Color in foods

Finale Color in Foods, Photochemistry, Photoluminescence, Pharmaceuticals, Fireworks, Fun, and the Future 

This final chapter will alliteratively pick up many topics that fell outside the trajectory traced by the history-chemistry—color interface in the previous seven chapters. We will see how colored additives affected the food quality of the past and, by extension, how color has affected, and continues to influence, so many other aspects of our daily lives. 

In 1820 and later in the 1850s in Britain, Accum (1769-1838) and Hassall (1817-1894), respectively, blew the whistle on the practice of food adulteration, much to the chagrin of the food purveyors of the day. Much of the practice had the goal of adding bulk and weight to the food, such as bread, with less expensive, and often non-nutritious or harmful, additives. But one goal for many producers was to make the food attractive—a practice carried out today in a much more sophisticated manner. 

Coloring food and drink in order to deceive is certainly not a new practice. Pliny the Elder in the third century BCE comments on the wine industry in Roman Gaul [1]  

Combatting such practices was a long time in coming. The first recorded pure food laws were enacted in thirteenth century Europe [2], but enforcement always lagged behind the actual law, and things really got out of hand with the great trade expansion of the sixteenth and seventeenth centuries when all kinds of exotic and expensive brews and spices were imported into Europe. 

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H. Lieber, The Use of Coal-Tar Colors in Food Products, H. Lieber Co., New York, 1904. Interesting historically. 

Psychophysical Methods for Measurement and Designation of Reflectance Color in Foods... 

Carmine (or cochineal) is used as a colorant in food, cosmetics, and paints. 

The same properties hold for colorants in food interference colors, illumination conditions, and fluorescence partially determine the appearance of food. 

In the preceding section, we presented principles of spectroscopy over the entire electromagnetic spectrum. The most important spectroscopic methods are those in the visible spectral region where food colorants can be perceived by the human eye. Human perception and the physical analysis of food colorants operate differently. The human perception with which we shall deal in Section 1.5 is difficult to normalize. However, the intention to standardize human color perception based on the abilities of most individuals led to a variety of protocols that regulate in detail how, with physical methods, human color perception can be simulated. In any case, a sophisticated instrumental set up is required. We present certain details related to optical spectroscopy here. For practical purposes, one must discriminate between measurements in the absorbance mode and those in the reflection mode. The latter mode is more important for direct measurement of colorants in food samples. To characterize pure or extracted food colorants the absorption mode should be used. 

Nielsen, S.R. and Holst, S., Developments in natural colourings, in Color in Food Improving Quality, MacDougall, D., Ed., Woodhead Publishing, Cambridge, U.K., 2002. 

Calvo C. and Salvador A., Use of natural colorants in food gels inflnence of composition of gels on their colour and study of their stability during storage. Food... 

The phycobiliproteins are accessory photosynthetic pigments aggregated in cells as phycobilisomes that are attached to the thylakoid membrane of the chloroplast. The red phycobiliproteins (phycoerythrin) and the blue phycobiliprotein (phycocy-anin) are soluble in water and can serve as natural colorants in foods, cosmetics, and pharmaceuticals. Chemically, the phycobiliproteins are built from chro-mophores — bilins — that are open-chain tetrapyrroles covalently linked via thio-ether bonds to an apoprotein. ... 

Gonzalez, M., Gallego, M., and Valcarcel, M., Automatic screening method for the rapid and simple discrimination between synthetic and natural colorants in foods. Anal. Chim. Acta, 464, 237, 2002. 

The official permission to use a synthetic colorant in food is determined by its quality and safety. Detailed and accurate analysis became compulsory in order to verify purity and quantify the labeled concentrations of colorants in food. For the analysis of synthetic colorants added to food products, (1) simple and rapid methods are used to determine their presence, (2) accurate and precise methods evaluate then-concentrations, or (3) certain methods evaluate their degradations to unstable and unsafe forms. This chapter is dedicated to these three methods used to identify and quantify synthetic colorants as pure or mixed pigments in foodstuffs. 

