Study of common food adulterants in fats, oils, butter, sugar, turmeric powder, chili powder and pepper

Adulteration is one of the most serious problems faced by consumer today. The adulterated food produces serious effects such as cancer, stomach ulcers, diarrhea, respiratory diseases like asthma, allergy etc. the adulterants used by manufacturers and retailers are cheap substituent. For example, fats, oils and butter are adulterated with paraffin wax, vanaspati ghee, Castrol oil, powdered sweet potatoes or some starchy material. Red chili powder is mixed with brick powder, sugar with chalk powder and pepper is mixed with dried papaya seeds. All these adulterants can be easily identified by simple chemical tests.

AIM OF PROJECT:

This project deals with the study of detection of common food

adulterants present in different

food-stuff.

THEORY:

Fats, oils and butter are usually adulterated with paraffin wax, vanaspati ghee, hydrocarbons, powdered sweet potatoes, dyes and argemone oil. These are detected as follows:

Requirements:

Test tubes, test tube stand, conc. HCl, conc. H₂SO₄, 2% alcoholic solution of furfural, acetic acid, iodine solution, conc. HNO₃, sample of fat, butter and oil.

Procedure:

(i) Detection of vanaspati ghee in desi ghee: take about 1 g of given sample of desi ghee or butter in a test tube. Add 1 ml of dill HCl and 1-2 drops of 2% alcoholic solution of furfural. Shake the mixture thoroughly

EXPERIMENT 10.1

To detect the presence of adulterants in oil, fats and butter.

a pink or red color in the acid layer indicates adulteration of desi ghee by vanaspati ghee.

(ii) Detection of paraffin wax or hydrocarbon in vegetable ghee: heat small amount of vegetable ghee with acetic anhydride. A droplet of oil floating on the surface of unused acetic anhydride indicates the presence of wax or hydrocarbons.

(iii) Detection of dyes in fat: heat 1 ml of fat with a mixture of 1 ml of conc. H₂SO₄ and 4 ml of acetic acid, appearance of pink or red color indicates presence of dyes in fats.

(iv) Detection of starchy material: take about 0.5 g of desi ghee or butter in a test tube, add 2 ml of water and boil. Cool and add about 1-2 drops of iodine solution, a blue color indicate starch in given sample of desi ghee or butter.

(v) Detection of argemone oil in edible oil: to small amount of oil in a test tube, add a few drops if conc. HNO₃ and shake. Appearance of red color in acid layer indicates presence of argemone oil.

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THEORY:

Turmeric powder is adulterated with yellow colored chalk or lead chromate. Lead is extremely harmful for health if consumed. The presence of chalk may be detected by brisk evolution of carbon dioxide on treatment with dill. HCl. Presence of lead salt may be detected by the appearance of yellow ppt. when the solution of the sample in HNO₃ is treated with pot. Iodine solution.

Red chili powder is usually adulterated with red colored brick powder. On dissolving in water, brick powder settles down because it is heavier than the chili powder.

Black pepper is usually mixed with papaya seeds because they have the same color and size, but papaya seeds are much lighter than pepper seeds. On adding water, papaya seeds float on the surface of water and pepper settles down.

Requirements:

Dil. HNO₃, conc. HCl, KI solution, test tubes, beakers, sample of turmeric, chili powder and pepper.

Procedure:

EXPERIMENT 10.2

(i) Detection of yellow chalk and yellow lead salts in turmeric powder:

(a) Take about 1 g of the given sample in a test tube and add about 1 ml of dil. HCl. Evolution of CO₂ gas with effervescence indicates presence of yellow chalk in turmeric powder.

(b) Take about 0.5 g of the given sample in a test tube and add 2.0 ml of dil. HNO₃. Shake and filter. Add a few drops of kI solution to the filtrate a yellow ppt. of PbI₂ indicate adulteration of lead salt in the given sample of turmeric.

(ii) Detection of brick powder in chili powder: take about 2 g of chili powder in a 100 ml conical flask and add about 50 ml of water. Shake and allow standing. Setting of any heavier red colored particles at the bottom of the flask indicates adulteration by brick powder.

(iii) Detection of dried papaya seeds in water: Take about 50 ml of water in a beaker and add about 5 g of given sample of pepper. Stir with a glass rod and allow standing. Any light floating on the surface indicates he adulteration by papaya seeds in pepper.

(iv) Detection of red lead salt in chili powder: To a sample of chili powder, add dil. HNO₃. Filter the solution and add 2 drops of potassium iodide solution to the filtrate. Yellow ppt. indicates the presence of lead salt in chili powder.

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THEORY:

Sugar is adulterated with chalk or washing soda or some water insoluble materials. Since sugar is soluble in water, any insoluble material can be detected by dissolving the given sample of sugar in water. Presence of washing soda or chalk can be detected by treatment with dil. HCl and evolution of carbon dioxide.

Requirements:

Sample of sugar, dil. HCl, beaker and test tube.

Procedure:

(i) Detection of insoluble materials in sugar: Take a small amount of sugar in test tube and dissolve in water. Presence of any insoluble material indicates adulteration.

(i) Detection of chalk powder and washing soda: Take a pinch of sugar and add 2-3 drops of HCl. Brisk effervescence of CO₂ gas shows presence of chalk powder of washing soda in given sample of sugar.

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EXPERIMENT 10.2