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Identification of synthetic food colours adulteration
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Thursday, 25 June, 2020, 08 : 00 AM [IST]
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Singupurapu Bhargavi
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Synthetic food colours are chemicals that originate from coal tar derivatives, and most of them contain an azo group. Synthetic food colours, also known as artificial food colours, are processed & manufactured chemically. These colours are usually water-soluble and can be used in foods without any further processing.
Synthetic food colours are widely used in different types of food stuffs such as bakery products, confectioneries, jellies, and beverages available in the market of India as well as in the world because they are less expensive but they are also effective in giving an intense and uniform colour.
Changing lifestyles across the globe have transformed food habit patterns. Some of the common food colours are tartrazine, sunset yellow, amaranth, allure red, quinoline yellow, brilliant blue, and indigo carmine. Many methods have been used for the identification of the different colours used in food processing but traditionally chromatographic methods and spectrophotometric methods are used.
Synthetic food colour adulteration – Why to identify?
Colour is a key constituent of food and beverages. Synthetic food colours aid to mask defects in food making and substandard foods look superior. Consumers demand colour and variety in foods so as the traders make their goods look superior, attractive and thereby increase sales and profit. The use of nonpermitted colours and indiscriminate use of permitted colours are known to cause adverse health effects in experimental animals and in humans. Synthetic food colours react with food and change into poisons in the body, causing mutations, cancer and other toxic effects that produce allergic reactions in several individuals and also problems in children including allergies, hyperactivity, learning impairment, irritability and aggressiveness.
Colour extraction method
The sample solution is prepared by taking measured 2g of sample is dissolved in 10ml of distilled water in a test tube. Then placed in the centrifuge at 50,000 rpm. After 10-15 min samples are taken out and filtered. Then the filtrate 0.5ml is collected in the test tube and makeup to 3ml by adding distilled water.
Paper chromatography method and spectrophotometric method
Paper chromatography plays the most important role as it was found that the results are reliable, obtained by paper chromatography. Paper is a type of partition chromatography in which compounds are distributed between 2 liquids (Stationary phase and Mobile phase). The stationary phase is the fibre of the paper. The mobile phase is a liquid or developing solvent. Whatman filter paper is used for paper chromatography. In paper chromatography, by using solvent {sodium acetate (3 g): ammonia (10 ml): distilled water (100 ml)}, samples and standards are compared with the Reference value.
Based on the Reference value of standard and samples, these synthetic food colours are separated and identified. UV Visible Spectroscopy is also another most important method for the identification of synthetic food colours because all colourants have been characterised by this method. It is mainly based on the beer’s law and lamberts law. In the UV-Visible spectrophotometer, the absorption of synthetic food colours in both standards and samples are compared. The absorbance of standards and samples are graphically represented at particular wavelength points.
It is concluded that paper chromatography is a preliminary examination for synthetic food colours and UV-V is spectrophotometer is widely used for qualitative analysis. These methods are mainly to detect the presence of synthetic food colours adulteration in food colours are separated and identified based on the Rf value and identified the Rf value of the synthetic food colours of standards and samples.
Synthetic food colours have been increasingly used than natural food colours by food manufacturers to attain certain properties such as low cost, improved appearance, high colour intensity, more colour stability, and uniformity. There is a great need to create awareness at different levels about the toxic effects of synthetic food colours.
Adulterations may lead to food poisoning. Synthetic food colour adulterations are more vulnerable even to lesser toxicity and food poisoning and sometimes death may also occur especially in children. Nowadays, synthetic food colours are frequently used, therefore, the implementation of regulations and awareness programmes of food colours for consumers and food manufacturers is highly recommended.
(The author is M Tech scholar, Department of Food Technology, Faculty of Engineering and Technology, JAIN [Deemed-to-be University], Bengaluru. She can be contacted at bhargavipavani272@gmail.com)
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