Chemical Test for Various Adulteration in Food
by lechu on January 28, 2010
In an exhibition, fair or at an organized public awareness show, the demonstration of the detection of adulteration of food will be much effective and attractive, if the samples of adulterated food materials and their adulterants are displayed side by side. It will be more communicative and exert greater impact on the audience, if audio-visual system displays the adverse and injurious effects of different adulterants in growth and maintenance of good health are projected. Such visuals may also be designed locally.
Following are the chemical test to find out various adulterants present in our food
- ASAFOETIDA: Resin and Colour (adulterant)
Chemical test: Take a small quantity of the asafetida in test tube. Add 3 ml of distilled water and shake the tube gently. Pure Asafetida dissolves in the water soon, and produces a milky white colour. But in case of adulteration by the chemical colour, the mixture turns to be colored. The purity of Asafetida also can be tested by taking a small quantity of it, on the tip of forceps and placing the same on the flame of a spirit lamp. Asafetida produces bright flame burning quickly, leaving the impurities behind. - COFFEE POWDER: Cereal Starch (adulterant)
Chemical test: Take 1/4th of a teaspoon of coffee powder in a test tube and add 3 ml of distilled water in it. Light a spirit lamp and heat the contents to colorize. Add about 33 ml of Potassium Permanganate Solution and Muriatic Acid (1:1) to decolorize the mixture. The formation of blue colour in the mixture, when adding a drop of 1% aqueous solution of Iodine indicates adulteration with starch - COFFEE POWDER: Scorched Persimmon stones (adulterant)
Chemical test: Take 1 teaspoon of the coffee powder and spread it on a moisturized blotting paper. Pour 3 ml of 2% Aqueous Solution of Sodium Carbonate slowly and carefully on it. A red coloration indicates the presence of the powder of Scorched Persimmon Stones in the Coffee Powder. - DRY RED CHILLI: Rhodamine B colour (adulterant)
Chemical test: Take a red chilly for the dry red chilly, and rub the outer surface with a piece of cotton soaked in Liquid Paraffin. If the cotton becomes red, the sample is adulterated. - TURMERIC POWDER: Metanil Yellow colour
Chemical test: Take a cotton piece soaked in Liquid Paraffin, and rub the dry piece of turmeric root. If the cotton becomes yellow, we can say that the turmeric root has been adulterated with Metanil Yellow colour. - EDIBLE OIL: Prohibited colour
Chemical test: Take 20 drops of the edible oil in each of 4 test tubes. Make 3 different solutions, mixing up 1 part of distilled water, 3 parts of distilled water and 4 parts of distilled water. Add 2 ml of each solution in each of e test tubes and add 2 ml of hydrochloric acid in the 4th test tube. Shake up each tube to mix up the contents thoroughly. A rosy colouration in the mixture of any tube, indicates the presence of prohibited colour in the edible oil. - EDIBLE OIL: Cyanide
Chemical test:Take 3 ml of the edible oil in a test tube. Add 10 drops of alcoholic potash, and heat the tube on the flame of a spirit lamp. Make an addition of a little amount of each of ferrous sulphate and ferric chloride in the test tube, and shake it to mix up the contents thoroughly. Add 3 ml hydrochloric acid. The blue colouration indicates the presence of hydrocyanic acid, which get produced due to presence of cyanide in edible oil. - EDIBLE OIL: Lube oil
Chemical test: Take 20 drops of edible oil in a test tube. Add 10 drops of alcoholic potash. Heat the tube on the flame of a spirit lamp. The mixture will de-colourise. Now add 10 drops of dichloroquinol chloride. Again heat the tube. The appearance of the blue colour indicates the presence of a compound of triorthocrysyle phosphate (TOCP), which leads to incidence of paralysis. Traces of this compound in edible oil, point to an admixture of edible oil, with lube oil. - EDIBLE OIL: Rancidity
Chemical test: Take 3 ml of the edible oil in a test tube. Add 3 ml of hydrochloric acid, in it. Close the mouth of the test tube. Mix up the contents thoroughly by shaking. Add 3 ml of 0.1% phloroglucinol solution in it. Shake the test tube vigorously for 2 minutes and keep it aside. Examine the test tube after 30 minutes. A pink or red colouration in acid layer indicates that, the oil sample is rancid. - GHEE: Dalda
