Colourings anthocyanins

Anthocyanins usually give a purple red colour. Anthocyanins are water soluble and amphoteric. There are four major pH dependent forms, the most important being the red flavylium cation and the blue quinodial base. At pHs up to 3.8 commercial anthocyanin colours are ruby red as the pH becomes less acid the colour shifts to blue. The colour also becomes less intense and the anthocyanin becomes less stable. The usual recommendation is that anthocyanins should only be used where the pH of the product is below 4.2. As these colours would be considered for use in fruit flavoured confectionery this is not too much of a problem. Anthocyanins are sufficiently heat resistant that they do not have a problem in confectionery. Colour loss and browning would only be a problem if the product was held at elevated temperatures for a long while. Sulfur dioxide can bleach anthocyanins - the monomeric anthocyanins the most susceptible. Anthocyanins that are polymeric or condensed with other flavonoids are more resistant. The reaction with sulfur dioxide is reversible. 

Beetroot red, betanin Elderberry colour Anthocyanins Amaranth Tartrazine... 

Garcia-Viguera, C. and Bridle, R, Influence of structure on colour stability of anthocyanins and flavylium salts with ascorbic acid, Food Chem., 64, 21, 1999. 

Hubbermann, E.M. et al., Influence of acids, salt, sugars and hydrocolloids on the colour stability of anthocyanin rich black currant and elderberry concentrates, Eur. Food Res. Technol, 223, 83, 2006. 

Stintzing, F.C., Trichterborn, J., and Carle, R., Characterisation of anthocyanin-beta-lain mixtures for food colouring by chromatic and HPLC-DAD-MS analyses. Food Chem., 94, 296, 2006. 

Reyes, L.R and Cisneros-ZevaUos, L., Degradation kinetics and colour of anthocyanins in aqueous extracts of purple- and red-flesh potatoes Solanum tuberosum L.), Food Chem., 100, 885, 2007. 

Fossen, T., Cabrita, L., and Andersen, 0.M., Colour and stability of pure anthocyanins influenced by pH including the alkaline region. Food Chem., 63, 435, 1998. 

Wilska-Jeszka, J. and Korzuchowska, A., Anthocyanins and chlorogenic acid copig-mentantion — Influence on the colour of strawberry and chokeberry juices, Z. Leb-ensm. Unters Forsch., 203, 38, 1996. 

Somers, T.C. and Evans, M.E., Wine quabty correlations with colour density and anthocyanin equilibria in a group of young red wines, J. Set Food Agric., 25, 1369, 1974. 

Keepers, J.W. and James, T.L., A theoretical smdy of distance determinations from NMR two-dimensional nuclear Overhauser effect spectra, J. Mag. Resort, 57, 404, 1984. Kemp, W., Organic Spectroscopy, 3rd ed., W.H. Ereeman, New York, 1991. Figueiredo, P. et al., New aspects of anthocyanin complexation intramolecular copigmentation as a means for colour loss Phytochemistry, 41, 301, 1996. 

Gonnet, J.R, Colour effects of co-pigmentation of anthocyanins revisited. 1. A colorimetric definition using the CIELAB scale. Food Chem., 63, 409, 1998. 

The optimized RPLC UV-Vis ESI MS method for all typical blue colourants (indi-goids, hematein, tannins, anthocyanins and selected flavonoids) was used for the identification of dyes extracted from a thread taken from an Italian tapestry of unknown origin from the collection of the National Museum in Warsaw (Poland). It was found that to obtain the red-blue colour of the fibre a mixture of dyestuffs was probably used. The presence of indigotin, tannic and ellagic acid (at m/z 301, NI), as well as carminic acid, suggested the use of indigo and cochineal. Reseda luteola could also have been used due to the presence of luteolin and apigenin. 

Disadvantages Dark coloured materials, due to the presence of anthocyanins, in particular are not suitable for the assay without strong dilution of the crude preparation... 

Bridle P and Timberlake CF. 1997. Anthocyanins as natural food colours-selected aspects. Food Chem... 

Patras A, Brunton NP, DaPieve S and Butler F. 2009. Impact of high pressure processing on total antioxidant activity, phenolic, ascorbic acid, anthocyanin content and colour of strawberry and blackberry puree. Innov Food Sci Emerg Technol doi 10.1016/j.ifset.2008.12.004. 

