Pigments caramel

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... 

Numerous CE separations have been published for synthetic colours, sweeteners and preservatives (Frazier et al., 2000a Sadecka and Polonsky, 2000 Frazier et al., 2000b). A rapid CZE separation with diode array detection for six common synthetic food dyes in beverages, jellies and symps was described by Perez-Urquiza and Beltran (2000). Kuo et al. (1998) separated eight colours within 10 minutes using a pH 9.5 borax-NaOH buffer containing 5 mM /3-cyclodextrin. This latter method was suitable for separation of synthetic food colours in ice-cream bars and fmit soda drinks with very limited sample preparation. However the procedure was not validated for quantitative analysis. A review of natural colours and pigments analysis was made by Watanabe and Terabe (2000). Da Costa et al. (2000) reviewed the analysis of anthocyanin colours by CE and HPLC but concluded that the latter technique is more robust and applicable to complex sample types. Caramel type IV in soft drinks was identified and quantified by CE (Royle et al., 1998). 

Juices extracts (liquorize), spirits (orange, lemon), syrups (black currant), tinctures (ginger), and aromatic waters Mineral pigments (iron oxides), natural colorants, anthocyanins, carotenoids, chlorophylls riboflavine, red beetroot extract, and caramel synthetic organic dyes azo compounds... 

The most elementary, nontechnical method of identifying a polysaccharide is to burn it, observe the yellow-to-brown color, and sniff the perfumelike aroma that should be reminiscent of the aroma of maple syrup, if the test is positive. If the caramelized residue is shaken with egg white and a visible reaction produces an insoluble, pigmented deposit (melanoidin), it is empirical proof that the sample was a polysaccharide. 

Caramel colors are brown pigments produced by reaction of a saccharide with a browning accelerator. They can be considered a natural material as caramels may be formed in food. Caramels are prepared as food colors by heating a solution of a sugar (commonly glucose or sucrose) with the accelerator. The caramels can be classified as one of four types [1] shown in Table 11.1.1. 

Enzymes known as polyphenol oxidases cause enzymatic browning. Other names of the enzyme include phenolases and tyrosinases. The enzymes catalyze the conversion of monophenols and diphenols to quinones. The quinones can undergo a series of non-enzymatic reactions to produce brown, gray and black colored pigments, collectively known as melanins (11). Maillard reactions, caramelizations and ascorbic acid oxidations can produce similar types of colored compounds (12). For some food processing... 

Hodge and Rist (44) have shown the role of the Amadori rearrangement in color formation following reaction between aldoses and amino acids. The reaction can eventually lead to the development of caramel-like flavors, melanoidin pigment,... 

Apart from the derivatives of p-carotene, other pigments are the anthocyanins, the chlorophylls, cochineal, the betalaines, turmeric, caramel and riboflavin. In this account the historical background in brief, the chemistry of these pigments, their extraction from natural sources and their synthesis will be discussed. The present permitted natural substances and nature-identical synthetic materials (also described by the Food and Drugs Administration, the FDA, as colorants exempt from certification ) is quite small in number. Reference is also made to colourants no longer listed but which have an historical organic chemical significance such as for example brazilin and its relative haematoxylin. 

FIGUREII. IS Contribution of caramelization of glucose and fructose on brown pigment formation at 65°C in a glucose + fructose + glutamine model system (G, glucose F, fructose Gin, glutamine). 

Caramel in appearance, flame retardant to UL94V-0, simulates PP/ABS Beige, pigmentable, high temperature resistance, simulates PP/ABS. Black, high temperature resistance, simulates PP/ABS. 

Natural and natural-identical synthetic pigments approved for colouring food are described in detail in Chapter 9 and caramel colours, one of the oldest and most widely-used food colourings, in Section 4.7.6. They are hsted in Table 11.12. 

Bismuth oxychloride BroRM pnt r Calcium carbonate CaiUhBxanihtn caramel Carotene (11) (ij) Cl Pigment NVhite 14 Cl Pigment Mclo] 2 Cl Pigment While 18 17787.56 1 77163 77400 77220 40850 75130 fnaiuni)... 

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