernandez Lahore, H.M., Downstream processing of carminic acid from raw cochineal, in Proceedings of 4th International Congress on Pigments in Food, Hohenheim, Germany, Carle, R. et al., Eds., Shaker Verlag, Aachen, 2006, 203. 

Cochineal pigments are extracted from dried bodies of female insects with water or with ethanol the result is a red solution that is concentrated in order to obtain the 2 to 5% carminic acid concentration customary for commercial cochineal. For carmine lakes, the minimum content of carminic acid is 50%. An industrial procedure applied in Spain uses ammonium hydroxide as the extracting agent and phosphoric acid as the acidifying agent. For analytical purposes the extraction is carried out with 2 N HCl at 100°C. The chemical synthesis of carminic acid has also been reported and is the subject of European and United States patents. ... 

Carmine extracted from cochineal insects is one of the most used natural colorings for beverages and other foods. Some representative articles refer to isolation and spectrometric analysis or the use of HPLC or capillary electrophoresis (CE) to separate and characterize all cochineal pigments. Its active ingredient, carminic acid, was quantified by rapid HPLC-DAD or fluorescence spectrometry. Carminic acid, used as an additive in milk beverages, was separated within 9 min using a high-efficiency CE separation at pH 10.0 after a previous polyamide column solid phase extraction (SPE), ... 

Schweppe, H. and R. Runge (1986), Carmine Cochineal carmine and kermes, in Feller, R. E. (ed.), Artists Pigments, Cambridge Univ. Press, New York, pp. 225-283. 

Madder, Armenian cochineal, lac dye historical samples pigment and wall painting Alizarin, munjistin, purpurin, xanthopurpurin, rubiadin, laccaic acid A, laccaic acid B, carminic acid, kermesic acid, flavokermesic acid HCI/MeOH/ h2o A H20 B ACN with TFA 275 nm/ESI ( ) HPLC optimization... 

M. Gonzalez, M.G. Lobo, J. Mendez and A. Carnero, Detection of colour adulteration in cochineals by spectrophotometric determination of yellow and red pigment groups, Food Control, 16,105 112(2005). 

Natural colours include annatto, anthocyanins, beetroot red (betalaines), caramel, carotenoids, cochineal and lac pigments, flavanoids, chlorophylls and tumeric. There is a trend towards encapsulating natural colours for food use, but this is not yet reflected in the extraction techniques described in the published analytical methods. Lancaster and Lawrence (1996) described the extraction and... 

Fig. 2.32. Chromatograms obtained at 420 and 500 nm for pure cochineal (a) and for cochineal adulterated by erythrosin (b), at a concentration of 0.35 X10-3 kg per kg cochineal, and by trans-fi-carotene (c) at a concentration of 6X10-3 kg per kg cochineal. Cochineal pigments dcH, dcIH, dcIV and dcVII, unknown pigments of D. coccus Costa ca, carminic acid fl, flavokermesic acid and ka, kermesic acid. marks the peak of the added colourant. Reprinted with permission from M. Gonzalez et al. [72].

Fig. 3.6 Cathodic SWV curves for three quinone dyes and pigments lawson (1, a quasireversible process), alizarin lake (2, a reversible process) and cochineal red (3, a quasireversible process). Scans from open-circuit potential toward negative potentials. Insets the net, forward and backward current components are shown for alizarin lake and cochineal red (reprinted from [186] with permission)...

Figure 2.16 compares the SQWV responses obtained for silk fibbers pigmented with (a) granado (b) alazor (c) curcuma, (d) weld, and (e) cochineal red in contact with acetic/acetate buffer. This voltammetry yields clearly different responses for the involved dyes, thus allowing for an electrochemical identification of pigments in samples. 

Some potential interfering materials are other red pigments FD C Red No. 40, FD C Red No. 3, cochineal, and beet powder (betalain pigments). The presence of alternative colorants may be suspected if the /wis-max at pH 1.0 is high (550 nm, more typical of betalain pigments), or if a bright red coloration is found at pH 4.5 (potential presence of artificial dyes). 

Fourier transform infrared microspectroscopy applied to Byzantine manuscripts in the Special Collections Department of the University of Chicago Library revealed the use of numerous additives to the paint mixture including kaolin, hide glue, egg yolk, and other proteinaceous materials. Some evidence suggests that cochineal was used as a red pigment. 

The spectrum in Figure 7 is the result of the subtraction of the spectra ultramarine blue and white lead. Similar spectral features are present in Figure 8, a reference spectrum of crude cochineal (from Peruvian Coccus cacti). This reference spectrum was taken from the darker red, almost black, part of the dried insect. An important consideration is that if the region from 1400 to 1800 cm-1 is expanded, a pair of doublets become evident at 1465 and 1472 cm"1 and at 1708 and 1734 cm-1. These same bands appear in the reference spectrum at 1463 and 1472 cm"1 and at 1708 and 1734 cm"1. The fact that the frequencies of these doublets match suggests that the red pigment may very well be cochineal. 

Flesh-colored and red pigments removed from MS 232 (Greek gospel book) have spectral features similar to those in Figures 7 and 8. This similarity suggests that cochineal was also used as the red pigment in this manuscript. 

Carminic acid, a naturally occurring red pigment extracted from the cochineal insect, contains only carbon, hydrogen, and oxygen. It was commonly used as a dye in the first half of the nineteenth century. It is 53.66% C and 4.09% H by mass. A titration required 18.02 mL of 0.0406 M NaOH to neutralize 0.3602 g of carminic acid. Assuming that there is only one acidic hydrogen per molecule, what is the molecular formula of carminic acid ... 

Laccifer lacca Kerr), and is widely used for coloring food. It is known that the red color is derived from a water-soluble pigment including laccaic acids A, B, C, and E. Cochineal color extracted from the dried female bodies of the scale insect (Coccus cacti L.) is water-soluble and has a reddish color. The main coloring component is carmic acid. 

---