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| Food Adulteration |
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| The deliberate contamination of food materials with low quality, cheap, non-edible or toxic substances is called food adulteration. The substance which degrades (lowers) the quality of a food is called an adulterant. |
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| Adulteration results in two disadvantages for the consumer. |
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| 1. Overpaying for substandard food stuff. |
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| 2. Some adulterants are injurious to health and can even result in death. (Adulteration of mustard oil with Argemone oil causes dropsy which is fatal.) |
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| Table 10. Common adulterants in food. |
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| Test for Detecting Adulteration in food. |
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| a) Vanaspati (hydrogenated vegetable fat) in ghee or butter |
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| Vanaspati being much cheaper than ghee is often used to adulterate ghee or butter. Melt a teaspoonful of ghee or butter sample in a test tube. Add an equal quantity of concentrated hydrochloric acid and a pinch of sugar. Shake the test-tube well and allow it to stand for a few minutes. Appearance of a deep red colour in the lower layer shows the presence of vanaspati in ghee or butter. |
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| b) Water in milk |
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| Mixing water with milk is a common practice amongst milk vendors. Take a drop of milk on a glass plate and hold it vertically. If the drop of milk sticks to the glass plate or flows down slowly, leaving behind a white trail, then the milk sample is pure. If the milk drop runs down quickly on the glass plate, leaving behind no white trail, then the milk has been diluted with water. This is because when pure milk is adulterated by mixing with water, then its viscosity decreases i.e. it becomes very thin. For testing the quantity of water in skimmed milk, an instrument called the lactometer should be used. If the milk is unadulterated the lactometer reading should be 1.026. |
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| c) Argemone oil in Edible oil |
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| Argemone oil is a highly toxic oil which when consumed by man can cause a disease called dropsy. To test the presence of this oil in cooking oil, take the sample to be tested in a test tube and add some concentrated nitric acid to it. Shake the test tube well and observe the colour of the acid layer (which is the lower layer). Presence of argemone oil in the sample is confirmed with the appearance of a reddish colour in the lower layer. |
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| d) Metanil Yellow in Dal |
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| Metanil yellow is a dye having toxic effects. To test the presence of metanil yellow in dal, take about 5 gms of dal in a test tube and then add 5 ml of water. Shake the test tube well. Then add a few drops of concentrated hydrochloric acid to the test tube. The presence of metanil yellow in dal is confirmed with the appearance of a pink colour in the solution. |
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