Anthocyanins. Anthocyanins are water soluble and are responsible for the colour of most red fruits and berries. Some 200 individual anthocyanins have been identified. It has been estimated that... 

Anthocyanins are extracted commercially using either acidified water or alcohol. The extract is then vacuum evaporated to produce a commercial colour concentrate. The raw materials can be blackcurrants, hibiscus, elderberry, red cabbage or black grape skins. The most commonly used commercially are black grape skins, which can be obtained as a by-product. 

Anthocyanins can form complexes with metal ions such as tin, iron and aluminium. The formation of a complex, as expected, alters the colour, usually from red to blue. Complex formation can be minimised by adding a chelating agent such as citrate ions. Another problem with anthocyanins is the formation of complexes with proteins. This can lead to precipitation in extreme cases. This problem is normally minimised by careful selection of the anthocyanin. 

Torreggiani, D., Fomi, E., Guercilena, I., Maestrelli, A., Bertolo, G., Archer, G.P., Kennedy, C.J., Bone, S., Blond, G., Contreras-Lopez, E., and Champion, D. 1999a. Modification of glass transition temperature through carbohydrates additions Effect upon colour and anthocyanin pigment stability in frozen strawberry juices. Food Res. Int. 32, 441 146. 

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). 

Hermann (2000) described a rapid automated method involving generation of a known amount of free radicals and the detection of the excess by photochemiluminescence. Test kits are available for determination of total water-soluble antioxidants, fat-soluble antioxidants and ascorbic acid. A luminometric method was developed for the determination of antioxidative activity and was subsequently applied to anthocyanin and betalaine colour concentrates (Kuchta et al., 1999). The method involved quantification of the interruption in luminescence from the hydrogen peroxide-horse radish peroxidase-luminol system in the presence of antioxidants. 

The spectra were recorded in the positive-ion mode in the range of m/z 120-1 500. Some chromatograms illustrating the effect of aldehydes on the interaction of mv3gl and B2-3 -gallate are shown in Fig. 2.120. The chromatograms demonstrate that different aldehydes influence differently the formation of anthocyanin-flavanol pigments. The results of HPLC-MS measurements are compiled in Table 2.94. Because free aldehydes display an unpleasant aroma in Port wine these reactions may improve the quality of wines and contribute to the colour formation [266],... 

A.M. Vivar-Quintana, C. Santos-Buelga and J.C. Rivas-Gonzalo, Anthocyanin-derived pigments and colour of red wines. Anal. Chim. Acta 458 (2002) 147-155. 

Anthocyanins, in association with other compounds, such as flavones, are responsible for the colour of certain flowers. An anthocyanin found in rose petals is cyanin it can be isolated as its chloride. The corresponding anthocyanidin, cyan id in, exists as the pentahydroxy salt in acidic media, but as the pH increases it gives first a quinone and then an anion. Each of these forms has a different colour (see Scheme 5.1). 

Figueiredo, P. et al., New aspects of anthocyanin complexation. Intramolecular copigmentation as a means for colour loss Phytochemistry, 41, 301, 1996. 

Gonnet, J.-F., Colour effects of co-pigmentation of anthocyanin revisited — 3. A further description using CIELAB differences and assessment of matched colours using the CMC model. Food Chem., 75, 473, 2001. 

Bakker, J. and Timberlake, C.F., Isolation, identification and characterization of new colour-stable anthocyanins occurring in some red wines, J. Agric. Food Chem., 45, 35, 1997. 

Kammerer, D. and Carle, R., Quantification of anthocyanins in black carrot extracts Daucus carota ssp. Sativus var. atrirubens Alef.) and evaluation of their colour properties, Eur. Food Res. Technol, 219, 479, 2004. 

Fernandez-Lopez et al.. Dependence between colour and individual anthocyanin content in ripening grapes, Food Res. Int., 31, 667, 1999. 

Mozetic, B. et al.. Changes of anthocyanins and hydroxycinnamic acids affecting the skin colour during maturation of sweet cherries Primus avium L.), Lebensm.-Wiss. u.-Technol, 37, 123, 2004. 

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