Food colourings

J. Walford, ed.. Developments in Food Colours, Vols. 1 and 2. Elsevier AppHed Science, London, 1980 and 1984. Includes chapters on synthetic and natral food colors used in the United States, and on the influence of color on the perception and choice of food. 

One of the few phytochemicals that has been subjected to the rigorous testing procedures required by food safety authorities is P-carotene, a naturally-occurring carotenoid that is also a pre-cursor of vitamin A in humans. It is increasingly used as a food colour since the food product can be claimed to contain all natural ingredients. For this reason, detailed toxicological studies were undertaken that enabled the Joint FAO/WHO Expert Committee for Food Additives (JECFA) to set an ADI of 0-5 mg/kg/bw/day based on a NOAEL of 50 mg/day and the application of an uncertainty factor of 10 (JECFA, 1974). This low factor was used because it was argued that the compound occurred naturally in food, that its use as a food additive would not lead to a substantial increase in the total amount normally consumed, and that there had been no reports of adverse effects in humans. The ADI would correspond to an acceptable intake in humans of up to 350 mg/day. 

The carotenoids are the most widespread group of pigments in nature, with an estimated yield of 100 million tonnes per annum. They are present in all photosynthetic organisms and responsible for most of the yellow to red colours of fruits and flowers. The characteristic colours of many birds, insects and marine invertebrates are also due to the presence of carotenoids, which have originated in the diet. Animals are unable to synthesise carotenoids de novo, and so rely upon the diet as the source of these compounds. Carotenoids found in the human diet are primarily derived from crop plants, where the carotenoids are located in roots, leaves, shoots, seeds, fruit and flowers. To a lesser extent, carotenoids are also ingested from eggs, poultry and fish. Commercially, carotenoids are used as food colourants and in nutritional supplements (Table 13.1). Over recent years there has been considerable... 

Bixa Orellana seeds Bixin, norbixin (annatto) Food colouring... 

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. 

Castellar, M.R., Obon, J.M., and Eemandez-Lopez, J.A., The isolation and properties of a concentrated red-purple betacyanin food colourant from Opuntia stricta fruits, J. Sci. Food Agric., 86, 122, 2006. 

Sardaryan, E. et al., Arpink Red meet a new natural red food colourant of microbial origin, in Pigments in Pood More Than Colors, Dufosse, L., Ed., Universite de Bretagne Occidentale, Quimper, 2004, 207. 

Scotter, M.J., Castle, L., and Roberts, D., Method development and HPLC analysis of retail foods and beverages for copper chlorophyll (E 141 [i]) and chlorophyllin (E 141[ii]) food colouring materials, FoodAddit. Contam., 22, 1163, 2005. 

Ashkenazi, P., Yamitzky, C., and Casi, M., Determination of synthetic food colours by means of a novel sample preparations system. Anal. Chim. Acta, 248, 289, 1991. 

Cruces-Bianco, C., Garcia-Campana, A.M., and Ales-Barrero, F., Derivative spectrophotometric resolution of mixtures of the food colourants Tartrazine, Amaranth and Curcumin in a micellar medium, Talanta, 43, 1019, 1996. 

Masar, M., Kaniansky, D., and Madajova, V., Separation of synthetic food colourants by capillary zone electrophoresis in a hydrodynamically closed separation compartment, J. Chromatogr. A, 724, 327, 1996. 

Lau, O.W. et al., Spectrophotometric determination of single synthetic food colour in soft drinks using ion-pair formation and extraction, Int. J. Food Sci. TechnoL, 30, 6, 793, 1995. 

Joint FAOAVHO Expert Committee on Food Additives, Toxicological Evaluation of Some Food Colours, Enzymes, Flavour Enhancers, Thickening Agents, and Certain Other Food Additives, WHO Food Series, Geneva, 6, 74, 1975. 

EU Scientific Committee on Food, Opinion on Request for Use of Algal Beta-Carotene as a Food Colour, June 13, 1997. 