Solid phase spectrophotometry proved to be an appropriate technique for the determination of colorants in foods dne to its simplicity, selectivity, reasonable cost, low detection limits, and use of conventional instrnmentation. This simple, sensitive, and inexpensive method allowed simnltaneons determinations of Snnset Yellow FCF (SY), Quinoline Yellow, and their nnsnlfonated derivatives [Sndan I (SUD) and Quinoline Yellow Spirit Soluble (QYSS)] in mixtnres. Mixtnres of food colorants containing Tartrazine, Sunset Yellow, Ponceau 4R, Amaranth, and Brilliant Blue were simultaneously analyzed with Vis spectrophotometry without previous chemical separation. ... 

Francis, F.J., Pigments and other colorants, in Food Chemistry, 2nd ed., Fennema, O.R., Ed., Marcel Dekker, New York, 1985. 

Finally, passing mention must be made of the two most important organic pigments in our world, both natural products. These are chlorophyll and haemoglobin, which are absolutely vital in the strict meaning of the word, but only chlorophyll has found a commercial use as a colorant in food preparation. 

Copies of regulations governing the listing, certification, and use of colors in foods, drags, devices, and cosmetics shipped in interstate commerce or offered for entry into the United States, or answers to questions concerning them, are available from the Food and Drag Administration. Recommendations on submission of chemical and technological data are provided in the FDA s online publication (http //vm.cfsan.fda.gov/ -dms/opa-coll.html). 

The appreciation of color and the use of colorants dates back to antiquity. The art of making colored candy is shown in paintings in Egyptian tombs as far back as 1500 bc. Pliny the Elder described the use of artificial colorants in wine in 1500 bc. Spices and condiments were colored at least 500 years ago. The use of colorants in cosmetics is better documented than colorants in foods. Archaeologists have pointed out that Egyptian women used green copper ores as eye shadow as early as 5000 bc. Henna was used to redden hair and feet, carmine to redden lips, faces were colored yellow with saffron and kohl, an arsenic compound, was used to darken eyebrows. More recently, in Britain, in the twelfth century, sugar was colored red with kermes and madder and purple with Tyrian purple. 

By early 1910, the bulk of Hesse s work had been completed. In June, he finally returned to the original work he had abandoned in 1907, the devising of a scheme for the detection, separation, and identification of coal-tar colors in foods. This work was also necessary as the government could not successfully prosecute a manufacturer for using a poisonous color in his products unless the dye s presence could be demonstrated. Over the next several months he completed this work with the assistance of a Bureau staff chemist. No report of this work was ever published (62). 

Carotenoids produced in plants are used as colorants in foods and aiflmal feeds and can also have an antioxidant function. Production of phytoene synthase is the first committed step towards carotenoid biosynthesis in plants. When phytoene synthase is produced in B. napus, a 50-fold increase in carotenoid expression results. Therefore Brassica... 

Color in food products ranks second in importance to taste in relation to consumer acceptability of a product. Discoloration problems caused by plant-protein products must be solved if these products are to be accepted. Isolation and identification of the pigments producing color is an important step in solving this problem and the methods developed in the studies presented in this chapter with cottonseed flours are applicable to color problems caused by other plant-protein products. 

The purpose of this section is to provide a review of HPLC methods available for the determination of synthetic colors in foods, including sample preparation, separation techniques, and detection systems. 

NP Boley, NG Bunton, NT Crosby, AE Johnson, P Roper, L Somers. Determination of synthetic colors in foods using high performance liquid chromatography. Analyst 105 589-599, 1980. 

C Graichen. Quantitative determination of FD C colors in foods. J Assoc Off Anal Chem 58(2) 278-282, 1975. 

The synthetic color industry dates back to the accidental discovery of the first synthetic organic dye (mauve) in 1856. Sir William Henry Perkin, in an unsuccessful attempt to synthesize quinine, succeeded in obtaining a violet dye by the oxidation of aniline. This led other scientists to experiment and discover many new colors with superior properties to the natural pigments and extracts. The use of these new and different colors in foods, drugs, and cosmetics began almost immediately because of their tinctorial value, stability, and the many shades in which they were available. 

Pood colors. In Food and Nutrition Board, National Academy of Sciences Washington, DC, 1971. 

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