Food adulteration is the deliberate attempt to debase the quality of edible material. Food adulteration has been taking place for centuries. In the nineteenth century, instances such as sand in bread and plaster of Paris in cheese led to the first UK law against adulteration in 1860. In modern society, food adulteration is much more likely to be chemical-based, with additives and preservatives. There are several experiments a class can carry out to explore the chemical manipulation of food.
Chalk or washing powder in sugar
Chalk and washing powder are common adulterants used to increase the quantity of sugar. To test for their presence, place a small amount of sugar in a test tube and add a few drops of hydrochloric acid to the sugar. If the mixture effervesces (bubbles indicating the release of carbon dioxide) one of these adulterous substances is present.
Menatil yellow in turmeric
Menatil yellow is a form of dye sometimes used to add colour to turmeric. It has been outlawed in India after long-term consumption was discovered to affect cognitive development in rats. Test for menatil yellow by placing a small amount of turmeric in a test tube and add a few drops of hydrochloric acid. If the space takes on a pinkish colour, menatil yellow is present.
Dyes in fat
Many edible fats, such as lard and butter, can be adulterated with dye to give them a particular colour. To test for dyes place, 1ml of fat in a test tube with 1ml of sulphuric acid and 4ml of acetic acid. Heat gently over a Bunsen burner. If the fat turns a pink or red colour, dye is present.
Argemone in oil
Argemone oil is derived from sunflowers, but consumption can cause health disorders, especially in children. It is sometimes used to adulterate other edible oils, such as olive oil and rapeseed oil. Place a small amount of the edible oil in a test tube and add a few drops of nitric acid. Shake the test tube. If the oil turns a reddish-brown colour, argemone oil is present.
Malachite in green peas
Malachite green is a chloride compound sometimes used to give beans a more vibrant green colour, and it can prove carcinogenic to humans if consumed over a long period of time. Rub a green bean with moistened blotting paper. If traces of green colour adhere to the paper, malachite green is present.