Chemical test: Take 3 ml of ghee in a test tube. Add 10 drops of hydrochloric acid or muratic acid, and 1/4th of teaspoon of sugar. Shake the tube to mix up the contents thoroughly. Examine the test tube after 5 minutes. The red colouration will indicate the presence of dalda in the ghee. - GRAM POWDER: Khesari Powder
Chemical test: Take ½ teaspoon of the gram powder in a test tube and add 3 ml of distilled water in it. Then pour 3 ml of Muratic Acid in the test tube. Immense the test tube in water. Check the test tube after 15 minutes. A violet colouration indicates that Khesari Powder is present in the Gram Powder. - GRAM POWDER: Metanil Yellow Colour
Chemical test: Take ½ teaspoon of the gram powder in a test tube. Pour 3 ml of alcohol in the test tube. Mix up the contents thoroughly by shaking the test tube. Add 10 drops of Hydrochloric Acid in it. A pink colouration indicated presence of Metanil Yellow in the Gram Powder. - GREEN VEGETABLE LIKE GREEN CHILLI etc: Malachite Green colour
Chemical test: Take a cotton piece soaked in Liquid Paraffin, and rub the outer green surface of a small part of the green vegetable. If the cotton turns Green, we can say that the vegetable is adulterated with Malachite Green colour. - JAGGERY: Sodium Bicarbonate
Chemical test: Take 1/4th of a teaspoon of the jaggery in a test tube. Add 3 ml of Muratic Acid. The presence of Sodium Carbonate effects effervescence. - JAGGERY: Metanil Yellow Colour
Chemical test: Take 1/4th of a teaspoon of the jaggery in a test tube. Add 3 ml of alcohol and shake the tube vigorously to mix up the contents. Pour 10 drops of Hydrochloric Acid in it. A pink colouration indicates the presence of Metanil Yellow Colour in Jaggery. - LEMONADE SODA: Mineral Acid
Chemical test: Pour 2 drops of the lemonade soda on a Metanil yellow paper-strip. A violet colouration indicates the presence of mineral acid in aerated water. The colour impression gets retained even after drying the paper (you can prepare Metanil yellow paper-strips by soaking filter paper-strips in 0.1% aqueous solution, and then drying the paper-strips).. - MILK: Sodium Bicarbonate
Chemical test: Take 3 ml of the milk in a test tube. Add 10 drops of rosalic acid solution. The rosy colouration indicates the presence of sodium bicarbonate in the milk. - MILK: Glucose
Take a teaspoonful of the milk in a test tube. Dip a strip of diastix in it for 30 seconds. A change in colouration from blue to green, indicates the presence of glucose in the milk. - MILK: Sugar
Chemical test: Take 3 ml of the milk in a test tube. Add 2 ml of hydrochloric acid or Muratic acid in it. Heat the test tube after adding 50 mg of resorcinol. The red colouration indicates the use of sugar in the milk. The detection may also be made by a different test. Take a teaspoonful of milk in a test tube. Add 1 mg of invertase enzyme. After 5 minutes, dip a strip of diastix in it. Take out the strip after 30 seconds. A change in colour from blue to green, indicates the use of sugar in the milk. - MILK: Cereal Starch
Chemical test: Take 3 ml of the milk in a test tube. Add 1 drop of 1% aqueous solution of iodine. The blue of deep blue colouration indicates the presence of cereal starch in the milk. - MILK: Urea
Chemical test: Take a teaspoonful of milk in a test tube. Add a ½ teaspoon of soyabean or arhar-powder. Mix up the contents thoroughly by shaking the test tube. After 5 minutes, dip a red litmus paper init. Remove the paper after half a minute. A change in colour from red to blue, indicates the presence of urea in the milk. - MILK: Boric Acid
Chemical test: Take 3 ml of milk in a test tube. Add 20 drops of hydrochloric acid and shake the test tube to mix up the contents thoroughly. Dip a yellow paper-strip, and remove the same after 1 minute. A change in the colour from the yellow to red, followed by the change from the red to green, by addition of ammonia-drop solution, indicates that the boric acid is present in the milk (to prepare the yellow paper-strips, dip strips of filter paper in an aqueous solution of the turmeric, and dry it up). - MILK: Dalda
Chemical test: Take 3 ml of milk in a test tube. Add 10 drops of hydrochloric acid or Muratic acid. Mix up one teaspoonful of sugar. After 5 minutes, examine the mixture. The red coloration indicates the presence of dalda in the milk. - MUSTARD OIL: Argemone Oil