Dalzell, J.M., LFRA Ingredients Handbook, Food Colours, Leatherhead, 1997. Francis, F.J., Polyphenols as natural food colorants, in Polyphenolic Phenomena, Scalbert A., Ed., INRA, Paris, 1993, 209. 

Only food colouring should be used (redwood or onionskin have minimum sealing properties so eggs are poorly preserved). 

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

To be used successfully in bakery products a food colour needs the following attributes as well as complying with the appropriate legislation it should be stable to heat and light, stable to reducing sugars, and... 

There is as yet no agreed international list of permitted food colours. Thus a food dye that is permitted in one country may be considered unacceptable in another. The synthetic food colorants permitted in the European Union are listed in Table 1.8 [60]. All were originally introduced as acid dyes for wool many years ago. Furthermore, more than thirty colorants of natural origin are permitted in most countries. The natural carotenoid dyes are of outstanding importance for colouring edible fats and oils. These yellow to red methine dye structures occur in many families of plants and animals, including vegetables, berries,... 

Food colourant analysis characterisation of caramel colours and discrimination of malts from malt extracts. 

To select and determine the amount of food colours commonly found in test foods and to develop ELISA methods using 24 hr urinary samples to examine feasibility of urinary biomarkers. 

To develop a validated method for the determination of the food colour annatto in permitted foods with reference to the Colours in Food Additives Regulations 1995, as amended. 

The directive on colours for use in foodstuffs, 94/36/EC,4 replaced a previous positive hst of colours, but it goes much further to harmonise completely the laws of the EU member countries in respect of food colours, since, for many colours, the foods in which certain colours are permitted and maximum levels of use are prescribed. Colours are defined as substances which add or restore colour in a food, and include natural constituents of foodstuffs and natural sources which are normally not consumed as foodstuffs as such and not normally used as characteristic ingredients of food . 

Vitamins occur naturally in many foods and raw materials. However the natural contents are often supplemented in many food products to ensure an adequate intake, for example in infant formulae, breakfast cereals and clinical nutrition products. Vitamins are usually added as nutrients and thus not covered in this chapter but may also be added as food colours (riboflavin, carotenes). The reader should refer to the following references for recent developments in... 

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). 

Colours (decorative pigment, food colour, surface colourant)... 

Several amino compounds are being used extensively in industrial processes. Most of these compounds are manufactured, except hydrazine. Azo dyes are produced by diazotization of aromatic amines and currently there are at least 3000 azo dyes in use. These dyes are used widely in textiles, leather, printing, paper making, drug and food industries. In the past three decades many food, drug and cosmetic colours have been banned from commercial use as food colourants. This section gives a brief account of adverse affects caused by the use of various amino compounds. 

RP-HPLC has been applied for the determination of betalain pigments in various plants too. The researches were motivated by the commercial importance of betalain pigments as natural food colourants. An RP-HPLC method was developed for the measurement of betalain pigments in prickly pear (Opuntia ficus-indica) fruits. 

Fig. 3.32. Structures of eight synthetic food colourants. Reprinted with permission from Q. Chen et al. [111].

Another RP-HPLC technique has been applied for the determination of synthetic food dyes in soft drinks with a minimal clean-up. Separation of dyes was obtained in an ODS column (150 x 4 mm i.d. particle size 5 pm). Solvents A and B were methanol and 40 mM aqueous ammonium acetate (pH = 5), respectively. Gradient conditions were 0-3 min, 10 per cent A 3-5 min, to 25 per cent A 5-8 min, 25 per cent A 8-18 min, to 75 per cent A 18-20 min, 75 per cent A. The flow rate was 1 ml/min and dyes were detected at 414 nm. The separation of synthetic dyes achieved by the method is shown in Fig. 3.35. The concentrations of dyes found in commercial samples are compiled in Table 3.21. The quantification limit depended markedly on the type of dye, being the highest for E-104 (4.0 mg/1) and the lowest for E-102 and E-110 (1.0 mg/1). The detection limit ranged from 0.3 mg/1 (E-102 and E-110) to 1.0 mg/ml (E-104 and E-124). It was suggested that the method can be applied for the screening of food colourants in quality control laboratories [113]. 

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