Chemical test: Take about 3 ml of the mustard oil in a test tube. Add 20 drops of nitric acid. For 3 minutes, heat the tube on the flame of a spirit lamp. A red colouration indicates the presence of Argemone oil in the mustard oil. - MUSTARD OIL: Cotton Seed Oil
Chemical test: Take about 3 ml of the mustard oil in a test tube. Add 2 ml of amyl alcohol in it and 1 ml of carbon disulphide and a little amount of sulpher. Plug the mouth of the test tube and heat it on the flame of a spirit lamp for 3 minutes. A red colouration indicates the presence of cotton seed oil in the mustard oil. - MUSTARD OIL: Mineral Oil
Chemical test: Take about 3 ml of the mustard oil in a test tube. Add 20 drops of alcoholic potash. For 3 minutes, heat the test tube on the flame of a spirit lamp, to effect de-colourisation of the mixture. Shake the test tube after adding 10 drops of distilled water. Examine the Test tube to trace the turbidity. Continue the activity of adding water upto 15 ml, and the examination of the test tube for appearance of turbidity. The turbidity appearance indicates the presence of mineral oil in the mustard oil. - MUSTARD OIL: Castor Oil
Chemical test: Take about 3 ml of the mustard oil in a test tube. Add 2 ml of petroleum ether. Shake the test tube and mix up the contents thoroughly. Keep the tube immersed in the salt-ice mixture, or in a pot of cold saline water. Examine the test tube after 5 minutes. The appearance of turbidity in the mixture indicates the presence of castor oil in the mustard oil. Similar test may also be made to detect adulteration of mustard oil with coconut oil, or dalda (vanaspati). - PARCHED RICE: Urea
Chemical test: Take 30 numbers of Parched Rice in a test tube. Add 5 ml of distilled water in it. Mix up the contents thoroughly, by shaking the test tube. After 5 minutes, filter the water-contents, and add ½ teaspoon of powder of Arhar or Soyabean in it. Leave it for 5 minutes, and then dip a red Litmus Paper in the mixture. Take out the Litmus Paper after 30 second and examine it. A blue colouration indicates the presence of Urea in the Parched Rice. - PROCESSED FOOD, SWEET or SYRUP: Rhodamine B colour
Chemical test: If this chemical colour is present in the food, it is very easy to detect. Because it shines very brightly under the sun. Also it can be detected by a more precise method. Take ½ teaspoon of the sample in a test tube. Pour 3 ml of Carbon Tetrachloride and shake the test tube to mix up the contents thoroughly. The mixture turns colourless and addition of a drop of Hydrochloric Acid brings the colour back, when food contains Rhodamine B colour. - RABRI (a sweet prepared by condensing the films of milk): Blotting Paper
Chemical test: Take 1 teaspoonful of rabri in a test tube. Add 3 ml of hydrochloric acid or muratic acid and 3 ml of distilled water. Stir the contents with a glass rod. Remove the rod and examine. Presence of finer fibres to the glass rod, will indicate the presence of blotting paper in rabri. - RED CHILLI POWDER: Rhodamine B colour
Chemical test: Take 1/4th teaspoon of the red chilli powder in a test tube. Add 3 ml of distilled water in it, and 10 drops of carbon tetrachloride. Vigorously shake the tube to mix up the contents. The red colour will disappear as the result of the shake, and if the red colour reappears with the addition of a drop of hydrochloric acid, the adulteration of Rhodamine B colour in the chilli powder is positive. - SWEET CARD: Dalda
Chemical test: Take 1 teaspoonful of sweet card in the test tube. Add 10 drops of hydrochloric acid or muratic acid. Mix up the contents shaking the test tube gently. After 5 minutes, examine the mixture. The red colouration indicates the use dalda in the sweet card. - SWEET POTATO: Rhodamine B colour
Chemical test: Take a cotton piece soaked in Liquid Paraffin, and rub the outer red surface of the sweet potato. If the cotton absorbs colour, it indicates the use of Rhodamine B colour on outer surface of the sweet potato. - TURMERIC POWDER: Metanil Yellow colour
Chemical test: Take 1/4th of teaspoon of Turmeric Powder in a test tube. Add 3 ml of alcohol in it. Shake the tube thoroughly to mix up the contents. Add 10 drops of Muratic Acid or Hydrochloric Acid in the test tube. A pink colouration indicates the presence of Metanil Yellow colour in the Turmeric Powder.